Questions on: Hydrangea

Ron Smith, Horticulturist, NDSU Extension Service


Q: We just moved to the outskirts of Omaha, Neb. We planted about 60 bushes, a garden and 15 fruit trees. It probably was not a smart idea doing so much planting the first year, but everything is growing well. The hydrangeas flowered for a few days, but then all the flowers and leaves dropped off. Then they sprouted new leaves and flowers for a day or two, but now those have died. The plants look like they're ready for winter, but it's only June. Have we lost them or is there a chance they may come back? What would be the ideal place to plant hydrangeas? Right now they get about five to six hours of sun. We have clay soil, but did put them in a big hole with better soil around it. What about the amount of water they like? We also have other problems. Our burning bushes look OK, but a lot of the leaves have fallen off. The rose bushes look great, but the flowers we've had seem to open, look wilted and die in a 24-hour period. Are they getting too much water? (e-mail reference)

A: I am at a loss as to why your hydrangeas are not performing up to par! Generally, these are one of the easiest flowering shrubs to grow and reward the owner by having big, beautiful blooms. During the first year, keep the soil moist to prevent wilting. Once established, hydrangeas are almost indestructible! Check the stems to see if the cambial tissue is still green beneath the bark. Scrape it with a pocket knife or your thumbnail. If green, there's a good chance they will come back. As far as the site goes, it sounds about right. The burning bush probably is going through transplant/new environment shock, but should recover. The roses may be getting hit by a fungal disease, such as Botrytis, because your description closely matches the symptoms. Correct the problem by not doing overhead watering and pruning out excessive branches to improve air circulation. Do not overfertilize. If the roses are surrounded by ground cover, remove it. Pick up and dispose of all fallen leaves and spent flower buds to prevent reinfection.


Q: I have a shooting star hydrangea that is in the process of budding. I just noticed fresh sawdust on the leaves and found a hole in one of the canes. Is there anything I can do to stop and/or prevent this from happening? (southern Delaware)

A: This is a cane borer. Cut the affected area well back from where you see the activity taking place and spray on an insecticide sold on the market as "Bayer's Advanced Tree and Shrub Insecticide." Be sure to follow the label directions.


Q: I have a hydrangea snowball shrub. I am wondering how to start another one. I've heard that if it is a flowering plant, it will not root. Is this true or do I need to start from a rooted piece? (e-mail reference)

A: Hydrangeas are among the easier plants to root. Take a cutting from a branch of the hydrangea shrub about 5 to 6 inches long. The cutting will work best if taken from a branch that did not flower this year. Remove the lower leaves of the bottom two leaf nodes. Cut the largest leaves down to about half their size. Dip the cuttings in rooting hormone (this is entirely optional) and insert into a damp vermiculite or sterile medium. Water the pot well and allow draining. Make sure the soil is moist, but not soggy. Cover the cuttings and pot with plastic. Try to keep the plastic from touching the leaves by adding stakes.


Q: I have four, beautiful, endless summer hydrangea bushes in front of my house. They're new plants and are full of blooms. I'd like to cut some blooms for fresh flowers in my home, but I don't want to damage the plant. Is it OK to cut stems off for a bouquet? How far down should I cut them? Also, I've heard that the endless summer variety will bloom all summer, so I am curious how to best facilitate this continuous blooming. Will cutting blossoms help? Thanks for your advice! (Omaha, Neb.)

A: Yes to both of your questions. Keep the plant hydrated with regular watering, but don't keep the soil soggy. Fertilizing the plant once a month with something, such as Miracle-Gro, also will help. You can cut back far enough to make a nice bouquet as long as you leave some foliage behind on the stem.


Q: I am moving to a little house in Hudson, Wis. There's what I'd call a stand of hydrangea on the north side of the house. This clump is withered, brown and tangled. It does show signs of having bloomed last year. Should I prune or feed the plants? Should I cut the clump to the ground and wait? I've no idea what color they might be or what varieties of hydrangea they are. I'd love to look out the kitchen window and see them thriving and blooming. Any general hydrangea advice you have would be most welcome. (e-mail reference)

A: There are many cultivars and species of hydrangea in the northern part of the country. Some bloom on last year's wood. Others bloom on the current season's growth and some do both. I would suggest cutting them back to about knee high and see what happens this spring. If you don't get flowers, then you know you should leave them alone to get flowers next year. Most hydrangeas respond well to a good pruning early in the spring.


Q: A lady just called to find out how to care for her white hydrangeas during the winter. Would she take care of it the same as her endless summer hydrangea? (Lakota, N.D.)

A: Yes, the white Annabelles are tougher.


Q: Should I cut down my hydrangeas? They did not do well this year for some reason, so I am not sure what to do with them. Also, is now the time to cut my mock orange? If so, how far from the ground should they be cut? There have been a couple of light frosts, but they still have a lot of green leaves. My husband says I should wait until the leaves fall off, but then we never will get it done. Will it hurt to trim my evergreens a little now? I have one more question. In your column, you listed something that could be used to kill grass in a flower bed, but won't kill the flowers. I could not find it around here and now I lost the name of the product. (e-mail reference)

A: Your husband is right. If you forget again this fall, then do it early next spring. It would be better for the plants anyway. Leave your evergreens alone for now and save the pruning energy for next spring. The material that is the active ingredient is sethoxydim, which is found in a number of grass control products, such as Hi-Yield grass killer.


Q: I love hydrangea plants! I purchased four plants in the early spring. At first, the plants did not do well outdoors, so I replanted them in large containers and put them on my patio on the south side of my home. They receive sun and shade from a privacy fence to the west. They now have beautiful, full green leaves. They retained the flowers that were not lost in the early spring. The flowers have turned a lovely shade of green and rust. They were purple and pink. Should I bring them indoors for the winter or should I plant them directly in the soil on the southeast side of my home (only place left for plantings)? What preservation techniques do I use? Will the color return in the spring or summer when they bloom? (Rochester, Minn.)

A: Plant them where you want and cut them back to about 12 inches. But since you live in the banana belt, you don't want to do that until the end of September or early October, after a couple of good frosts.


