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Hortiscope

Ron Smith answers reader's questions about the world of plants and gardening.

By Ronald C. Smith, Horticulturist

NDSU Extension Service

Q: I planted a few hollyhocks two summers ago. They bloomed and flowered beautifully, but now I have tons of plants showing up. Last year I left them alone, but they never produced flowers. I eventually tore them out. I don't know if I bought biennial or perennial plants. I really love them and want them to reproduce, but with no flowers, the plants look like weeds. I love lilacs and have a few of them in my garden. Are lilacs a type of the plant that if I cut off the flowers they will keep blooming? (e-mail reference)

A: I wouldn't rip out all the hollyhocks. Keep just enough plants to keep your garden from looking weedy. You may have biennial hollyhocks that require another cold period before they will flower. Lilacs will flower every year if you harvest the flowers. The flower buds are set for the following year on the subsequent growth that takes place after they flower. If you prune the plants late in the summer, you will remove the flower buds for the following year.

Q: I recently purchased an Aphelandra squarrosa from a local plant shop. Unfortunately, it has a lot of aphids and the bottom leaves are turning brown, shriveling up and dropping off. I'm trying to decide the best route to deal with the issue. There are some factors to take into consideration. I'm in a dorm room and have nowhere to put the plant for treatment, so the treatment has to be something that can be done inside. I'm leaving in a couple of months, so I will be giving away the plant to my roommate. I do not want to give her a problem plant that she has to hassle with. With that in mind, would it be better to try to treat it or just chuck it? What treatments are possible? (e-mail reference)

A: I'm half tempted to tell you to take the plant back to the shop that sold it to you, but you probably couldn't get away with it anyway. The best treatment for aphids under your conditions is to use an insecticidal soap. You need to make direct contact with the aphids for the material to work. You likely will have to do at least a couple of applications to bring the aphids under control. Aphids are a group of 4,400 species of small insects that feed on the phloem fluid of plants. Aphids reach a large population size very quickly. These reproductive characteristics allow aphids to quickly colonize, especially on indoor plants where there are no checks and balances from nature. If you are up to the battle, arm yourself with some insecticidal soap and begin attacking. This material kills by disrupting the structure and permeability of the cell membranes. In other words, the aphids will dehydrate or suffocate. Insecticidal soaps are the safest approach to controlling these and other soft-bodied insects because they do not contain organic solvents and have no residual affect. If you are not up to doing battle with this stubborn, stupid and prolific insect, then dump the plant!

Q: I have always loved phlox. I found some bulbs after I bought my own home. When are they supposed to be planted? (e-mail reference)

A: You inquiry doesn't make sense to me. Phlox are herbaceous perennials, not bulbs. If you have bulbs and don't know what kind they are, I can't advise you accurately. Some bulbs, such as tulips and daffodils, are winter-hardy. Other bulbs, such as tuberous begonias, are not cold-hardy at all. The hardy bulbs are planted in the early fall, while the others are planted after the danger of frost is past.

Q: I have operated a bed and breakfast in Asheville, N.C., for almost three years. The home on the property was built in 1885. We think that the grapevine is probably more than 100 years old. There is a root/vine that is running on top of the ground. Every foot or so, a few roots have grown out of the root/vine and are anchored into the ground. Do we somehow need to guide this root onto another training system or do we prune the root back? (e-mail reference)

A: The grapevine is exhibiting a talent for serpentine layering. Roots form at nodes that come into contact with the soil. These can be separated from the mother plant and grown as a stand-alone grapevine. You might have a special grapevine, so I would suggest contacting a horticulturist at North Carolina State to see if someone is interested in grand, old plants such as this. Something that has survived and produced this long may be a launcher of some tough, new grapevines for commercial production that may be of value to the wine industry.

Q: The town we live in is graciously giving away trees. Our choices are hackberry, oak, maple, linden, pear, hornbeam or London plain. The trees must be planted on the front lawn. We have a pin oak on our front lawn, but realize it will take some time for this type of tree to mature. Last year it had less than two dozen leaves. We are considering a hackberry because we heard it is quick-growing and drought-tolerant. How long does it take a hackberry to provide shade? Should we consider planting it and then removing it in 10 or so years after our pin oak matures? Should we let both trees grow or forget about planting the hackberry? (e-mail reference)

A: I would stick with oak trees, even if the oak trees being given away are not pin oaks. I'm not in favor of moving trees in the landscape once they have been planted unless it is absolutely necessary. The rate of growth is about the same for all of the species you are being offered.

Q: A friend of mine has a ficus tree he inherited from a neighbor. The leaves are falling and dying in places. I looked at the tree and found a waxy-type substance, almost like white candle wax, at the base of the leaves. Some of the leaves are drying at the tips. I was thinking it was some sort of infestation. Is this correct? Will fungicide soap help? I am a master gardener volunteer in Wisconsin, so he thinks I know everything! (e-mail reference)

A: Glad to help! Your waxy substance at the base of the leaves probably is some kind of mealybug. I'm going to suggest that you go to one of the references I have on my Web site that should help you bring into focus exactly what it is. The information is available at http://www.ag.ndsu.edu/pubs/plantsci/landscap/pp744w.htm. If you scroll down to where insect problems are discussed, you will find mealybug infestations described. While Malathion would work, it has a very strong smell to it that would drive everybody out of the house. I would suggest that you attempt to control the insects with an insecticidal soap or a systemic that is labeled for houseplants. If the infestation is too high, your friend probably would be better off dumping the plant.

