Questions on: Geranium

Ron Smith, Horticulturist, NDSU Extension Service


Q: The geraniums we dug up (pot and all) and set in the garage window are starting to bloom without getting leggy. Also, my philodendron that is in a southeast bay window is losing leaves off and on. The leaves that are falling off are closest to the pot. The whole leaf will turn yellow and drop off, but it keeps growing new ones on the ends. It is fastened to a wall close to the ceiling and has been in the same pot for close to five years. I measured 86 inches of vine flowing in both directions from the pot. Parts of the vine contain larger leaves than others. I talked to a lady who has a private greenhouse who says she has the same problem, but hasn't found a cure. Can you please help us out? (e-mail reference)

A: You obviously don't need any advice on your geraniums because it sounds like they are doing just fine! For the ivy philodendron, have you ever heard of pruning? I know you have. If you want something approaching normal foliage, you need to prune from time to time. It is perfectly normal for the old leaves to drop off. It's much like us losing old hair. The fact that it has been in the same pot for five years has got to be something of a record that Ripley might be interested in hearing about. The different-sized leaves relates back to your fertilizing and watering habits. Any variations would be the probable source of these differences. Take some cuttings from the growing end of the vine and root them in a mix of sand and peat moss. Once you have those established with roots, begin a gradual reduction in the length of the vine. At some point, new growth should emerge that will help improve the aesthetics.


Q: We have two Martha Washington perennial geraniums. Their stem sections are quite hardy (more like shrub stems). I’m wondering if the best way to propagate these plants is by root splitting (as in delphiniums) or whether some other technique should be used. In either case, could you please explain in detail the steps that I should take? Your help in this matter will be hugely appreciated. (e-mail reference)

A: I never have tried root splitting Martha Washington geraniums, but they root quite well from stem cuttings. The size or thickness of the cutting shouldn't negatively impact the success of this method. I encourage you to go to my publication on the Web at http://www.ag.ndsu.edu/pubs/plantsci/landscap/h1257.pdf to read or download the details on stem cutting.


Q: I have geraniums planted in pots, but they look gangly and spindly. Can I trim the plants at this time? How much should I trim so the plants fill in better? (Moorhead, Minn.)

A: Trim the geraniums so there are stubs 3 inches to 4 inches in length. I don't suggest growing them during our dark winter months unless you invest in some good plant lights. I would store them in a dark, cool location. Shake the soil off the roots and dust them with sulfur. Bring the plants out at the end of February and locate them in as sunny a window as possible. Use supplemental lighting if necessary.


Q: My geraniums bloom, but the flowers dry out in the center. Is there something I am doing wrong? (e-mail reference)

A: It sounds like it could be botrytis fungus. The fungus usually is caused overwatering and/or poor air circulation. If you are watering using an overhead method, change the technique and keep the water off the blossoms.


Q: I took my geraniums into the house last fall because they were so beautiful and felt the oxygen created by the plants would be good. I seem to kill every plant I've ever had, so I gave up. I thought the geraniums also would die, but to my surprise they were beautiful all winter. Now they are blooming. Should I cut them back and then water and fertilize when I see new growth? Do I handle them differently because they are blooming? Do I have to replant or can I leave them in the same pots? (e-mail reference)

A: Great news! Just leave them in the same pots unless you want to propagate more geraniums through stem cuttings.


Q: I dug up some geraniums, but left dirt around the roots and left some in pots. Now I'm wondering if I should cut them down even with the dirt and then fertilize. (Marion, N.D.)

A: Trim the geraniums back to about 3- to 4-inch stems and then water. Fertilize when you see new growth emerging.


Q: I have taken cuttings from my geraniums and planted them in the soil using individual pots. I have tried dipping them in Stim Root No.1, but have noticed that quite a few have turned black at the base and died. Can you help? (e-mail reference)

A: Your mistake is the media you have the cuttings stuck in. Get rid of it and plant the geraniums in washed sand, a 50/50 sand/peat moss mix, vermiculite or perlite. The cuttings need moisture and air to root.


Q: My geraniums look healthy, but the leaves are turning a bright red. I am growing them in a greenhouse. This is the second year this has happened. Is the greenhouse too hot during the day? I haven't put up my shade cloth. I am using Miracle-Gro once a week. Any ideas on what I should do? (e-mail reference)

A: This sounds like the problem could be magnesium deficiency, but the only way to determine for sure is through a tissue test. Since I don’t know where you live, try putting up the shade cloth to see if that improves the situation. It also could be from a heavy metal contamination in the water supply, but that wouldn’t be the case if the water is coming from a potable source. These are my best guesses.


