May 1, 2003

Hortiscope

Ronald C. Smith, Horticulturist
NDSU Extension Service

Q: I have a question regarding pruning a mancana ash tree. The tree is 12 feet tall and has developed a second leader. Would removing the secondary leader ruin the canopy of the mature tree? (Fargo, N.D.)

A: Removing the secondary leader shouldn't be a problem but get it done this week if possible, as trees are starting to leaf out.

Q: A friend gave me a few pieces of her jade plant. I placed them in water but now part of the stem has turned brown. Should I cut the stem or just place it in the soil without water? (E-mail reference)

A: Cut off the brown part of the stem and place it in well-drained media. It must be kept moist. It should be rooting for you in six weeks or less.

Q: I planted five arborvitae in mid-August of last summer. We had an unusually hot and dry summer, so I watered the plants frequently. They seemed to be doing okay, but toward fall the leaves closest to the truck turned brown and died. The plants seem to have survived our harsh winter. I don't know if they are just dying a slow death and I should start over or if I should give them more time. If they are worth saving, should I pull off all of the dead foliage and branches closest to the trunk then apply some Miracid? (E-mail reference)

A: The dropping of the dead foliage nearest the trunk is normal, just like us shedding our old hair. Don't pull any of the foliage off because it will defoliate at its own pace. In the meantime, it would not hurt if you want to apply some Miracid a couple of times this summer.

Q: I have a jade that is fifteen years old that is quite large and still in the same pot. The top is so heavy that it has been sitting on a table leaning on the window for years. The two large stalks are at least 1 1/2 inch in diameter with many healthy leaves on the top. It has now been moved and is leaning on something else, but I’m afraid it is going to break or die. Its look has changed since moving. (E-mail reference)

A: Get a good, sharp pair of pruning shears and cut the plant back to a more normal size.

Q: I would like to plant an evergreen hedge for privacy. The two-story house directly behind me is quite a bit higher than my house and appears to look down on my deck and house. I don’t have a lot of space to work with between properties. Spruce and pines would be too large and would hang on my neighbors’ property. A local landscaper recommends techny arborvitae. What would you recommend? Does Arborvitae attract a large number of flies? Does this occur all growing season? This would be close to my deck and outdoor eating area and I don't want to create a problem. I've read where nigra arborvitae are taller than techny. Are they just as durable? (Bismarck, N.D.)

A: Nigra arborvitae does get taller, reportedly up to 30 feet and are said to be very durable. Fly attraction should not be a problem but insects will naturally gravitate to any shrub or hedge for shelter and food, so you will not be bug free.

Q: I have two large maple trees in my yard. The seeds fell all over the yard so they are growing everywhere. I’m pulling them up but they are in the grass. Is there anything I can use to kill the seeds and not hurt my grass, flowers or other trees? (E-mail reference)

A: Find something else to worry about. The maple seedlings will die out with normal lawn care -- mowing, playing, etc. Any broadleaf herbicide will take care of them but I don't like making herbicide recommendations for something that can be controlled easily without its use.

Q: My husband is wondering if we can pot our peonies in huge pots so we can move them around our property as we see fit. He doesn't like to mow around them and have all the foliage in the way after they're done blooming. After blooming we'd move them to a less conspicuous part of the yard to finish out the year. (Sioux City, IA)

A: I see no reason why peonies couldn't be handled this way. It would require more care on your part because peonies, once established, can pretty much be forgotten. This is not so with containerized plants. Watering and fertilization would be needed and some protection during the winter months although your winters in Iowa are mild compared to ours in North Dakota.

Q: I planted a new lawn last fall. When can I start to fertilize and kill the weeds? Can granules be used or should I use liquid sprays? (Salem, S.D.)

A: The grass should be fertilized about 5-7 days either side of the Memorial Day weekend. Herbicide can be applied sometime after the third mowing. Damage will occur if applied when the grass is too tender. Be sure to get the dilution correct and don't over-apply.

Q: We have strange trees growing in our evergreen windbreak. They have black berries but the birds won't eat them. Someone told us they are buckthorns. We have cut out a few of them but, like a bad penny, they keep coming back. I've also heard there is a spike one can buy that will kill a tree. Do you know if there is such a thing, its name and where it can be purchased? (Eagle Bend, Minn.)

A: In Minnesota the buckthorn is considered a noxious weed. The DNR has a program for controlling it. There is also an organization in Minnesota called Trees Trust ( www.treetrust.org ) that can help. Their phone number is (651) 644-5800. They will give you a prescription process to follow in order to get rid of this pest.

Q: I was told there is a variety of grass that can be planted that only grows about 6-8 inches and isn’t very invasive. The grass would be planted between tree rows so hopefully the grass wouldn’t need much care. Any thoughts? (Mohall, N.D.)

A: It is called sheep fescue. It will not attract sheep or win a beauty contest but it will be a functional grass topping out at 6-8 inches. It’s a good grass to use on an area such as you described. Being non-rhizomatous, it should be sown thickly, about 3-4 pounds per 1000 square feet, to make a dense stand.

Q: I know a family that wants to grow sweet corn for local farmers’ markets. They want to plant a number of different varieties but are worried about cross pollination. What distance is needed to avoid cross pollination? (Cavalier, N.D.)

A: Sometimes the maturity of the different varieties of corn will prevent cross pollination. If that isn't the case, then as much distance as possible needs to be kept between the varieties, sometimes as much as 500 feet since corn is a wind-pollinated crop. I’m grossly dating myself now, but I grew an acre of sweet corn for market purposes when I had my small farm in New York. I simply planted three varieties -- early, mid-season and late. By the time the early one tasseled out and fertilized the ears, the mid-season was just starting to tassel.

Q: I recently purchased a spider plant that has baby spiders. I’m wondering when or if there is a correct time to remove the spiders and start new plants. (E-mail reference)

A: It isn't necessary to remove the spiderettes unless you want to start a new one. They add to the decorative quality of the plant.

If your intent is to propagate, the best way is to take a pot full of soil and place one of the spiderettes in it. Pin it down and keep it attached to the mother plant. You’ll need to water it while it roots in its new location. Once rooted, snip it from the mother plant and nurture it to adulthood.

Q: I have read articles about people wanting to get rid of their black walnut trees because they consider them weeds. I’m trying to grow trees from nuts that I have acquired. What is the best way to get them started? I have about fifty nuts in black shells. Do I soak them in water with or without the shell? They have been in a box in my shed so they have been subject to below zero temperatures. How long should I soak them or is soaking them the wrong thing to do? (Parkston, S.D.)

A: The black walnut is indeed a very valuable tree. You have met the stratification requirements for germination but they may have dried out from low relative humidity. Your best bet is to collect the nuts in the fall right after they have fallen from the tree and then remove the outer husks. After cleaning, separate the unfilled nuts from the filled ones by floating them in water. The floaters are dumped. Place the seed either in the ground where you want them to grow or in containers for transplanting Keep them moist until freeze-up. You can expect an average of 50 percent germination.

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