March 29, 2001

Hortiscope

Ronald C. Smith, Horticulturist
NDSU Extension Service

Q: We live on 5 acres north of Bismarck and have established tree rows. We would like to plant grass in them this year to help with the weeds. What advice do you have for a low maintenance grass? Also part of our land is still "native" grasses (I use the term loosely) and has become overrun with thistles. We spray with Roundup but they just keep coming. Is there any kind of preemergent weed killer we could use? If so, when do we apply? They seem to keep on coming up all summer long! (E-mail reference, Bismarck, N.D.)

A: The grass I would recommend between your trees would be a sheep fescue/hard fescue combination. Both are bunch grasses that are drought tolerant and shade tolerant -- up to a point. The sheep fescue is more drought tolerant and somewhat shade tolerant; the hard fescue is more shade tolerant and somewhat drought tolerant. One will fill in where the other fails. I would suggest using Confront to control thistle. It is a product that has triclopyr and clopyralid as active ingredients and has done an excellent job of taking thistle out of turf for me, because of the excellent systemic action it has. Canada thistle has to be prevented from going to seed, either by mowing before it flowers or getting it with a herbicide like Confront. This would include perimeter areas around your property, as the seed can travel great distances. The best remedy for controlling Canada thistle is persistence and aggressiveness on your part. Don't give up the vigil!

Q: I have a spider plant (about three or four of them, actually, in a single 8-inch pot), which has been in that pot for a year or longer. I took the plantlets from a parent which I no longer have. How long does it takes one of these to mature and begin making its own plantlets? I see no signs of any spikes emerging from their centers, though they all seem quite healthy and now might even be a bit pot-bound. Is that, by the way, a good or bad thing for these plants? I see root tips beginning to sneak out of the drain hole in the bottom. Does that mean repotting time again? I don't overwater, and let it dry well between waterings, then I do give it a drink with weak plant food each time. But still no signs of babies. Any advice? And if I may, a question regarding my clivia. I've had it for about 2 1/2 years now, and admittedly it hung around rather neglected in a grower's pot for it's first year with me. But I did eventually pot it up in regular potting soil.

While it appears healthy and does keep producing new foliage, it doesn't have any sign of sending up a flower stalk. Again, how old does it have to be, and does it require special handling to make flowers come out? (E-mail reference, Louisville, Ky.)

A: The spider plant should produce wiry stems this spring with small white flowers, followed by spiderettes or tiny plants. You don't need to be fertilizing it each time you water; they require fertilization about three or four times a year. They are the most adaptable of all houseplants, growing under widely varying conditions. Don't worry, it will have plenty of babies pretty soon!

You have gone from the very easy to the more challenging with the clivia. Without a doubt, it will not bloom unless it is left in an unheated room, no fertilizer, and just enough water to keep it from wilting during the winter months. I am talking about a room that goes down into the 40s or 50s in winter, during which it needs bright light, but it should avoid direct sunlight in summer.

It is fussy. Don't move the pot when it is in flower, and don't repot unless the roots are pushing the plant out of the container.

Q: My mother has several standard African violets ( not the minis). She has them on a window sill above her sink, in a north window. She says that until recently they have been absolute blooming fools. She has been trying to find out how to go about separating the mother plant from the six or eight sets of its clones. She had repotted them as they were pot bound , and soon noticed that the smaller plants were growing from the base of the mother plant. They have stopped blooming, I would assume that they are putting the energy into the baby plants. One plant has so many babies that it no longer has room in the pot. She would like to know how to go about dividing them as the small plants have no roots. There is also no type of infestation of insects, crown rot or anything else. Her plants are very healthy, I think she is alarmed because they are no longer blooming. What should she do? (E-mail reference, R.I.)