Q: I have hydrangea bushes that have a white, fungus-type disease growing on the bark. It is brilliant white in color and clustered over the bark. Any ideas? (e-mail reference)

A: This could be a fungus or cottony cushion scale. You need to determine which or just cut off the infected/infested branches and dispose. Hydrangeas are great at coming back from the crown.


Q: I have two beautiful hydrangea bushes that yield big, gorgeous blooms. However, when I cut them and put them in cold water, they wilt, droop and shrivel within 24 hours. Is there a trick to keeping them fresh? (e-mail reference)

A: For fresh-cut flower arrangements, take long stems and strip off all the leaves. Cut the bottoms of the stems under lukewarm water. Place the stems in water up to the blossoms. It is helpful to finish by misting the flower heads so they will absorb more moisture.


Q: I purchased six hydrangeas about three weeks ago. They are single-flower plants in a pink coloration. Five of the six seem OK, but the sixth is losing its color and looks sick. The flowers are planted next to the house in a mostly shaded area. How can I rejuvenate this plant and how should I fertilize the others? Will they always be single-flowered plants? Will a new bloom replace the existing one or will I have to wait until next year? The shop I purchased the plants from does not have any answers. (e-mail reference)

A: I'd find a new place to purchase plant material in the future. The sick plant may be past saving. Prune it and give it a shot of Miracle-Gro or something similar. These plants will always be single flower. Depending on the type of hydrangea, the blooms may be replaced with new ones. Some cultivars will do both, but only time will tell. Be patient.


Q: About four years ago, I received a lilac bush from my mother-in-law for Mother's Day. The lilac keeps getting better and better, but it has yet to bloom. Each year it gets a little taller and has more and more green leaves on it. I've never done anything to it since it was planted. Should it be pruned? Please help. I'm terrible with plants, but I really want to get better because we're finally landscaping around the new house we built. That leads me to my hydrangeas. I purchased two forever pink and one PG hydrangea that I want to plant in one area and five Sister Theresa hydrangeas to be planted somewhere else. How far apart should I plant them? Any tips would be appreciated. When will they start to bloom? (e-mail reference)

A: The lilac may not be blooming because it is getting too much shade or nitrogen-rich fertilizer. You might be able to stimulate it to set flower buds by driving a straightedge spade into the ground around the edge of the spread of the foliage. Do that in about six places. This mildly shocks the plant into a reproductive cycle. I would suggest planting the hydrangeas about three to four feet apart. They are among the easiest plants on earth to grow. Plant them at the right depth, keep them watered, but not soggy, and they should bloom for you.


Q: I would like to know how to start a new bush from a very old hydrangea bush that my grandmother had. It is at least 50 years old and still growing. (e-mail reference)

A: Hydrangeas root fairly easily from softwood cuttings taken in May through July. Stick them in a sand/peat mix (50/50) and keep them moist. Keep the cuttings out of direct sunlight until they root, which should take six or more weeks.


Q: How and when should I prune my endless summer hydrangeas? (e-mail reference)

A: You can prune your hydrangeas anytime now and prune as much as you want because they bloom on both the old and new growth.


Q: I bought a house with at least 10 hydrangea plants. Approximately 70 percent bloomed last summer. I think some are old-growth and some are new-growth blooms. How do I know for sure what is old or new growth? I'd like to prune the new-growth varieties, but don't want to risk losing the old-growth blooms. (e-mail reference)

A: When in doubt, strike a compromise. Prune half the branches and see what comes, flowers on the new growth or the old. Take notes and prune accordingly each year.


Q: I have tried to change the color of our white hydrangea from white to purple/blue using aluminum sulfate, but have had no luck. Please advise me on how much aluminum sulfate to use and the application procedure. (Detroit Lakes, Minn.)

A: It is not going to work, so give up trying. The hydrangea species it works on, the bigleaf hydrangea, is not hardy to our area.


Q: I have a hydrangea bush that is not doing well, so I would like to move it to another spot. When is the best time to do the transplant? I also would like some advice on red maple trees. Our tree hasn’t grown to any extent since we planted it a few years ago. Should we replace it or is there something else we could do to help it grow? (Gackle N.D.)

A: Move the hydrangea after a couple of hard frosts. The maple could be planted too deeply, which is a common mistake. The crown should be right at the soil surface. The crown is where the stem and root system meet. If your tree is planted to deeply, pull the soil away from the trunk of the tree to where the crown is. That may improve the vigor and appearance of the tree.


Q: I have had a hydrangea for about three years, but I’m not sure what kind it is. The bush is healthy, but it seems to me that only part of the flower head blooms. Maybe six or seven flowers and the rest seem to remain closed. The expert at the local nursery says that it is a lacecap and that is what it does. If this is the case, I certainly got the wrong kind for what I want. What do you think? (e-mail reference)

A: That is exactly what lacecaps do. They have a center of fertile, nonshowy flowers and an outer ring of showy, nonfertile flowers, which provides a nice pinwheel effect that many people like. Apparently, you are not one of them. You probably would like the all-sterile flowers found in hortensias. Dig the present one out and get what you want in a plant. Life is too short to put up with something that falls short of expectations!


Q: I (stupidly) forgot to water my dad’s hydrangea Sargentiana. It was sitting in the sun all day yesterday, so the leaves have wilted. My dad will be back tomorrow. He is a landscape gardener, so he will be mad! If you could tell me the best thing to do for the plant, I would be eternally grateful! (e-mail reference)

A: Soak it in distilled water. The plant will take up the water and respond quicker than any other water with a salt content. If anything, it will rehydrate the plant quickly. Of course, get it out of direct sunlight as well.


Q: Last year we planted an endless summer hydrangea on the north side of our house. It was a very nice, healthy plant, but no blooms. We decided to wait until this summer to see if it would bloom. To date, it’s a nice looking plant, but no sign of flower buds. The Annabelles next to it are doing fine. Does the endless summer need more sunlight? Does it bloom on new wood like the Annabelles? Any tips would be appreciated. Thanks! (Baudette, Minn.)

A: Endless summer has the advantage of being able to bloom on old and new wood, so pruning is not a problem. My guess is that it needs a little more time to mature and then bloom. I hope you are not fertilizing it with a high nitrogen material because that could inhibit blooming somewhat. Be patient. It will get around to flowering for you.