Q: We have purchased an old home that has two maple trees that hang over our back deck, porch, shop and patio grill area. I really don't mind the natural things that fall from a tree, but the birds that have been feeding on the buds and blossoms have left a little too much to clean up. My child shouldn't be playing in it, either. I never have heard of birds feeding on the buds and blossoms of such a large tree, but I don't know much about it. Is there anything that would discourage the birds? These trees are fabulous shade for the back area, but not if we can't go out and enjoy it. (e-mail reference)

A: I am not a bird specialist, but from what little I know, birds have habits just like humans. There is no simple solution. You cannot legally shoot, trap or poison them. I would suggest contacting the Fish and Wildlife folks in your region of the country. Go to http://www.fws.gov/offices/statelinks.html to get the locations of the offices in your state. Usually, extreme scare tactics will move them away, but the experts will have some specific guidelines for you. Just don't cut down the trees! This problem can be solved.

Q: After looking at a number of nurseries, I've found none that have techny in stock. They all say that they can get them, but I'd prefer to see what I'm getting before I buy. It seems that there are lots of emeralds available. One nursery had a bunch of them available at what looked to be a reasonable price. Do you have any problem with emeralds? Emeralds have less spread, so I probably would have to buy more of them. (Pittsburgh, Pa.)

A: Go for the emeralds because there is no point in ordering something else when these beauties are available. Send some to me! Ask when they were dug from the nursery because I'm curious.

Q: I noticed that two of my spider plants, which are across the room from each other, have holes in the leaves. It looks as if someone was munching on them. There is dirt all over the leaves as well. I have more than 20 house plants in my home and love them all. I really don't want to lose these spider plants. I call one of the plants "big momma." This plant has given me about five healthy, new spider plants. I live in southwest Florida. (e-mail reference)

A: You didn't say if you have cats. Our cats put holes in our spider plants whenever they get the chance! I certainly cannot tell you who is eating holes in your plants, but whatever it is probably comes out at night and enjoys a bite or two. I would suggest that you take the plants outside on a warm day and repot them in fresh, pasteurized potting soil.

Q: I bought quite a few flats of petunias. I planted, watered and fertilized the plants, but now I've noticed that the flowers have white spots. What are the spots and how do I get rid of them? (e-mail reference)

A: These could be some fertilizer burns that are not harmful to the plants. Future flowers won't have these spots. When you fertilize, be sure the material is totally water soluble. If you do use a dry fertilizer, be sure to water it in completely and keep the fertilizer off the foliage and flowers.

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: I have propagated some seeds from a flowering amaryllis. Two of the seeds rooted and formed leaves, but have died back. This is their second year and one of them has formed more leaves than last year. I am not sure if and when they will flower, but I am prepared to wait. Is there anything I can do to encourage them? I haven’t changed the compost or the size of the pots because I am not sure if that is the right thing to do. (e-mail reference)

A: Let them stay where they are. When warm weather settles in, set them outside on an eastern or northern exposure close to the house. Allow them to dry down this fall. More directions are available at http://www.ag.ndsu.edu/pubs/plantsci/landscap/h811w.htm.

Q: I am trying to find out if anyone has used the sap from a Manitoba maple to make syrup. Is the sap from this tree toxic? (e-mail reference)

A: You can make syrup and it is not toxic.

Q: I have a jade plant that has a hard, brown layering on top of the leaf and wraps slightly around the bottom of the leaf closest to the stem. The layering has about the same texture as the jade bark/stem. It started in late fall and seems to affect the new leaves at the top of the plant, but the rest of the plant is infested as well. Can you tell me what it is and how to treat it? (e-mail reference)

A: Scale insects are difficult to control. There are several remedies that can be tried in an attempt to eliminate scales from a houseplant. However, there is no easy, simple cure. One possibility is to pick off individual scales or gently scrub (or rub) the scales loose from the leaves and stems. This is a labor-intensive task that only works on small, large-leafed plants. Dabbing each scale with an alcohol-soaked cotton swab is another possibility on lightly infested plants. Insecticidal sprays have limited utility. Their effectiveness is related to how well the material is applied and the duration of the particular insecticide. Try an insecticidal soap to see if that works.

Q: I woke up this morning and found that there were little, leaking holes (almost uniform) around my maple tree about 3 feet up from the ground. I've never seen this before. Can you tell me what might have happened last night? (e-mail reference)

A: You have sapsucker activity on your tree. They ring trees with their pecking. When the sap begins to flow through the phloem tissue just below the bark, it causes bleeding. There is nothing to worry about. This is a temporary phenomenon that occurs in the spring from root pressure that will end as the leaves open. Too bad you can't tap it for syrup! Thanks for the excellent photo. I'll use it in my classes!

Q: After several weeks of warm weather, a severe cold snap descended across Michigan. I planted 1,000 tulip, alium, daffodil and hyacinth bulbs last fall. All of them were emerging when the cold snap hit. My sprouting bulbs, especially the well-developed tulips closest to the home, are now wilting in the snow. Have I lost these tulips? Is there anything I can do to save the season? After a week of severe frost unlike anything I've seen in April before, I can't imagine a vibrant spring garden. (e-mail reference)

A: If it is any comfort, we suffered through the same weather as you! Normally, established tulips will tolerate reverses in weather, but apparently yours are long gone. If you purchased your bulbs locally, they should be able to tolerate reasonable swings in spring temperatures, but I think we can agree that the weather this spring has been anything but reasonable!


NDSU Agriculture Communication

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