A: Everything has to stop blooming sometime! Blooming is akin to running a marathon for a plant. The better shape it is in, the better it can perform, but even top performers need some time to recover or "rest." It has been less than 80 years since the first African violet has been introduced as a houseplant, becoming in that time a world-wide favorite of amateurs and experts alike. African violets have five basic needs: steady warmth, careful watering, good light, high humidity, and regular feeding. Keeping the plants moderately root-bound, and using a plastic pot when repotting is essential. The secret to continuous (or nearly so) blooming is to provide excellent flourescent light on a year-'round basis. Back in the late 1920s and up until the late '50s and early '60s, African violets had to be handled with kid gloves. With the bewildering varieties and clones that have come about since then, the violet isn't near as fussy, allowing it to be grown and appreciated by more interested houseplant gardeners. The easiest way to propagate is to divide the crown with a razor blade or a very sharp knife. It sounds like you could get about four divisions from the crowns you describe. Or, as is commonly done, remove a leaf with a long petiole at the edge of the rosette of plantlets that you are describing, and insert it (or them) into a pot containing a 50/50 mix of peat moss and perlite or vermiculite. Moisten well, and cover with a polyethylene bag until new growth is evident, in four to eight weeks. Tell your mom not to be alarmed. African violets today are pretty tough individuals, and as long as she waters them properly, and provides ample bright (but not direct sunlight) light, they should continue to produce well for her.

Q: I have a ficus tree growing outside of my home in Florida. We had a very bad frost this winter (bad for Florida) and my ficus tree looks to be half dead. The back of the tree (closest to the house) still has green leaves hanging from it, but the front of the tree and the top seem to be dead, no leaves and dry branches. I am wondering of I should cut back the tree, but I feel that this would make virtually half of the tree disappear because most of it is leafless. Please let me know what I should do. (E-mail reference, Fla.)

A: I suggest cutting the ficus back as best you can to green wood, trying your best to maintain as much symmetry as possible. There is a chance this will stimulate some new growth development that will result in an attractive looking tree. If the tree doesn't respond in about six weeks after this treatment, very likely you are not going to ever get a response, or you may get a response that you don't like; but it is worth the effort to see what will happen before making another expensive purchase.

Q: I just bought a crown of thorns the other day and I am not sure how to take care of it. Could you give me some tips on how to water it and how much light it needs? (E-mail reference)

A: Give crown of thorns all the light available -- in other words, as much direct sunlight as possible, for as long as possible, for maximum flowering. Give them regular waterings during their period of active growth, allowing the top inch to dry between each watering occurrence. Fertilize once a month as long as the plant is showing active growth.

Q: I am very interested in using arborvitae trees to create a wall along the edge of my yard. The wall of trees I'm envisioning needs to cover approximately 125 feet. The soil here is mostly black dirt with some rocks( no bigger that a fist on average) scattered about. It’s also flat ground and well drained. Ideally I would like to plant 4- to 5-foot trees ( I have access to a tree spade) because I would like them to reach 6 to 7 feet in the next three years or so ( to block out the view of a busy county road ). This plan may become very expensive very quick. Also, this wall of trees I’m planning will be within 15 feet of a line of 30-foot tall green ash trees ( the new wall of trees will have direct sunlight until 3 to 4 p.m. when the ash trees will provide shade). Can you recommend any cheaper alternatives to create an attractive looking " natural " wall of either trees or shrubs? Are there any other species that look good and are relatively fast growers? (E-mail reference, Hastings, Minn.)

A: I wouldn't advise doing what you are thinking of for a couple of reasons: The roots of the ash trees are going to be extremely competitive with those evergreens, which are going to have about a third to half of their root system left behind when they are spaded. Smaller plants grown in containers will have 100 percent of their roots and grow much faster than those that have been severed. Second, you are right about the expense! Save your money for something better. Just what I'll let you decide. For a "natural" look, why not plant some sub-canopy species like dogwood or honeysuckle shrubs? They will grow nicely, providing flowers and fruit which will attract the birds and butterflies and will not be subject to winter burn as evergreens would.