Q: Last fall, before freeze, I took in some geraniums in large pots with good soil and put them in a window that faces south. They bloomed well for a time, but not lately. I think they have enough water and fertilizer. Do they like to rest? Should I quit watering for a time? They still have green leaves, though some are dry now and then. (Moorhead, Minn.)

A: The sunlight in our region has been very low until just recently. I suspect the plants are low on carbohydrates because of the flowering. Don't overwater and be patient. As our sunlight intensity and duration increases, the plants will be able to photosynthesize more, store more energy and then bloom again. I am sure they will bloom again before the snow melts!


Q: Please help me with this problem. I started a scarlet border geranium from seed. The veins on the bottom side of the leaves are turning red and the leaves are turning yellow. For now, I pinch them off. What could cause this? (e-mail reference)

A: Nutrient imbalance, too cold of a water or air temperature or keeping the soil too wet could be the problem. Correct whatever it may be and the problem should disappear.


Q: I love growing flowers indoors and out, but I have a problem. The problem is geraniums. I can’t seem to grow them indoors or out. (Alcester, S.D.)

A: I don’t know exactly what to tell you, except the basics. Geraniums need full sun in well-drained soil. Use healthy plant stock and use a starter fertilizer at planting and once a month thereafter.


Q: How short should I cut geranium plants before I plant them outdoors? Also, why would leaves fall off my houseplant? (e-mail reference)

A: Cut the geraniums back to about three inch stubs. They should take off beautifully after being planted outdoors and given a shot of Miracle-Gro. Leaf-drop on houseplants is due to any one or a combination of too low a light intensity, too dry an atmosphere, fluctuations in watering schedules, a cold or hot air draft, insufficient nutrients or watering with cold tap water instead of tepid water.


Q: I believe I have overwatered my geranium because the leaves are turning yellow. Is there any way to save it? (E-mail reference)

A: Stop watering. If it isn't already dead, it should recover. When it dries out again, give it a good watering then wait until the soil is completely dry before watering again.


Q: I brought my fuchsia and geraniums inside because there was a forecast for frost. Subsequently, some very tiny insects that looked like baby flies started flying around the house. Could these be plant related? (E-mail reference)

A: Very likely. They will usually disappear when the central heating is cranked. The dry air dehydrates them.


Q: I would like to keep my geraniums over the winter. Can I put them in the basement? Should I cut them back this fall or wait until spring? How much do I need to water and when? Also, can begonias be kept inside and replanted in the spring? (Edgeley, N.D.)

A: Cut the geraniums back and bring them inside, without the dirt and pots. Keep them in a cool location such as the basement and in a netted bag. Check them monthly for wrinkling. If they are wrinkling, dip them into tepid water for about 10 minutes to rehydrate. In February, repot and place in a sunny window or under grow lights. If your begonia are the fibrous rooted type, they can be brought indoors and grown as potted plants because their demand for light is not as high as geraniums. If the begonias are the tuberous type, you are better off letting them dry down and storing the tubers in a cool location for most of the winter. Repot them in February and give them the same treatment as you would your geraniums.


Q: I have a couple of questions about plant propagation. Do you have to let the cut surface of geraniums dry before rooting a cutting? If you cut the tops off of a pepperomia will it send out new shoots from the bottom? Do you have to let the cuts dry before rooting? I have a goldfish plant that I got as a few sticks in a cup. It is now a very full plant with some of the shoots more than 3 feet long. Four of the shoots, probably the original ones, blossomed this fall. If I cut off the long shoots, can I cut them into sections to re-root or will just the tips grow? (E-mail reference)

A: You don’t have to let the geraniums dry before rooting, although it won't hurt if they do dry but not too long. Pepperomia will send out new shoots only if there is a latent bud there and depending on how much of a stub you leave behind. No need to let the cuts dry before rooting. Your goldfish plant should root if the stem has finished flowering. To help the process, add bottom heat and use a rooting powder.


Q: You were talking about wintering geraniums. I have three large pots that I bring inside, clip the dead flowers and they bloom all winter. I have a plant room with west and south windows and door. I’ve been doing it for three years. My spider plant also blooms all winter and my asparagus fern gets red beads on it. (Fargo, N.D.)

