March 25, 2004

Hortiscope

Ronald C. Smith, Horticulturist
NDSU Extension Service

Q: What fungicide do you suggest for rhizosphaera needle cast? What are some appropriate suggestions on application, timing, etc? (Linton, N.D.)

A: Rhizosphaera needle cast, assuming the plant isn't too far gone, is best controlled with a product known as Bravo, which can be applied during the late spring or early summer months. Follow the directions on the label. It will probably have to be applied for two or three years in a row to bring it under complete control.

Q: I have a row of arborvitae on my property line that is now as tall as the power line above. Should the tops be trimmed? Will it improve the growth below? Growth on the bottom has been dying as the trees have aged. Is it because of the height of the trees or a natural occurrence? If there is no way to bring this growth back, would it be harmful if I heaped up the lower area with mulch and wood chips? What is the best fertilizer for these plants? (E-mail reference)

A: The thinning out is a natural process of this species. Under cultivation, they usually top out at about 30 feet. In their native environment, they top out at 50 to 60 feet. The tops can be trimmed which often results in better growth below, depending on how close together they are planted. More thinning occurs if they are planted close together. If you bury the roots in mulch, you will very likely kill the trees by cutting off the air supply. It may also cause them to re-orient their roots upward into the mulch, which reduces the stability of the plant. These trees seldom need fertilization. If you think they do, an annual application of Miracle-Gro when new growth is just beginning will suffice.

Q: My jade is 25 to 30 years old. The main stalk is four to six inches in diameter and still strong. I keep it in a 7-gallon container. One by one, over the last year, many of the larger branches have shriveled and wilted. They eventually separate from the stalk and drop to the ground. Branches are also falling off. There are now eight or nine large nodes on the stalk and sub-stalks where these larger branches have fallen off. I water it infrequently because the soil seems to retain a lot of moisture for a long time. It is planted in a succulent top soil mix. The bottom of the planter has three to four inches of medium stones for drainage. It has not been exposed to much light but I have recently rectified this problem. Should I replant it in a more specific soil? How much water should I give it and when? I have been giving it small amounts of a succulent fertilizer mixed with water. (E-mail reference)

A: Repot and eliminate the stones in the base of the planter. The stones are causing at least part of the problem. For good drainage, the container media needs to be uniform with no layering of stones. Simply put a screen over the drainage hole on the bottom. Keep the plant in strong light and water when the soil is dry. Fertilize only when new growth is evident. Take leaf or stem cuttings and root them in case this plant doesn’t survive.

Q: I have two old lilac bushes that need to be removed. How do I remove them without getting a ton of shoots coming up? How large do the roots get? (E-mail reference)

A: Accept the fact that you will not be able to remove all of the roots and that you will have suckers popping up all over. Treat them as weeds by spraying with a typical broadleaf herbicide. You will probably have to spray two or three times over the summer. Depending on how old they are, the roots can get as big as a person's leg.

Q: What varieties of asparagus would grow best in North Dakota and can you suggest a source? You have said a hungry deer will eat almost anything. Will they eat asparagus? Will hail in late summer harm the crowns? (E-mail reference)

A: I don't see why deer would ever pass up asparagus since we humans find it so tasty. Hail damage may occur, depending on the hail size and intensity. The crown is buried beyond direct contact, but if the fern is extensively shredded, it will not make enough food for next season's growth to be adequate. Viking, Mary Washington, and Jersey Giant are good varieties. Just about any seed catalog that you receive in the mail should have these varieties.

Q: I was given a heart shaped hoya leaf rooted in coconut husk. Could you tell me the proper name of this variety? Will it grow to become a plant or just stay a leaf? I have heard many conflicting answers. (E-mail reference)

A: I think the one you are referring to is known as hoya australis. If it is rooted, has sufficient bright light and other growth factors, it should grow into a climbing/trailing vine like the others.

Q: I have an indoor chenille plant that I love. Lately it hasn’t been doing well. I've just finished looking for information about the plant but there seems to be slight variations on how to care for it. I have the plant right next to a west-facing window (I don't have a south-facing window). I wonder if the plant has been too close to the cold of the window. I spray it with water three or more times daily and water it the first day the soil is dry. I have been fertilizing it about once a month. It's losing leaves daily. The leaves turn yellow and dry up and fall off. Today I cut the plant back and took off all of the flowers and am starting fresh. I have to admit that about three months ago I sprayed it with hairspray because I thought it was my water bottle. I immediately sprayed it with water and gently tried to wash it away with my fingers, but you could tell there were still deposits on the leaves. The plant seemed fine for quite a while but suddenly the leaves started turning yellow and falling off. I don't know if that mistake is causing my problems. Also, what is the proper way to propagate its clippings? They are in water right now. (E-mail reference)

