September 6, 2001

Hortiscope

Ronald C. Smith, Horticulturist
NDSU Extension Service

Q: I have a large flower garden that I want to transplant to a different part of my yard. There are many different flowers ranging from daylilies to tulips, columbines to irises, plus many more. When is the best time of year to tackle this project and do you have any suggestions to make it more successful? I also want to move my raspberry patch and was wondering when I should do this and which plants should I choose to move. Some new plants came up this spring that are now 3 feet or more tall, and there are also plants that just came up within the last month or so. When is the best time to prune out old plants? My 9-month-old daughter loves to be outside, but with all the rain lately, mushrooms are starting to grow in the lawn. I try to pick them before letting her play, but I'm afraid she'll still find some and eat them. Are they poisonous? (Woodworth, N.D.)

A: Here are some good rules of thumb to follow when doing any kind of transplanting. Always, unless absolutely necessary, transplant when dormant (not actively growing) in either the early spring or fall (after a few hard frosts). Anything that flowers in the spring is better transplanted in the fall; anything that flowers in the fall is better transplanted in the spring; something that flowers in midsummer, it doesn't make any difference. Move as efficiently as possible between digging and transplanting to a new site. I suggest having a bucket of dilute solution of Miracle-Gro handy for holding the transplants until they get to their new site. Always select the newest canes for transplanting. They will tend to be more disease-free. Cut the old canes out as soon as they are finished bearing fruit. Rule: Any mushroom that you cannot identify positively as being edible is considered poisonous! Knock them out with a golf club or mow them off before your daughter gets to them.

Q: My neighbor planted two silver maples in his backyard, one about 20 feet from my house. I heard that this type of tree could seriously damage my house drain system and foundation. Is it really true? If so, I would like to convince my neighbor to cut them, which is a delicate task. (E-mail reference)

A: How old myths die hard! The silver maple has problems as all trees do, but foundation destruction and getting into drainage systems are not two of them. Tree roots will follow the path of least resistance, and where a balance of nutrients, water, and air exist. Any tree roots will enter the drain tile that leaks. In the "old days," about this time in the last century, drain systems were in fact made up of ceramic tiles, which could shift and crack, allowing the fluid which many tree roots found to their liking to seep into the soil. The roots then entered the tiles themselves and plugged them. When this became commonplace, the Roto-Rooter Man became popular and a new service industry thrived. Nowadays, the Roto-Rooter Man cleans drains not of roots, but lint and other stuff that seems to back up in some of our drainage systems. Let the trees live! They will mature and shade part of your property as well as your neighbor’s. Enjoy their silver-backed foliage and beautiful fall color.

Q: Tordon was put on a tree stump to kill the tree. After the kill some tree grinders ground the stump up but didn't clean it up. This is an older lady's tree, and her grandson was here this spring. To be helpful he worked the ground tree stump into her flower bed. She planted annuals twice this spring and both times the flowers died. What can they do to make this a useable flowerbed again? Do you suggest digging out the old dirt and filling in with new? How deep would you need to go? On ground where Tordon was applied, how long before anything can be grown again? They also used Tordon to kill their caraganas and would like to plant grass where the caraganas were. (Stanley, N.D.)

A: Tordon (picloran) has long residual times that can stretch into years. I really cannot give you a time line. Two options exist: Remove the soil as you suggested, going down 4 to 6 inches and replacing with new soil. The question is, where will you dump the contaminated soil? Be sure to think that through before taking action. The second option: add activated charcoal to the affected soil. This will help to absorb the Tordon. Tell her to try planting the grass seed in just a small part of the treated area to see if it germinates and lives. If it does, then it is safe to proceed.

Q: I have a cotton-less cottonwood tree that I planted last year. The tree is growing extremely well, although I am unhappy that it is not full. The tree is growing straight up and very slender. It has grown about 7 feet this season. Is there any way that I can make the tree become fuller, such as pruning the main trunk? (E-mail reference)

A: Yes, pruning the tip will cause the tree to lose the strong apical dominance that it is now exhibiting, giving the lateral branches an opportunity to grow and spread. I suggest doing it early next spring before the new growth emerges. Doing so now might encourage too much succulent growth that may not harden off before winter. Besides, the tree would be more susceptible to disease organisms at this time as well.