Q: I inherited a Hoya from my grandmother 15 years ago; it was her mother’s. I'm not sure how old it is, but it's at least 40 plus years. It has never flowered since I've had it. It experienced a growth spurt when it was transplanted six years ago, but otherwise, it has stayed the same size. About three years ago, it started developing tiny brown, raised bumps on the underside of the leaves and the stems. I've tried soapy water and an insecticide, but nothing has worked. It doesn't seem to harm the plant, but I really don't want to lose it. I would really appreciate your advice. (E-mail reference, Howell, Mich.)

A: It sounds like your plant is getting attacked by armored scale, or, it could simply be edema, a swelling that causes "bumps" in some of the epidermal cells of the leaves. If you could send me a sample of a leaf, packed dry in zip-lock bag, I'd take a quick look at it to see just what it might be. You don't want to be handling insecticides if it isn't necessary. The common insect on hoya plants is mealy bug. It is easily identified, whereas scale can be a fooler.

Q: I have a question about winter burn injury on evergreens. Can anti-dessicants only be effectively applied in the fall right before winter sets in, or are there other times of the year that it can work? (E-mail reference, Cando, N.D.)

A: An anti-desiccant application can go on again in the late winter/early spring while the soil is still frozen. In most cases, the evergreens recover with new growth, just looking a little worse for the wear of the winter. If the warm weather continues above freezing these next few days, that would be a good time to reapply the anti-desiccant.

Q: I've recently noticed that a small swarm of flies has invaded my spider plant. They are small and seem to have settled more on the soil than the leaves, but there isn't any visible leaf damage. Any ideas on how I can rid myself of these pests? (E-mail reference)

A: The swarm of flies are likely what are called "fungus gnats." They are more pest than pestilence. If you can obtain some insecticidal soap in a "pump" bottle, simply spray when you see them swarming. It will take several applications to get them under control, but this material is harmless to us and your plant, so you don't have to worry about over-use.

Q: What would you recommend as the best red, white and russet potatoes for storage? (E-mail reference, Bottineau, N.D.)

A: Here is a list of the potatoes that are good for storage: 'All-Blue', blue -purple skin and flesh, late; 'Caribe', bluish-purple skin, white flesh, early; 'Carola' buff skin, yellow flesh, late;

'Norgold M', russet skin, white flesh, early; 'Norland', light red skin, white flesh, early;

'Pontiac' (also known as ‘Red Pontiac’, red skin, white flesh early; 'Russet Burbank', russet skin, white flesh, midseason; 'Yellow Finn', yellow skin, dark yellow flesh, mid to late season;

'Yukon Gold', yellow skin, yellow flesh, early to midseason.

Q: We have a peace lily about 2 feet high and 2 feet wide. It is in the original container, diameter about 8 inches. It has one very tall flower and another one coming. The leaves are turning brown on the ends and along the edges. We have been giving it two or three glasses of water three times a week or it starts to droop. Any information on the proper care of this plant will be appreciated. (Rogers, N.D.)

A: You are essentially doing the right thing. Peace lilies need to be kept continually moist. The browning along the edges is due to salts either in the water or from fertilization. Try using distilled water for a while to see if any subsequent leaves lack the foliar burning.

Q: I'm worried. I have many different types of lilac bushes, common lilacs to specialty lilacs. Some are almost 10 feet high. I just read a question from another reader regarding Miss Canada and when to prune her. I removed Miss Canada's spent flowers in early summer as I always have with my other lilacs. Miss Canada is a new one for me. Did I remove her new buds for this season? Should I have just left her alone? Will she flower? She is my most beautiful lilac bush. She grows so gracefully. (E-mail reference)

A: The 'Miss Canada' lilac is a cultivar of the late lilac ( Syringa villosa), which produces flowers on the current season's flush of growth, rather on last year's like the common lilac. So, in a nutshell, you have nothing to be worried about. If my answer to a former reader left you confused, I apologize. Your 'Miss Canada' should bloom beautifully this spring for you. Enjoy!

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: Gary Moran, (701) 231-7865, gmoran@ndsuext.nodak.edu