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Hortiscope

Ron Smith answers questions about plants, trees and gardens.

By Ron Smith, Horticulturist

NDSU Extension Service

Q: I wonder if you could help answer a question about how someone cut my trees. My 25-year-old crepe myrtles were 30 feet tall. I wanted the trees cut back to about 15 feet and correctly pruned. The trees were top-heavy during full bloom and didn't do well during some of the intense Texas storms we get. Unfortunately, the people who cut the trees chopped them off in a straight line at 10 feet. There are a couple of trees that are just stumps. Will my trees survive given their age and the severity of the pruning? Is this as bad as I think it might be? (e-mail reference)

A: It probably is as bad as you think. The deadheading of any shrub or tree is a bad idea, especially crepe myrtles. Let this be a lesson to you and anyone else who reads this column. Before you turn someone loose on your trees and plant material, check his or her credentials, professional association memberships, formal education in the science and art of proper pruning, and get some local references. If you are lucky, what will happen this spring is that some growth will come from the crown. If you are very lucky, the growth will not be spindly and gradually will mature into nicely developed canes that can support flowers. If this happens, I suggest playing the lottery in your state! What they should have done is remove the oldest wood back to the crown during a three-year period. This would encourage new growth to be generated from the crown and thinning the basal shoots to keep the crown open to express the attractive bark this species shows as it matures. It wouldn't have given you the instant effect that you now have and the resulting hedge planting through the years would have been attractive. See what develops this spring as new growth begins. If sucker growth springs up all over, you might just go ahead and remove the plants. If the new growth is more reserved and with healthy, firm canes, then cut the ugly stumps back and try to nurture the plants to where you want them.

Q: I was wondering if it would be a bad idea to plant grass in the same pot as my jade plant. I think it would look cool, but not if the plant in the middle of the grass is dead. (e-mail reference)

A: I have nothing that would say it shouldn't or couldn’t be done. I can't think of anything from the grass that would hurt the jade plant, unless it becomes overgrown and chokes out the plant.

Q: I live on the line between zones 7 and 8. I have a yard with sandy soil that is adjacent to a tree-covered lot. I'm thinking about purchasing some American arborvitae trees from the Arbor Day Foundation. The trees will get plenty of sun because the trees in the adjacent lot will be north of my trees. Do you think American arborvitae will grow well in these conditions? I'd like to allow them to grow naturally to create a nice border. How far apart should I plant them? (Raleigh, N.C.)

A: The seedlings from the Arbor Day Foundation would be a small investment to make. I am sure you would experience some success. Your biggest enemy probably would be deer and rabbits, but not necessarily in that order. I suggest planting them about 3 feet apart. This is too close for continuous growth as they take hold and mature. However, after five or six years and before they start touching each other, you could thin out ever other plant if you desire. They will not be very vigorous growers in your borderline zone area. However, with your microclimate and some good management on your part, you would get the arborvitae established. I encourage you to try it.

Q: I planted 13 Norway spruce trees in a straight line. I planted a tree every 15 feet. Did I plant them too close to each other? My grandpa planted Norway spruce trees the same way back in 1978. These trees are about 60 feet tall. Will they still be around in a 100 years? I’m ripping out box elder trees to replace them with evergreens. I think it’s a good idea because everyone tells me box elder trees are junk. (e-mail reference)

A: Box elder trees are not considered junk, but also aren’t highly desired by most people. However, they do serve a purpose in many settings and will continue to be used. I have to admit that I've seen some good looking ones. Your spacing distance is good for planting Norway spruce. I did the same thing for my parents 40 years ago. The trees are large, magnificent and form a nice screen between property lines. If the trees will be around 100 years from now is something that no one can guarantee because there are too many variables to consider. Who knows, they might not survive a year! However, statistics show the trees will live a long time, but it depends on exposure, climate conditions, pesticide use, and insect and disease activity.

Q: I just stumbled upon your Hortiscope Web site looking for information on Bali cherries. I read about a person from Fargo who had North Star cherries that weren’t producing well and he wanted some Bali cherries. St. Lawrence Nurseries has Bali cherries, but they are too spendy for me. The nursery’s Web site is at http://www.sln.potsdam.ny.us/. I have a small fruit and produce garden about 45 miles from Fargo. This is the third year I’ve been open to the public, so I still need more of everything, but I have some cherry trees to spare. I think they are North Star. I got them from my mother about 10 years ago. I also would like to find Bali cherries, but at a more reasonable price. I have royalty raspberries I could swap plant for plant. I would like to find someone who has Caroline or red mammoth. Let me know if you know of someone who would like to do some plant trading. I think your knowledge could help me a lot. People can contact me at The Garden on Highway 35, 29507 Lazy Loop, Underwood, Minn. 56586. (e-mail reference)

A: I'll be glad to help you in any way that I can. After your note reaches the papers and the Internet, I'm sure someone will be responding to your request.