Q: I just recently had sod installed and there is a fair amount of quackgrass in the Kentucky bluegrass. We are wondering how to treat this problem as well as how soon we can treat it. We just had the sod installed in June and it has completely rooted. I am having a really hard time finding information regarding the treatment of quack in Kentucky bluegrass. (E-mail reference)

A: The reason you are not finding any information is because there is no selective control available. However, I doubt that you are having a quackgrass problem. Sod growers are fastidious about preparing their soil and making sure there are no rhizomatous weedy grasses or broadleaf weeds in the soil they are intending to use as sod. I would more likely think it is a case of misidentification, and is an annual grass, like crabgrass or one of the foxtails. These often come up between the seams of the sod the first year. Control of these grasses is easily accomplished with any number of pre-emergence products on the market. If you would like me to make a positive identification of the weed, please send it to me, in a ziploc bag ( don't add moisture) showing as much of the plant as possible.

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: We have a single plum tree given to us by a friend. It bears lots and lots of fruit, but almost all the fruit splits and falls to the ground before it ripens. Is there anything I can do to keep the fruit from splitting? Is it possible I'm over-watering? The tree gets hit by the lawn sprinklers every day.

A: Unless you live in the Arizona, New Mexico, Texas, or California desert, you don't need to have the lawn sprinklers come on every day, and having any tree watered each day is certainly detrimental to it's well-being. Without knowing anything else about the tree setting, I would say that the watering cycle is what is causing the fruit splits. I suggest you get the sprinklers either re-directed or replaced. An established, fruit-bearing tree should not need any more than a once a week watering at most, and certainly should be able to grow and produce satisfactorily on much less than that. Reprogram the sprinkler controller to reflect the water needs of your turf. Again, unless under the extreme conditions, most cool-season lawn grasses will remain green on 1 inch of water per week, assuming other proper cultural practices like mowing and fertilization. This translates to 640 gallons per 1,000 square feet of turf. I would suggest applying water as fast as your soil can allow it to infiltrate without runoff, making sure to wet the soil/root zone profile completely, doing so just twice a week or possibly three times under severe conditions and a nearly pure sand soil.

Q: How do I clean up my hollyhock bed for next year, specifically quackgrass control and other weeds? (E-mail reference)

A: Quackgrass will need to be treated with Roundup. You can use Treflan or Casoron for other weed control, depending on what they are. Check label for accepted crops before using.

Q: We need some direction in making a flowering plum turn into a tree vs. a bush. It was planted this spring and is now about 3 feet tall. We know it needs to be pruned to help it get into "tree mode." It has lots of new branches, the lower ones having green leaves. Our concern is to when to start pruning, now as the new branches appear or when it's dormant? How should any area cut be covered, putty or tape? (E-mail reference)

A: The best time to prune is during spring dormancy. It is not recommended to cover the pruning cuts with anything. They will compartmentalize and seal themselves much better without any covering.

Q: I want to know what to do with dill in my garden that has aphids in it. Can I still use the dill, and is there something I can do to control them? (Grafton, N.D.)

A: Aphids and dill go together like peanut butter and jelly. In fact, dill is often used as a trap crop for aphids and to attract predatory insects like lady beetles to feed on them and protect the rest of the garden. You can use organics like Neem or pyrethrum to control them with no harm for culinary purposes.

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: 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.

Do you have a gardening or houseplant question? Write to Hortiscope, Box 5051, NDSU Extension Service, Fargo, ND 58105 or e-mail to Ron Smith at ronsmith@ndsuext.nodak.edu. Note to e-mail correspondents: please identify your location (city and state) for most accurate recommendations.

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Source: Ron Smith, (701) 231-8161, ronsmith@ndsuext.nodak.edu
Editor: Gary Moran, (701) 231-7865, gmoran@ndsuext.nodak.edu