Q: I planted some hydrangeas that are supposed to be hardy for my area. Should I do anything special to them before winter arrives? (e-mail reference)

A: Yes, cut the hydrangeas back to the ground. I do that to my hydrangeas every fall using an old power mower. Do it after the hydrangeas have been frosted several times, but before winter closes in. In your case, you probably can use a chain saw or long-handled loppers to do the job.


Q: I enjoy your column so much. We planted a dark-leaved maple tree last year. It grew fine and had leaves. It is now early June and it still doesn’t have leaves. When we scrape it with a fingernail, it is green. Will it eventually get leaves and grow? The other question is about a blue hydrangea plant my husband gave me for Mother’s Day. I would like to keep it growing. I plan to put it outside when it is finished flowering. Do I leave it in the pot or plant it in the ground? Would I have to bring it in for the winter or could I put mulch around it? What do I use to keep it a blue color? (Watertown, S.D.)

A: If it doesn’t leaf out in a couple more weeks, I’d say forget it. As for the hydrangea, plant it in the soil and fertilize with aluminum sulfate to maintain the blue color. Mulch it well this fall just as the ground freezes. Cut it back heavily early next spring, before new growth begins.


Q: I have what I believe is a white/cream hydrangea bush in front of my apartment that I love. Can I cut a branch and get it to root? I’m moving and would like to try to root my own tree if possible. (e-mail reference)

A: A nonflowering branch will root, a flowering one will not.


Q: I have glowing ember hydrangea bushes. They are growing out of the ground quite well, but all of the old stems are dead and not growing. Should I prune them or will I get growth on the old wood? (e-mail reference)

A: Prune them. Your hydrangea will flower on the current season’s growth. Last year’s growth is dead and is of no use to the plant.


Q: I am painfully inept when it comes to gardening. I have always loved hydrangeas and bought two for the front of my home. They receive full sun daily and face east. I was reading about pruning them in the fall to save them from the winter. How far do you prune? How much watering do they need? How can I save them from me? (e-mail reference)

A: During the last mowing in the fall, I run my mower over the remaining hydrangea sticks. Every spring they come up and bloom nicely for me. Water them sufficiently to keep them from wilting and fertilize with Miracle-Gro when new leaves are forming in the spring.


Q: We have a hydrangea bush that is not in a great location. It isn’t a hardy bush and other bushes are overgrowing it. Little green sprouts are just breaking through the soil now. Is it a safe time to dig up the sprouting areas and move them? Any advice on the move will be greatly appreciated. (e-mail reference)

A: It isn’t the best time, but the transplanting should be a success. Don’t worry if those emerging sprouts wilt because I am sure there are many more that will break and grow if these should bite the bullet.


Q: I am getting married in September and would love to have centerpieces made of purple dried flowers. I have seen dried hydrangea, but do not have any in my yard. I do have a large lilac bush. Do the blooms dry as nicely as hydrangea? Will they retain their color? Do you have any suggestions on large-headed flower varieties that I can dry and inexpensively display, but still look elegant? If I plant hydrangea, I doubt it would grow and produce the large quantity I need in time for the wedding. Is hydrangea easy to grow? How long does it take hydrangea to mature? (e-mail reference)

A: I am sending a copy of your message to my colleague, Barb Laschkewitsch, for a possible response. She is a florist by training and is a very educated and knowledgeable horticulturist in the area of drying flowers. You can purchase hydrangea while in flower, which is a good idea because you then will know what you are getting. Give them a few years to grow. In most landscapes with ample sunshine, you will be awash with beautiful flowers. Congratulations on your upcoming wedding. May you have a lifetime of happiness and fulfillment!


Q: I have a blue hydrangea (endless summer variety) that I would like to fertilize with aluminum sulfate to encourage blue flowers. How often should I fertilize? (e-mail reference)

A: Fertilize it once a month during the growing season.


Q: Why would hydrangea plants stop blooming after several decades? What makes it odd is that the plants are located far apart and in different gardens. I didn’t do anything different than before. I get plenty of foliage, but no blossoms. They don’t seem to have any disease. Any ideas? (e-mail reference)

A: It could be an improper pruning schedule, overfertilization with high nitrogen or too much shade.


Q: I have three hydrangea bushes that grow quite well each year and stay full and green through the season, but they do not flower. They are the big-leaf type hydrangea. I do not prune them, but I cut off anything that looks diseased or has become damaged over the winter. After reading some of your answers to people with the same problem, I am guessing that my problem is that they are getting too much nitrogen because of lawn fertilizing. Is there anything I can do, other than moving them or quit fertilizing the lawn, to help? (e-mail reference)

A: Try my old “traumatic stimulation” procedure, which is the cutting of some of the root system by inserting a straight-edge spade into the soil in several places around the edge of the foliage spread. This often shocks the plant into a reproductive cycle. The plants may be in too much shade. Plantings on the north side of a house typically are void of flowers. If that is the case, you should move them to a sunnier location for good flower production. If the problem is too little light because of tree overhang, try to open the canopy to allow more light to reach the plants.


Q: I just purchased a hydrangea plant with several beautiful, blue blooms. When should I plant it outside? Does it require special care? Can I separate it into two plants before I plant it outside? (e-mail reference)

A: This may be a florist hydrangea and not hardy enough for outside planting, but nothing ventured, nothing gained. Try planting it outside after the danger of frost is past. Use a soil mix rich in sphagnum peat moss. To maintain acidity, fertilize once a month with aluminum sulfate. If it comes back next year, you’ve got it made!


Q: We have three large hydrangea bushes with many greenish blooms. I did not know how or what to do with them before winter came. They look the same, except the blooms are now beige/brownish. They have large leaves and look almost out of control. When should they be pruned and how far back do I cut them? I hope it’s not too late to do anything. Can anything be added to the soil to get the blooms to come out pink or blue? (e-mail reference)

A: I would suggest cutting them back hard to 6- to 9-inch stubs. Cut the bushes back early this spring, before new growth begins. Adding acidifying fertilizers will help bring out a blue bloom. There are almost as many hydrangea species as there are Smiths in the local phone book, so this is a generic recommendation. It’s analogous to a doctor saying take two aspirin tonight and, if you don’t feel better in the morning, get back in touch. If this doesn’t produce a better plant with more attractive flowers, get back to me and we’ll try to dissect the problem further.