Q: Could you tell me how to get a stem to root? From what I understand, I need to cut off the end of a tendril of my dolphin plant and dip it into a root hormone. However, then what? Do I place the stem in a glass of water or place the dipped root into the same soil as the plant? I also read that bottom heat is good. What is bottom heat? Mine just finished flowering and I would like to root some slips for friends. (e-mail reference)

A: Once you have dipped the cut end into the rooting hormone, you want to stick it into a mixture of sphagnum peat moss and clean sand or either one. However, sphagnum peat moss is the preferred choice. The peat should be soaked and wrung out as much as possible before sticking the cutting into it. This will provide the proper dampness and air mixture that is needed for rooting to take place. Bottom heat is obtained from a garden heating pad that maintains a constant temperature. These can be purchased from local garden centers or one of the big-box stores. It makes a very pronounced difference in rooting success. However, it causes the peat to dry more quickly, so you need to monitor the peat to be sure it stays moist. Mist with distilled water until the rooting is complete.

Q: We have a severe water shortage, so I want to look at the best use of the water that I have available. I’m wondering if I can water my plants with the leftover coffee. I make a full pot of coffee each morning, but we sometimes do not drink the whole pot, so throw the remaining coffee down the drain. By the time I get home at night, the coffee is cold, so this is when I would want to use it on my plants. (Sonoma County, Calif.)

A: Coffee is "improved water" as far as a house or outdoor plant is concerned! I do it all the time with the houseplants in the office and at home. We (actually my wife) take the leftover coffee grounds and mix it into the soil of our Square Foot vegetable garden. So far, we haven't seen any plants suffering from caffeine jitters! The coffee we drink in the office has a pH of 5.6, which is quite acidic. When poured into the soil, the coffee will depress that pH temporarily without harming the plants. In fact, such a temporary drop tends to make trace elements, such as iron and copper, more readily available. For those who want to attempt growing blueberries in a high-pH soil, try mixing the used coffee grounds in to depress the pH more permanently to achieve the level needed for good blueberry production.

Q: I purchased three crotons (banana, petra and mammy), but I didn't realize how difficult they would be. My petra and banana are doing fine, but the leaves on the mammy are getting soft and wilting. What is the problem? (e-mail reference)

A: I can't say for certain with the information provided. It could be due to overwatering, poor draining soil, nondraining container, bacterial disease or root rot. Generally, these are some of the most problem-free houseplants on the planet. Crotons even stand up to benign and willful neglect. The overall wilting that you describe does not bode well for the plant, so I would suggest dumping it.

Q: I enjoyed reading all of your advice about lily care on your Web site. I planted two species of calla lily (white and spotted yellow) in a flowerbed outdoors. I should tell you I live in south Florida. How do I cut or remove the spent flowers once they start to turn brown and die? There seems to be new shoots growing right behind the dying ones. Also, the yellow calla lily doesn’t blossom as wide as the white one and seems to have some type of pods growing in the blooms. What are they and can they be planted? (e-mail reference)

A: Great to hear from you in south Florida! I don't even want to think about the temperature down there because it is cold here. Keep in mind that the native environments for calla lilies are swampy regions in South Africa that have wet/dry cycles. The dry cycle occurs during the summer months. Attempting to keep the plants going throughout the year in your environment is going to lead to frustration. The lilies will attempt to shut down after their blooming period. You will see a gradual fading and yellowing of the foliage. The foliage can be removed once senescence is complete. Also, they thrive best with early morning sunlight and shade during the hot afternoons. What you are referring to as the flower actually is known as a white spathe or leaf surrounding the spadix, which is a spike that contains many small flowers. I don’t know if the plants will produce viable seed. I've never heard of them doing so. All the calla lilies I have seen were asexually reproduced. If calla cannot grow in its native environment, we Americans are better off keeping them in containers where we can control the water availability much better. Also, the yellow calla lily has a reputation, for some reason, as being the more challenging one to grow.

To contact Ron Smith for answers to your questions, write to Ron Smith, NDSU Department of Plant Sciences, Dept. 7670, Box 6050, Fargo, ND 58108-6050 or e-mail ronald.smith@ndsu.edu.


NDSU Agriculture Communication

Source:Ron Smith, (701) 231-8161, ronald.smith@ndsu.edu
Editor:Rich Mattern, (701) 231-6136, richard.mattern@ndsu.edu
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