A: I know of many folks who have a set-up just like yours who are equally successful at keeping their geraniums going. For the rest of us, either dry storage or simply starting over next spring is the best bet. Congratulations on your very green thumb!


Q: A lady came into our office seeking information on wintering geraniums. The technique she is looking for involves removing the soil and storing the geraniums upside down. Do you or your readers have any instructions for this method? (Killdeer, N.D.)

A: As far as I know, the method is to cut them back to about 4-inch stems, shake off as much soil as possible, then hang them in a cool, dry location. Repot in February and locate it near a sunny window for growth. During the interim, about once a month, they should be checked to see how they are doing. If they start to mummify, they should be immersed in tepid water to rehydrate them, and then re-hung. You will be the first to know if my readers have any other advice


Q: What is the easiest way to winter a geranium? Last fall, I left one unwatered in a cool basement. When I broke off the dry top in the spring, the stem was still juicy. Given water and a window, it sprouted. Repotted outdoors, it has bloomed prolifically since July 4. Dumb luck, or repeatable? Would the geranium bloom sooner if kept in leaf all winter? Our house temperature is under 65, but window sills and light are limited. ( Moorhead, M.N.)

A: Make of it what you wish, but it is probably a combination of both. Try repeating it again to see if your luck or skill continues. Our winter light is so weak, that unless you are willing to add supplemental lighting, it likely wouldn't bloom any better. Try potting it at the end of February to see if that results in sooner blooming for you. Congratulations on having a green thumb!


Q: What's the best way (if any) to keep geranium baskets through the winter or should I just let them freeze and buy new plants next spring? (LaMoure, N.D.)

A: My opinion: dump them and start new next spring. Life is much easier that way.


Q: Is there a cheap household way to treat flowers that develop fungus? I'm having problems with geraniums and summer phlox. Someone mentioned baking soda, but I don't know how much to add per gallon. I suppose I could buy a well known fungicide and have it for next summer. (E-mail reference)

A: Sorry, but I don't know of a baking soda cure. I would recommend the use of an organic fungicide such as Safer Fungicide and Miticide. Another one on the market containing Neem, another organic, is Schultz Expert Gardener Fungicide 3. It is a miticide, fungicide, and insecticide. All fungicides work better as preventatives than as cures.


Q: We have a grandson who wants to use plants for his science fair. I have two geraniums; one has had natural light and is straggly, the other 16 hours of artificial light and is robust and beautiful. Can you give me some suggestions as to how he can present the plants? Where would we find a light meter? I went on line searching but came up with photography equipment. Any clue as to what we would expect to pay for one? (Gwinner, N.D.)

A: Using a light meter would give some concrete data that he can make reference to, like the robust plant receives 16 hours of light at a footcandle reading of 1000 FC while the spindly plant receives only diffused light, which varies between 50 to 150 FC per day. You can contact Hummert International, located in Earth City, MO. Their phone number is 1-800-325-3055. They have a duo plant light and water meter for about $20. The model number in their 2000 catalog is ID-1830, catalog # 65-6802. While not a "professional" model, it should certainly be enough to provide your grandson with the information and data that he needs for his project.


Q: Is it too late in the spring to start geranium plants from cuttings? Also, could you let me know what the proper procedure is? (New Rockford, N.D.)

A: No, it is not too late to start. It takes about four to six weeks for rooting to take place.

First, select only stems that are healthy. Using a sharp knife, cut them so they are between 4 and 6 inches long. Then, remove the lower leaves and insert the cut end into a sterile or pasteurized medium such as sand, peat moss, vermiculite or perlite. Keep the cutting in bright, indirect light and keep the medium moist, but not soggy. In four to six weeks, roots should be developed! When lifting the rooted cuttings, do so with both hands--one underneath, lifting up, the other gently tugging, being careful to not break any roots.


Q. I have a geranium that has been in the house for two years now. The problem is it does not bloom, even though I have cut it back and repotted it. Could you please give me some advice on how to get it to bloom again? It does get plenty of sunlight. (e-mail)

A. I'll bet it doesn't! Get plenty of sunlight, that is. Geraniums are sun lovers! Bright, direct light is what they need, and plenty of it to bloom, especially the Martha Washington types. Try summering it outdoors and see what happens.


Q. What causes a geranium not to bloom? (Carson, N.D., e-mail)

A. Most likely you're referring to a Martha Washington (I wonder how long before they will name a geranium after Martha Stewart?), which are noted for their difficulty to rebloom.