Q: I am currently planning my wedding. I am going to have hydrangeas on the tables for the reception. I want to give all of my guests some seeds as a gift, along with a contribution to a memorial fund. The idea is to have the plants grow in memory of those who are no longer with us to celebrate the wedding. What type of hydrangea would be the easiest to grow for the novice horticulturist? What is the best way to order seeds in bulk? (e-mail reference)

A: That is a good question and a noble undertaking on your part. Go to www.iloveplants.com/html/Plants_and_Seeds/
Ornamentals/Plant_L2K_Seed_Sources/

to contact potential nurseries that specialize in hydrangea production. You might start out with Bluestone Nurseries out of Ohio. Good luck and best wishes!


Q: Can you please give me a tip for extending, beyond one or two days, the life of Annabelle hydrangeas? I have flowerless neighbors who could sure use some of my excess. (e-mail reference)

A: Hair spray usually works quite well. Fog it over the head of the flowers. You can also acidify the water with unbuffered aspirin. The aspirin will keep the stems from plugging because of bacterial development. Florists usually have several materials available that are effective in extending the life of flowers.


Q: I have a cluster of grapes on my desk that appears to have mildew, but I’m not sure. They are covered with a white powdery mold and the fruit is shriveled. Also, if I overfertilized some hydrangeas with manure, what would happen? (Forman, N.D.)

A: The problem is most likely downy mildew. It is very destructive on grapes. Overfertilizing hydrangeas will result in excess vegetative growth and reduced flowering.


Q: Last year I purchased a nikko blue hydrangea that has not turned blue. This year it is a light pink. I heard Miracid will change the PH level and help turn it blue. Is this true? I also heard aluminum and copper is good, but nobody has any. (e-mail reference)

A: You need to find aluminum sulfate somewhere. It will drop the pH to below four, which is where it needs to be to get your hydrangea to turn blue. Try straight sulfur and work it into the soil if you can’t find any aluminum sulfate.


Q: I recently planted a blue Dooley hydrangea. It produced beautiful blue flowers for me several weeks ago, and now they are starting to turn green, mauve and some brown. Does this mean they are almost done flowering? When should I cut back the blooms and how far? Should I expect more flowers this year? Also, it seems the flower heads are too heavy for the stems and they're droopy. We've been getting a decent amount of rain lately, so I haven't been watering the plant as much as I did in the first couple of weeks after transplanting, when it was really hot and sunny. I have it in a corner in front of my townhouse, so it gets morning shade and some direct afternoon sun. Do I need to water it more to prevent the droop? Should I stake it up? Does it need fertilizer? If so, what kind? Incidentally, the cutting I took from my sister-in-law's hydrangea last year is blooming, but it blooms pink at my house and darker pink/purple at hers. Could my blue hydrangea be changing colors due to soil acidity changes even after the blooms are mature? (e-mail reference)

A: Cut them back and you should get another bloom out of them. You may have to put a peony hoop around the drooping blooms. Sometimes there is too high a nutrient level in the soil from lawn fertilization that the stems are not strong enough to hold themselves up. I have taken cloth straps and tied them up at times when the peony hoop was too small. The difference in color of the flowers is due to the difference in the soil pH - acidity/alkalinity.


Q: I recently purchased a hydrangea bush and planted it in front of my house. I’m starting to notice that many of the leaves are turning yellow and wilting. However, there does seem to be new growth on the top and I see flower buds starting to form. I did everything the nursery told me to do. We have had a lot of rain recently, so the soil is damp. I am afraid that the whole plant is going to die. I have not fertilized because the instructions with the plant directed me to wait. (e-mail reference)

A: Contact your local nursery and tell them what is happening to your plant. I think the plant will come out of its funk when the rains let up, but it wouldn’t hurt to check with the folks who sold you the plant.


Q: I ordered six ruby red hydrangeas from Springhill Nurseries. One is now blooming, but the bloom is pink, not red. If I had wanted pink, I could have purchased them right here in town! (e-mail reference)

A: The plants probably need a little more lime. A lime application will help darken the color, but test your soil first. I'm willing to bet it is on the acidic side, with a pH level below six. Also, this particular cultivar starts out pink, but darkens gradually through the season. It should turn a deep carmine pink, or red as some prefer to call it.


Q: I purchased two hydrangea hobella plants three years ago and planted them in front of my home. They get some morning sun. They flowered the first year, but haven’t since. The tag that came with the plants states that this plant is as hardy as other hydrangea macrophylla and can sustain temperatures to zero degrees. What can I do to get the plants to start flowering? Someone told me to prune them back, which I did this spring. After reading some of the advice you gave others, I don't think I should have! (e-mail reference)

A: Lucky you! These are hard to find plants. Actually, you should not have pruned them according to the Spring Hills Nursery folks. They recommend nipping them back after the blooms are finished. It apparently sets flower buds on the previous season's growth, so a spring pruning would wipe out any flower buds that were set last summer. They claim this hybrid is hardy down to 10 below.


Q: I have a creeping hydrangea that has been trained to climb an iron lattice. It gets half-day sun. This is my third year without blooms. This spring it grew more vigorously, but still no flowers. Any advice? (e-mail reference)

A: Be patient. The vine will bloom when it reaches maturity. For now, it is enjoying the vigor of its youth by remaining vegetative and attempting to cover as much area as possible. You can encourage maturation by driving a sharp-edge spade into the ground in a couple of areas to sever some of the roots. Also, don't be generous with high nitrogen fertilizers. These actions, combined with patience, should result in flowers next season.


Q: I recently planted a blue hydrangea. After planting, we had a cold snap and snow. Two of the three branches turned brown while the third is still a beautiful blue. How do I prune the brown without killing the plant? Will they blossom again? (E-mail reference)

A: Cut the flowers back that were affected by the cold snap. The plant will flower again next spring.


Q: I received some hydrangea cuttings from my grandmother, which I would like to start growing to keep hers alive. I cut them this past Saturday and they are in a vase with water. Can I still start new growth with a peat and sand mixture? (E-mail reference)

A: They might if you take them out of the water, make a fresh cut across the base, dip them into a rooting powder and then stick them in the sand and peat mixture. The best and easiest rooting takes place if you use cuttings taken during May or June.


