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Ron Smith answers questions about flowers, trees, gardens and shrubs.

By Ron Smith, Horticulturist

NDSU Extension Service

Q: I am wondering about planting a flower garden of biennials (hollyhocks) and perennials by my garage. They would be planted near an established engleman ivy. I will be lifting turf to do this. How far away should I plant to lessen the impact of competition for water resources on the ivy? Would 2 to 3 feet be acceptable? The plants will be facing west. (Jamestown, N.D.)

A: That distance should be more than adequate for these herbaceous plants to grow. The ivy has a very extensive root system, so when you come to the roots, try to make clean cuts with a sharp spade or hand pruner to facilitate faster healing.

Q: I am trying to get some information on growing iris plants in the shade. Can you help me, please? I have no sunny place to plant my Dutch iris bulbs. I do have a spot that gets a few hours of sun at the end of the day. Will my irises grow in this spot? (e-mail reference)

A: They will grow, but not flower as robustly as those that get full exposure to the sun. Don't give them too much fertilizer. In fact, none should be needed at all unless the soil is very poor. If it is dappled shade during the day, that will be fine. It will supplement the direct but weaker sunlight they will get toward the day's end.

Q: I need some serious help with my dieffenbachia. I have had this plant for about three years. The plant had one cane with two stalks growing out of it. About three months ago, the stalks started splitting and getting soggy and mushy. I took the cane out of the dirt and found the root where the stalks connect was rotten. I looked very close to see why it was rotting and saw these tiny, mite-looking bugs eating away at the root. I cut away the root and bugs, dipped the canes in alcohol and put them in water to root. Within a few days, I could see a root growing out from the cane. I planted one of the canes in some new soil once I thought enough root had grown. I left the other cane in the water. Just a few days ago, the cane I planted fell over. It was soggy and mushy at the root. I looked at the one in the water and found all but 2 inches from the leaves also is soggy and mushy. What should I do? (e-mail reference)

A: If there is anything left that is solid on either of these canes, cut them back to healthy tissue and lay them sideways in a flat of damp, unmilled sphagnum moss. Barely cover them with the moss and keep them in a well-lit room. In a few weeks, new leaves should emerge from the top end of the stem and roots should start to show up at the base end. This stalk should be about 4 inches long but no longer than 6 inches.

Q: My tenant, not knowing it was a young oak tree, cut it down to about 6 feet tall. The tenant thought it would leaf out at the cut site. I’m very upset. Will this tree survive and sprout from the cut point? Is there anything I can do? (e-mail reference)

A: Unfortunately, there is nothing you can do. Even if it did sprout, it wouldn't last long and it wouldn't be something you want to be looking at anyway. It would never fulfill the functional or aesthetic character it was intended for. It’s amazing to me that your tenant did not realize he or she was trimming a tree instead of a shrub. Take the pruning saw away from your tenant!

Q: This is my first experience with an amaryllis, but it is going well so far. My sister-in-law received the kit in December of 2008 but never took it out of the box. She gave it to me after it sat in the box for about three weeks. I followed the directions on the box and had two stems with three flowers each this past December. The leaves are growing well on the main bulb, plus there are four offsets. Do I need to separate the offsets from the main bulb? If so, when should I do it? (e-mail reference)

A: It would be a good idea to remove the offsets and plant them separately. Eventually, they will get to a size sufficient to get them to produce flowers for you. Once the bulb has stopped flowering, the offsets can be removed at any time.

Q: I bought two ficus trees a couple of months ago. One is inside the house, while the other is outside. Both seem to be doing well. However, I just noticed the inside plant has what looks like white powder between the leaves where there is new growth. What is this? (e-mail reference)

A: Lift some of it off with a cotton swab if possible. It usually is an insect known as cottony cushion scale or spittle bug. If you only have a few of these showing up, removing them in this fashion will suffice. If there is a heavy infestation and it proves to be an insect, a systemic insecticide containing the active ingredient imidacloprid should be used. Be sure to follow the directions on the label.

Q: We have several crepe myrtles that we may not prune this year. Would not pruning cause problems? If not, do we need to at least cut off last year’s berries? (e-mail reference)

A: No need to cut off last year’s fruits because they will disappear eventually. Pruning crepe myrtles is something that rarely should be done. However, you should remove the spent blooms from the first flush of flowers to get a reblooming again later in the summer or fall.

Q: We have two rows of arborvitaes at both ends of our tennis court. The winter snow caused several of the branches to bend outward. What is the best way to support these branches so they grow up instead of out? (e-mail reference)

A: Some light pruning and patience. Unless there was some structural damage, the branches will go back to normal this spring. If they don't straighten up with the arrival of warm weather, then woody tissue damage was done and the likelihood of returning to the original position is reduced. You might try tying stakes to them to get them going straight and heal.

Q: I have a dancing dolphin vine houseplant, but I would like to have more of them in my pot. Do I just cut a piece off and stick it in water? (e-mail reference)

A: Simply cutting off the stems will thicken the plant. Sticking some cuttings in water should root them as well, but I'd suggest using perlite or vermiculite as the rooting media.

Q: I have about 20 peony plants because they are my favorite flower. However, two of my Sarah Bernhardt varieties were not getting enough sun because of another plant that was crowding them. I dug them up to move them and accidently snapped the big root/bulb into two pieces! Is this going to kill the plants or will they bounce back? Irises seem to bounce back from this, but I've never moved peonies before. (St. Louis, Mo.)

A: They should bounce back if there were any buds in the parts that separated.

Q: I have a couple of questions about my spider plant. My house has no east or west windows, so what should I do besides putting it outside during the summer? All of the leaves have brown tips, so I have been pinching the ends off. Should I be doing this or just letting it go? (Vancouver, Wash.)

A: Any window placement is better than none. I have one placed in a north window and it is doing just fine. Summering them outdoors does wonders for them. I'd also suggest leaving the foliage and the brown tips alone. It doesn’t do any good pinching or snipping them back. If an entire leaf dies, just pull it off. An alternative to the ideal window placement is a plant light. However, that may not be practical on hanging spider plants. These are tough plants that have the ability to endure quite a bit of intended and benign neglect.

Q: We live in northwestern Florida and have three hibiscus plants that we keep outside in pots. We do not bring them in for the winter. This winter, we had several hard freezes and the plants look dead. The plants do not have leaves, and when you break off a limb, there is no green on the inside. Are these a lost cause or should they be cut back to see if they revive? (e-mail reference)

A: They might be a lost cause, but it depends on how cold it got and for how long. I'd suggest cutting them back because you have nothing to lose except a little time. If they come back, you've come out on top. If not, you can start new plants this spring.

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

NDSU Agriculture Communication

Source:Ron Smith, (701) 231-8161,
Editor:Rich Mattern, (701) 231-6136,
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