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

By Ron Smith, Horticulturist NDSU Extension Service

Q: I read your response to a question about transplanting eastern red cedar. Red cedar trees are terribly invasive. While traveling much of the U.S., we heard over and over how these trees are spreading west because of transplanting and sales. The states that have them say these trees are taking over native trees. Wouldn’t you at least suggest that people should check their state’s invasive species list? (email reference)

A: Your point is well taken. Yes, it is a good idea to check with your state to find out what is on the invasive species list. Usually those listed as invasive are not native to North America. In this case, it is the eastern red cedar. Mother Nature has a way of controlling the spread of invasive species through fire. However, with human settlement moving west, we eliminated that natural phenomenon. The seeds are spread by birds, especially cedar waxwings, and the seedlings get established in just about any soil condition. I guess it would be up to humans to prevent the spread by getting on top of any unwanted seedlings becoming established. Because of the eastern cedar’s durability, the trees are desired for windbreaks and stabilizing an environment that is otherwise untamed because of a lack of plant establishment.

Q: I have a Christmas cactus that I received from my great aunt who was frustrated because she couldn't get it to bloom. I put it outside during the summer. I water the plant when I think of it (not good). As you can see from the photo I’ve attached, about half of the plant's leaves are a dark red and the rest are a vibrant green. I do not fertilize it, but I'm sure I should. Does it need to be transplanted? The soil is hard and compacted. It is flowering nicely and on time this year. (email reference)

A: Yes, it should be transplanted and fertilized but not while it is flowering. Your success in getting the plant to flower comes from your cultural and environmental tactics (decreased warmth and moisture). Wait until spring when the daylight hours are noticeably longer to repot.

Q: My husband and I are looking at buying land south of Grand Forks to use as a garden plot. Since the land is a former farm field, should we be concerned about residual herbicides or pesticides in the soil? We are not trying to get an organic certification. However, we want to know if the food we grow in that soil is safe to eat. Would you recommend chemical residue sampling/testing prior to planting fruit trees and vegetable plants? (email reference)

A: Yes, a simple test will tell the story. Get some corn and bean seeds. One is a monocot (corn), while the other is a dicot (bean). Take some soil from the site where you are planning to establish your garden and sow at least three seeds of each in separate containers. Grow the seeds under lights and heat as you would if you were going to start transplanting for spring planting. If they germinate and produce leaves beyond the cotyledon stage, the soil is fit for growing edible crops. If the foliage that emerges is deviant in form or character and is consistent across the plantings, then the culprit very likely is herbicide residue. If one or the other doesn’t germinate, then test the viability of the seed by soaking the seeds in distilled water to see if any root radicles emerge. The water should barely cover the seed. If they do emerge, then the seed is good but the soil is not.

Q: I have two small apricot plants that I started from seeds. I read that I need two trees together so the trees will bear fruit. Can you tell what type of soil is suitable for these plants and how much water they need? Please help me out. (email reference)

A: If you are planting them indoors, then any quality commercial potting soil will suffice. If you are planting them outdoors, then any soil that will support weed growth will support these trees as well. Apricot trees do not need to be planted together but should be within a few hundred feet of each other. The important point is to have them where they can get ample direct sunlight for at least six to eight hours a day. Also, the trees should be protected from excessive exposure to wind and frost pockets.

Q: I have a question about pruning. I have a large lot that has many bushes and trees that are growing larger. I like to get started with pruning in the fall, but often the weather prevents me from getting it all done. If the plants are dormant in the late fall and early winter, why can’t I do the pruning while the weather might be more advantageous to me? Why does conventional wisdom decree that late winter or early spring is the best time to prune plants that bloom on new growth? (email reference)

A: The best answer I can give to this conventional wisdom practice is that late winter assures that the trees or shrubs are on the way out of dormancy because of increasing day length and warmer temperatures. Late fall/early winter pruning may be practiced where there is an especially heavy load to get through. However, I think they want to make sure the pruning wounds start healing after December. With some folks, if you give them an inch of permission to prune, they take it up to a foot. In other words, it is physiologically and technically correct to prune starting in January. If the date was backed up to Dec. 15, then someone might push it to Dec. 1. If your plants are not zone pushers (not marginally hardy, but fully hardy in your area) and they are in full dormancy, there would be little to no harm to pruning in late fall. Depending on my level of ambition, I have done it myself many times with no negative impacts.

Q: My jade plant is sprouting what I think are roots between leaf joints. Could that be the case or is the plant starting to flower? It has never done this before. It’s healthy and kept on a windowsill. (email reference)

A: If the sprouts are long and stringy, then you are seeing aerial roots. This is a common occurrence for jade plants in their native habitat. It is not common if the jade is a houseplant. If they are roots, then you have done a fantastic job of caring for the plant by giving it an artificial environment that is very close to its natural habitat. If the sprouts are not long and stringy, then you have flower buds developing, which you also should be congratulated for. Enjoy whatever they turn out to be.

Q: There is a park down the street from my apartment where someone has stripped rings of bark out of two of the trees. Is there anything I can do to keep the trees from dying? (San Diego, Calif.)

A: This could just be loose bark, which is common on eucalyptus trees. I’m guessing this is the species you are talking about. Most tree bark doesn’t separate easily from a tree. Eucalyptus trees are an exception. If this is the case, the tree will be fine. However, you should get in touch with someone locally to have the trees properly identified before passing final judgment. Go to http://ucanr.org/County_Offices/ to contact a local University of California Extension Service agent.

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 email ronald.smith@ndsu.edu.


NDSU Agriculture Communication – Jan. 4, 2012

Source:Ron Smith, (701) 231-7971, ronald.smith@ndsu.edu
Editor:Rich Mattern, (701) 231-6136, richard.mattern@ndsu.edu
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