Q: Can the mineral content of the soil be adjusted to get a different color hydrangea? (E-mail reference)

A: Yes, but only on a particular species of hydrangea, the bigleaf (Hydrangea macrophylla). Aluminum sulfate will make the soil acid and give the flower a blue hue. Adding limestone will make the soil pH more alkaline and turn the flower pink. Have fun trying but don't have high expectations for good coloration.


Q: My new hydrangea bushes have black spots on the leaves. One source I read recommended overhead irrigation, another says no. One says apply nitrogen to soil. Can I remove all the effected leaves without killing the bush? Fungicides make me nervous and I have a lot of pets. (E-mail reference)

A: Do not do overhead watering. Contact the local garden center and see if you can find some Schultz products. They have a product called Fungicide 3 that is made with neem oil and approved for organic use.


Q: I recently received a blue hydrangea for Mother’s day and would like to move it outside. The flowers are starting to die back. The blooms that are still on the plant are turning green. I drench it thoroughly when watering but let the excess run off. It is still in its original container. Where is the best place outdoors to plant it and what type of soil does it prefer? Can I leave it outside for winter? (Mazeppa, Minn.)

A: Move it to where it can get some sunlight but not direct all-day sun. Dappled shade is best. It will probably not survive the winter in Minnesota, so consider it a brief gift to be remembered or bring it inside for the winter. The flowers turning green is natural and nothing to worry about. Remove the flowers when they turn brown.


Q: The crew that sided my house trampled my hydrangea. Any hope it will come back? It is a very large leaf variety with pale green blooms and, I think, quite old. (E-mail reference)

A: Thoughtless guys! But I’m willing to bet that you will get a regrowth this spring and in a couple of years the damage will only be a memory!


Q: We have two hydrangea bushes on the west side of our house. They seem to be growing out of control. They are so big and heavy that they droop over so that the flowers are on the ground. I don't know what kind they are and am wondering if it's too late to prune them this year. Will pruning prevent them from drooping next year? Thanks! (Savage, M.N.)

A: It can't hurt. Give them a good pruning before winter arrives. They bloom on the new growth produced next season.


Q: How do I get a start off my neighbor's hydrangea bush? (E-mail reference)

A: Ask first, of course. Then take softwood cuttings from the May, June, or July growth, and root in a 50/50 sand/peat mix, under mis


Q: Could you please tell me how I can start a new hydrangea plant from cuttings of my present one? (E-mail reference)

A: Softwood cuttings root from May, June or July growth; semi-hardwood cuttings will also root with a little help from a rooting compound like IBA. Peat/perlite mix works well, as does a peat/sand mix, both under intermittent mist.


Q: How do I prune back my hydrangea, and when do I do it? (E-mail reference)

A: I will assume you are talking about the Annabelle hydrangea. Prune it in the early spring before it comes out of dormancy, back to about 4- to 6-inch stubs.


Q: I received a small, white blooming hydrangea bush around Easter 2000. I planted it soon after. This past summer of 2001 it did not bloom. Perhaps it was getting too much afternoon sun as the leaves wilted often. I recently moved it to a less sunny spot, gave it good soil, and mulched. It appears to be doing better now. Can I expect blooms next summer? Would a fall application of fertilizer help? (E-mail reference, southeastern Pennsylvania)

A: Try to find out what kind of hydrangea it was. It will probably not flower for you next summer, because it may be the type that has flower buds that are not hardy enough to survive Pennsylvania winters, and all you will get is the foliage. That is often the case with florist hydrangeas.


Q: I have a problem with my blue hydrangeas. They have been planted for two years now but I can not seem to get them to bloom. They are in an area that has a lot of shade, but some sun light does get through. I water them regularly. Have you any clue as to why they aren't blooming? (E-mail reference)

A: Some reasons why hydrangeas fail to bloom: 1. Improper pruning. Some bloom on old wood, some on new season's growth. For example, the H. arborescens cultivars (like the popular 'Annabelle' in our region) bloom on new growth and are consequently best cut back hard in the early spring. By contrast, the H. macrophylla ( Bigleaf hydrangea) will grow as far north as central Illinois and South Dakota but will not usually flower because the flowers develop on old (last season's growth) wood. Since flower buds lack the cold hardiness of the foliage buds, they are often killed out, while the foliage lives on. In other words, you could have the wrong plant for your location. (I have no idea where you are writing from!) 2. Way too much shade. While they will do all right in partial shade or full sunlight, too much shade could keep them from flowering 3. Too much Nitrogen. If the plant is adjacent to a lawn that gets a regular dose of fertilizer, the high N content in typical lawn fertilizers could keep it from flowering. If you have the Oakleaf hydrangea (H. quercifolia), it could be that the terminal bud is winter-killed every year, being the source of flowering for the upcoming season. In the south, this is a beautiful flowering plant, even as far north as Columbus, Ohio, but elsewhere it might only be able to produce foliage.


Q: My house faces north. I planted a hydrangea on the north side two years ago and decided to move it to the south side, which I did last fall. It came up in spring but hasn't done anything. The leaves are a pale green but it only grew about 6 or 7 inches tall. I was wondering if I should move it back to the north side. So far I haven't had any flowers on it. (Winnipeg, Man., Canada)

A: From your description, I am willing to bet that it is planted too deep. Hydrangeas are fairly adaptable to the south or north side of buildings, with the south side requiring a little more vigilance in applying water and fertilizer due to the higher sunlight and heat loads. If you want to keep it in the new location, I'd suggest replanting it at a little shallower depth this fall when it has gone dormant.


Q: You or a reader answered a question about drying hydrangeas. You didn't mention a time of day to pick them. I picked mine in the early evening and they were big, beautiful and blue. I hung them in my laundry room, which is dry and dark, and they dried into shrivels. Did I pick them the wrong time of day? (E-mail reference)

A: Not so much the wrong time of day, but perhaps too soon in their development. Wait until the flowers are nearly fully mature, then pick them in the early morning hours (like 6 or 7 a.m.) or in the evening hours just as the sun is setting. You can hang them upside down, or you can put them in a vase with just enough water (about an inch or so) to get the ends into and simply let them dry down naturally.