A: You are setting too high a standard for yourself. The picture you sent of a chenille plant is of a perfect plant. Just like gorgeous male and female models we see with perfect skin, hair, teeth and eyes, most of us, and the plants we grow at home, approach more of an "average" status! This plant thrives in a nice humid greenhouse with plenty of light and warm temperatures. Bringing one into an average home during winter months is a real test of survivability. Take cuttings and root them in a sand/peat media each spring and be satisfied with getting one to survive. Forget about it looking good over the winter months. If you can, take cuttings that are four to six inches long. Dip the ends in a rooting hormone and provide some bottom heat. Be sure they get plenty of direct light from the sun, artificial lighting, or a combination of both. The leaf drop your plant has been experiencing could be from an earlier spider mite infestation or possibly scale.

Q: I bought a bag of onions a few months ago. The few I didn’t use have started to sprout. Can I plant them? Do I plant the whole onion or cut out the center and plant that? Can I plant them inside? (E-mail reference)

A: You can plant them, but do it outside. How much of the onion you plant depends on where you live. They need full sunlight in order to thrive. I would throw the onions away if you don't plant them soon.

Q: I have a ficus growing indoors that I’ve had for about five years. The past few months it has looked very droopy and has some yellow leaves. The drainage is very black, almost like strong coffee, when I water it. The tree does not absorb water. (E-mail reference)

A: Try repotting it and locating it outdoors when weather permits. Plant it close to the house on the east or north side. This usually revives most houseplants. Give it some fertilizer when you see some new growth emerging.

Q: One of your readers asked about a "twin sister" shrub that produced a pair of white flowers and orange to red twin fruits in the fall. It sounds like a twinberry honeysuckle. It has flowers that are white to pinkish, with orange, orange/red or red berries.

A: Thanks for writing. You are probably right that it is a twinberry honeysuckle. The reader will appreciate getting the information.

Q: I have to share an experience with you. Last year I forced some hyacinths and tulips to grow. I always leave them in the pots to dry down and plant them in the garden the next summer. Last fall I forgot about them so they didn't get planted. I believe it was early January when I found them on a shelf in the garage where I had thrown them into a flowerpot. They still looked good even after being there through the heat of summer, etc. I planted them as thickly as I could in a pot. I watered them and put them on the garage floor to go through the cool period. I found them coming up a few weeks ago. I moved them to the house and now have beautiful blooming hyacinths with buds on the tulips. I had planned to only keep them alive until I could plant them outdoors but am now enjoying them instead. We are always told to toss forced bulbs because they have spent their energy and will not amount to anything.

A: You write of a good experience with tulips and hyacinths. I'm glad everything worked out for you. Thank you for being a loyal reader of this column.

Q: What is the best soil to use for growing annual flowers in large outdoor pots or whiskey barrels? Can I use garden soil or do you recommend potting soil?

A: Always use potting soil that has good drainage. If you don’t, you’ll be wrestling with that problem all summer long.

Q: I have some questions about calla lily bulbs. I received two that were pre potted. The one at work is sprouting and growing very well. The other bulb is not sprouting at all. How long do they take to sprout and how much should I be watering them? How much sun do they need? How often should I fertilize? (E-mail reference)

A: Calla should be breaking dormancy within a week or two. It is likely a dead tuber if it doesn’t. Water sparingly at first, just enough to moisten the potting soil. Increase the watering as they develop but allow the top half to two-thirds of the potting mix to dry before watering again. Once in full leaf, soak the soil and keep it moist. Don’t worry about overwatering at that point. Give the plants some direct sunlight and bright indirect light while they are in leaf. They can bask in full sunlight while they are dormant, as long as there is no danger of frost or getting soaked with rain. The temperature while they are starting to grow is important. Keep the temperature below 70 degrees or cooler if possible. Fertilize at half strength once every two weeks during active growth.

Q: Someone asked me what to do with her cucumbers. Every year the leaves turn brown and eventually the plants dry up without producing fruit. She dug up a spot on the opposite side of her yard but had the same problem. Any suggestions? (E-mail reference)

A: Cucumbers need good drainage and plenty of sunlight. They shouldn't be watered from above. Use a drip irrigation system or very carefully water them with a hose so as to not get any water splashing on the foliage. She should continue to rotate her planting site.

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: Rich Mattern, (701) 231-6136, richard.mattern@ndsu.nodak.edu

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