First they need a summer rest period of about six to eight weeks, where the plant is watered only enough to keep the soil from going completely dry. At the end of that period, knock them out of their pots, cut them back and repot with a quality potting soil mixture. You can use the same pot or a new one. Then increase watering to where the potting soil is moistened throughout with each watering, and allow the top half-inch of soil to dry before watering again.

These geraniums need direct light—no less than four hours a day, and summer them outdoors in a sunny location.


Q. Can you tell me how to dry geraniums? (Garrison, N.D.)

A. Knock off excess soil and store in coolest part of basement. When it appears to be dehydrated, immerse in tepid water for an hour and rehang. Repeat process through winter until February and then repot.


Q. Enclosed are some leaves from a Martha Washington geranium. At first a few rusty spots appear; the whole leaf turns this rusty color and drops off. The blossoms are not affected. The plants were outside during the summer with no improvement.  I started some new plants with cuttings and the same thing happened to them. Other types of geraniums seem to be immune.  Your comments will be appreciated. I read your column with much interest. Thank you. (Jamestown, N.D.)

A. Your geranium samples had the classic symptoms of bacterial leaf spot, including the dropping of the leaves, as described in your letter.  Unfortunately, this is one of those terminal diseases on a plant. It was likely picked up when it was summered outdoors and could have come from splashing water or insect feeding activity.  Control measures call for sanitation of pots, cutting knives and soil. Diseased plants in the greenhouse business are dumped.  Sorry I can't give you good news. Thank you for being a faithful reader of the column.


Q. Enjoy reading your column in the Farm Forum. I have two questions for you.

No. 1: Is there a good way to "winter over" the geraniums to save them and make them bloom again next spring? I have been told to put them in a basement, but then what? Do I trim greenery down and how often do I water and how much light?

No. 2: I received a beautiful red gloxinia for Mother's Day. After the flowers fell off, the plant has become almost like a vine. How can I make it rebloom, or is it a one time bloomer? (Tyler, Minn.)

A. You ask for a "good way" to overwinter geraniums. Well, the best way is in a heated greenhouse with supplemental lighting and deionized or reverse osmosis water. Since that is not likely possible, here is the next best thing.

Place them in the basement and cut back to about 6 inches in length. Shake as much soil off the roots as possible. check them every two weeks and if they begin to shrivel, immerse in tepid water to rehydrate. Then, along about Feb. 1, pot them up and place in a sunny window. By the time the last killing frost passes, you can set out blooming geraniums. Gloxinias are members of a group of plants known as gesneriads, which include African violets. These need strong, bright light, but not direct sunlight. After flowering, allow them to dry down until the leaves turn yellow and dry up completely.

Store the plant in a cool, dry location for the winter and repot using fresh, pasteurized compost in the spring. Keep warm (70+ F) until the tuber starts producing new leaves, then resume regular watering, normal light and fertilizer practices for a nice summer of blooms.

Thank you for writing!


Q: Could you tell me if perennial geranium (Cranesbill) will flower all summer and, if so, do I need to deadhead it? (e-mail)

A: The cranesbill geranium will flower a couple of times during the summer but not all summer. No perennials I know of do that: they all have periods of bloom--spring, summer or fall--and in some cases like the perennial geranium, spring and late summer. No deadheading is needed, although what I did once by mistake was to mow one down after it was flowering, and it came back a better plant and flowered beautifully.


Q: Can I winter my ivy geranium? It has been outside and I potted it. I only have a north and west window for sun. (E-mail reference)

A: Yes, you can winter your geranium indoors as a potted plant. Use the west window and provide supplemental lighting if possible, with a Gro-Lux bulb. Set it back a little from the window to cut down on a direct cold draft coming from it in the winter.


Q: This fall, a friend gave me her geraniums before they froze. I cut off the tops and planted them in 4-inch pots. I have them under fluorescent bulbs and am amazed how fast they have grown. Some are about ready to bloom. So they won't get leggy before next spring, should I cut them back again, or keep pinching off the new growth? I realize this is a long time to wait, but I have the room for now, and would love to have them in great bloom in the spring. (E-mail reference)

A: I suggest cutting them back as they get too tall. Also, keep the flowers deadheaded. As they complete blooming, remove them so they don't set seed. You might even try taking cuttings on the longer growth to see how many you can propagate before planting time next spring!


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