Q: When we bought our house three years ago there were four large hydrangea bushes along the east side of our garage, which also has a huge pine tree for shade. The bushes grow so large that they must be staked. We have never pruned them as we weren't sure when the best time was. They have huge leaves and very long flower heads that are an off-white and pink. I have never seen anything like them in books or in nurseries. Is it possible for you to tell us their name and how to take care of them? We live in the southwest part of Ohio. (E-mail reference, Ohio)

A: Thanks for telling me where you live. It helps me to focus on what the plant might possibly be, and in this case, I think it might be the oakleaf hydrangea ( Hydrangea quercifolia). If I am correct, it should be pruned right after flowering, generally in early August depending on your location and microclimate. I wish they were hardy here in North Dakaota. We had many beautiful cultivars on the Ohio State campus when I was there in the '70s.


Q: I just purchased a wonderful Lace Cap hydrangea. My question, is can I keep this amazing shrub alive in a container to enjoy at work with me? I live in Las Vegas, Nev. and do not want to subject this wonderful plant to such an environment. I would love be able to enjoy it's beauty at work with me, but do not know if it will survive as an indoor container plant. (E-mail reference, Las Vegas, Nev.)

A: Lace Cap is a cultivar name of the species that is typically used as containerized plants for indoor settings. This plant has two basic needs: cool conditions (ideal in a air conditioned environment) and to not let the soil dry out between waterings. Once the flowering has passed, cut the stems back to half their original height. After flowering, repot and continue to water and fertilize. In your hot location, keep indoors in summer and move outdoors on frost-free days in winter. Somewhere in between there will likely be a need for a rest period. When the plant starts to fade, cut back on the watering for a period of about six weeks, then begin the cycle again, keeping it in bright light but never direct sunlight.


Q: I have an "angel’s blush" Morovian hydrangea. The leaves are turning brown and crisp around the edges. I have given it Mir-acid, and it is planted on the north side of my house. What can I do to get rid of this problem? I am enclosing a couple of leaves for you to look at. (Portland, N.D.)

A: It appears to be salt burn, drought stress, or soil compaction symptoms. In other words, an environmental stress rather than a pathogen. Try laying off the fertilizer and leaching with water to see if it improves.


Q: I noticed several people asked you for tips on how to dry hydrangea blooms. Might I humbly offer a suggestion? I have found that it is best leave the bloom on the plant itself until the flowers begin to fade and look as though they are drying out. If you pick them earlier when they are at their brightest and freshest it seems to cause them to wilt and shrivel up very quickly. I don't know why this is, but time and again I have lost flowers I wanted to dry for cutting them too early. With patience I have been able to create beautiful dried arrangements. Also, it is not necessary to hang them upside down as you would a rose. Roses are hung that way to insure a straight stem when completely dry, but hydrangea stems seem naturally stiffer. You can just put them in an empty vase and let them dry on their own, they will hold their shape if they weren't cut too early. (E-mail reference)

A: Thank you for your humble suggestion! I am sure the readers of the column will appreciate getting the information first hand from one who has had ample experience.


Q: I was interested in your comments regarding aluminum sulfate and lime for colors of hydrangea. Is it too late to apply now ? Do we buy these fertilizers at a nursery or are they available at discount stores? Also, do your simply apply around base of plants and water in? (Detroit Lakes, Minn.)

A: The applications are more effective if applied prior to new growth beginning, and they are materials that one usually can obtain at local garden centers or supply stores. As a rule of thumb, a heaping tablespoon of lime sprinkled under the canopy and watered in, and a tablespoon of the sulfate per gallon of water and watered around the soil will do the trick. If not, then add a little more until you get the coloration you want.


Q: This is the third season for my hydrangea. For three years the flowers have come up but will not flower. Last year the nursery I purchased them from suggested cutting them back, which I did, and still the same results. They said fertilization on my lawn produces too much nitrogen. I don't fertilize my lawn. I live in the country with no neighbors, so nothing there either. They are on the north side of the house, so now they are telling me it's too shady. They sold me these because it was the north side of my house. They say too much water, not enough water, blah, blah, blah. Seven big beautiful plants, three years invested and no blooming. Help, please. (E-mail reference, Iowa)

A: Annabelles bloom their beautiful heads off all over North Dakota and I see no reason why they shouldn't do the same thing in Iowa! Possibly they are in too much shade. While they will tolerate some shade (mine are planted somewhat on the north side of our house too), if they don't get some sunlight during the day, their blooming will be very poor or in your case, non-existent. They also like to be kept moist--not wet--and bloom on new wood, so pruning in late fall or early spring right to the ground will do the trick. If they fail to bloom after this, I suggest moving them to a sunnier location. Anticipating your next question, here is a brief list of some shade tolerant shrubs that will grow in Iowa, as well as all over the upper midwest: Amur maple, serviceberry, many species of dogwood, bush honeysuckle, pin cherry, scarlet elder and viburnums.


Q: I absolutely love Hydrangeas and would like to find out to what variations of colors are available. Are there certain hybrids that have certain colors? (E-mail reference)

A: The colors are often a result of a dye the florist has put in the water prior to retailing them. True colors can be switched back and forth between pink and blue by using lime for the former, and aluminum sulfate for the latter.


Q: For Mother's Day, my son gave me a beautiful hydrangea plant with gorgeous lavender flowers. I live in an apartment and am not able to plant it outside. It is still blooming and doing fine. Any suggestions for keeping it indoors? (E-mail reference)

A: If you can, summer it outdoors on a patio or porch. If not, try to keep it evenly moist. Use rainwater or deionized water if your tapwater is hard. Mist the foliage often. Once it is done flowering, repot and overwinter in a frost-free room, watering sparingly. Around the first of February move it to a brighter location, increase watering and give it a shot of fertilizer.


Q: I have a beautiful hybrid hydrangea plant, the ones that have the ruffly, beautiful leaves. The blooms are just gorgeous and dark pink. I wouldn't change it at all, but I have one of the older types like Mom used to grow about 5 feet from it. The pink flowers are washed out in color. My old friend added something to the soil and changed hers to purple, and Mom could change hers from pink to blue, by adding something. Do you know what I can do to change my faded pink hydrangea to purple or blue? (E-mail reference, Louisiana)

A: You can make the colors on a hydrangea move by using a sulfur-based fertilizer like aluminum sulfate to get the purple/blue color and lime to get the pink color.


Q: We have a hydrangea bush as part of the landscaping under our east picture window. Because of the hydrangea's location, we need to keep it pruned. I am wondering when is the best time to prune it so as not to affect the blooms. How severely can we prune it? Last year it had just three clusters of flowers on some lower branches which had not been cut. (Milbank, S.D., e-mail)

A: Since hydrangeas flower on the current season's growth, you can cut it back to the ground now, or late fall next year when that season is past. The flush of new growth that will result the following spring will (or should be) loaded with flowers for your enjoyment!


Q: I have a beautiful hydrangea in front of my house and I would like to break it apart and put some in another location. I know the best time to do it is in the fall, but can I still do it in the spring? (e-mail)

A. Since hydrangeas flower on current season wood, you will lose nothing by transplanting it in the early spring. So go ahead and move it. These are tough plants--almost impossible to kill. If you are really in love with this plant, you can take softwood cuttings from it in May, June or July and root them easily in a sand/peat mix.


Q: I've just started gardening for the last three years, and I've searched our libraries, spent a fortune in books, made notes etc., but sometimes I can't find an answer to a specific question. I'm in Pennsylvania, zone 4 to 5-ish, and I have a beautiful hydrangea bush (nikko blue) that I love. I really want it to survive the winter, how do I get it ready?

And while I have your "ear" ... I've tried identifying a bush but haven't had any success. The structure of the plant is similar to aorsythia, the stem is green/brown in the summer and red in the winter, the leaf is variegated, not waxy, almost papery feeling. It does flower (briefly), a very tiny cluster of flowers that are vaguely similar to a Queen Anne's Lace flower. Any ideas? I need to figure out how to prune this bush and how to take care of it. Oh, yeah, and its name would help too! (Pennsylvania e-mail)

A: The zone you are in should not require any special treatment for winter. However, if you want to play it safe, mulch the crown with straw mulch 4 to 6 inches thick. Prune back hard in early spring prior to new growth starting!

The plant you are talking about is likely the variegated leaf dogwood--Cornus alba Aurea is the likely botanical name. Simply cut the oldest canes at the base each year to stimulate new, red-twig growth.


Q: Is there any way to keep the flowers on my Annabell hydrangeas white longer? And can you tell me why my wild rose is not blooming? (Moorhead, Minn.)

A: As far as I know, there is no way to extend the white color of the Annabell hydrangea, and the wild rose is probably living too good a life. Don't fertilize or water it, and drive a straight-edge spade in the ground in three places around the plant. This severs some roots and may cause it to flower. If none of these work, yank it out!


Q. I have a snowball bush, and I would like to trim the top down. When is the best time to do that, and will it hurt the bush? Will this stop the blossom from coming on the top? It is beautiful now, but I would like to keep it at a medium height. I really enjoy reading your column. (Walcott, N.D.)

A. The snowball (I assume you mean the Hydrangea) should be pruned in late winter or early spring, as it blooms on new growth. Unless you are willing to give up some flowers, now is not a good time to prune.


Q. Do I have a serious problem with the enclosed branch from my snowball tree? Is this a disease? Can it be controlled? (Tuttle, N.D.)

A. Your hydrangea sample was "buggy" with green peach aphids and the larvae of hydrangea leaftiers. I suggest an immediate spraying with Orthene or a similar systemic to control the population somewhat. Other than that, the plant appears to be free of disease symptoms.


Q. I have a snowball bush that was cut off by mistake, and now the blooms on it seem really small. Will it get big blooms on it again? Also, is there more than one kind of potentilla? I saw one with really large flowers and would like to know what kind it was. I have one that blooms a lot smaller, but I like the larger flowers. (Walcott, N.D.)

A. Don't worry, your snowball bush will be just fine—just don't cut it back so late next spring!

There are many Potentilla cultivars on the market. Yellow, white, red, big blooms, small, etc. I count some 56 selections in my reference books. What you saw was likely the Jackman's variety. It has yellow flowers ¼ inch to 1½ inches in diameter. Yours could be the Gold Drop form—a little smaller.


Q. Thank you for all the useful information you give us all in the Farm Forum. Your column is the first I turn to when the "Green Sheet" arrives!

I am enclosing a sample from a white pine (Pinus strobus) that was planted in June of 1994. Right now it is about 5 feet tall. For the last two years in the spring the tree needles are completely brown like it has died. Then all summer I feed  Mir-Acid and get it to green again. Does it have a disease I could spray for?

Also I am enclosing a sample from a pee gee hydrangea that was planted July 6,1997. There were two bushes planted at the same time. This year one bush had many blooms on it, but the other is not blooming at all. I have examined the leaves, but  cannot see signs of insects and the plant looks very green and healthy. Could you please advise me as to what I could do to get this bush blooming again.

Thank you for your time. (Grenville, S.D.)

A. Your white pine has nothing wrong with it. I am afraid that will be the nature of the plant since it is growing where it shouldn't. Continue doing what you have been and you should be able to enjoy the tree for many years.

Concerning your hydrangea--the only guess I can make is that the non-flowering one may have been pruned too late in the growing season, or it is in too much shade. From the looks of your sample, growth and leaf size appear normal, so it could be a pruning problem.

Thank you for being a fan of Hortiscope. People like you make it interesting.


Q. I read your Hortiscope advice column in the Farm Forum from Aberdeen and have found some very helpful articles.

I have a snowball bush which I just planted this spring. I have it in the center of two peony bushes and it is doing well. I am wanting to move it from the present place ask is it advisable to move it this fall and also, where is the best place to plant it? I also received four Stella D'Oro plants this past week should I plant them near each other now or wait till later this fall?

Thank you. (Woonsocket, S.D.)

A. Plant the snowball this fall after it has gone dormant and water it well. It will do best in a sunny location.

Plant your lilies as soon as possible and enjoy.


Q. I have a snowball shrub that was accidently cut off, but since then, it has come up from the root. There are about six stalks about 3 feet tall and lots of growth around the bottom. It has never blossomed since, which was three years ago.

What should I do with it? Will it ever amount to anything and blossom again?

It is very healthy looking and I have given it Miracle-Gro.

I enjoy your column and have gained a lot of information. (Walcott, N.D.)

A. I cannot be sure of what you mean by the name "snowball" shrub. To me, it has always been the Hydrangea paniculata 'Grandiflora.' To others, it means one of the viburnums.  Either way, if it has failed to flower after three years, I would either replace it or enjoy the green beauty it provides.

Thank you for the nice compliment about the column!


Q. Enclosed you will find a small branch from my snowball tree. The last two years it has not bloomed. This type gets red berries after it has bloomed. It now gets green berries and they turn black. It almost looks like a chokecherry tree. This really got messy when they fall. I would appreciate any help you can offer.

The bush was here when we moved in, which was 1955. It has always been full of flowers.

Enjoy reading your garden tips. They are always helpful.Thank you. (Enderlin, N.D.)

A. I do not know why your plant has changed, unless it has sprouted from the base, below a graft union, and that is what you are witnessing.

The sample you sent in was pretty well inoculated with rust pustules, so there must be some oats growing nearby--the alternate host to this plant.

By the way, I do not know what you mean by the snowball tree. The sample you sent was from a Rhamnus cathartica, common buckthorn. If you didn't plant it, the birds did!


Q: I bought a big-leaf hydrangea and kept it in morning sun, afternoon shade and gave it a little bit of plant acid since I was planting it in alkaline soil. It went downhill since the transplanting. The nursery told me to plant it outdoors. I also bought another hydrangea (nikko blue); I have it planted and it's just going down hill. I try to water only when the soil is feeling dry on top. I also bought a lace cap hydrangea, which I've kept it in the container I purchased it in. I have tried to move it to three different spots every day, but the plant just gets dryer and dryer. (California e-mail)

A: I suspect the water you are using may be too salty. Do you have a water softener connected to your water supply? If so, that's the reason. If you don't, then there are some other possibilities. First, you may simply be getting the wrong speciesflorist type rather than landscape types. Second, try north-side plantings; even the morning sun may be too strong. And finally, go for the Annabelle cultivar--Hydrangea arborescens. It is hardy from Georgia to North Dakota. If that one doesn't make it in your area, give up and try something else!


Q: I was told that it was possible to cut and dry hydrangea flowers to use as a bouquet, but I can't find anyone to tell me how to do it. Is it possible, and if so, how do you go about it? (Breckenridge, Minn.)

A: While not pretending to be an expert, I've seen many attractive hydrangea bouquets simply air dried. Harvest the flowers and hang them upside-down in a warm, dark room. When I used to teach landscape design to architecture students, many of them would use dried hydrangea blooms as "trees" in their scaled three-dimensional displays.


Q: We just moved and there is a hydrangea in our backyard. Can I begin a new plant with a cutting, and if so, how? (Sacramento, Calif., e-mail)

A: Yes, hydrangeas can be propagated by cuttings quite easily. Take cuttings from this year's growth--about 6 to 9 inches long--and stick them in moist sand, misting frequently. If you can, get some rooting-up hormone (IBA etc.) and dip the cut ends into that material before sticking the cuttings into the ground. That way, the rooting will be accelerated and should take no more than about four weeks with this plant species.


Q: If you have any info on drying hydrangeas, please send. We have five beautiful plants; we would like to dry some for enjoyment this winter. Thank you. (E-mail reference, Edmond, Okla.)

A: You couldn't have picked an easier one to dry. Simply collect the blooms you want on nice long stems, cluster into bundles of five or six, tie with a rubber band or twine, and hang upside down in a dark, warm, dry place (like a garage) for about two to three weeks until the moisture is out of the plant material. They are then ready to use as dried flowers in arrangements. Some folks will spray them with hair spray to preserve them longer.


Q: I have a hydrangea bush that means the world to me because it belonged to my grandmother, who passed away a few months back. The place is going up for sale and I just gotta figure out if there's a way I can take a piece of it and start a new plant. It seems like I remember her taking a cut off the bush and just putting it in water and the roots took off. I'm trying that now. Do you think it'll work or is there a different method? (E-mail reference)

A: That should work. You can also root them in moist sand or a 50/50 sand/peat mix.


Q: In several of your answers on hydrangeas you state that they flower on current year growth, so people can prune them in the fall. This is not true. Only two species of hydrangeas flower on current growth, like the Annabelle and paniculata. The overwhelming majority of people grow H. macrophylla, which flowers on last year's growth. It will be severely affected by a late freeze or pruning. (E-mail reference)

A: You are right about the H. macrophylla- - the bigleaf hydrangea; it should be pruned right after flowering. If I lived in Georgia I would agree with you, this being a common selection for the south and coastal areas of the country. But, being in the Northern Plains I'll have to stick with what I have recommended, as the bigleaf hydrangea is not hardy in our area.


Q: A lady who has a hydrangea is wondering when is a good time to cut it back and transplant it. I'm guessing you can transplant any time, but is it a good idea to trim one back? (E-mail reference, LaMoure, N.D.)

A: Hydrangeas set flower buds (at least the ones that grow in our part of the country) on the new growth next spring. She can dig and transplant when the plant has gone dormant. All the leaves should be off before attempting to move it. If she missed the fall window, she can catch it next spring before new growth begins.


Q: I have two azalea plants, one magnolia, hydrangea and other smaller plants which I know I have to mulch to keep over the winter. When is the best time to mulch these plants and with what type of mulching material? (E-mail reference, Jamestown, N.D.)

A: Mulch should be applied right after the soil freezes, but before the tough winter weather arrives. Now this makes an assumption that both you and I know doesn't always hold true in North Dakota; that the soil freezes first before the snow cover gets here. As to what to use; dried grass clippings, clean oat, wheat, or flax straw, or if you can get it, salt marsh hay. Many people successfully mulch with tree leaves. Or in some cases, branch boughs from evergreens.


Back to Flowers Menu
Back to the Hortiscope Table of Contents