March 27, 2003

Hortiscope

Ronald C. Smith, Horticulturist
NDSU Extension Service

Q: I have a three year old spider plant that is healthy but recently the plant leaves started bending in the middle. I thought it was the weight of the leaves but the new leaves are doing the same thing. What can I do to fix the problem? (E-mail reference)

A: No idea! I have never seen or heard of that malady before. If it doesn't seem to be affecting the otherwise healthy characteristics of the plant, don't give it another thought. Consider your plant to be unique amongst the millions of spider plants in people's homes.

Q: My fiancé brought a small bonsai home from the Philippines about two weeks ago. To bring it back we had to clear the root of any dirt. We followed all of the planting and care instructions after we returned to Minnesota. At first we thought it looked bad because it had to adjust but no matter what we do, it stays very dry. Is there anything we can do? Please help bring my bonsai back to life! (E-mail reference)

A: Sorry, but I have no magic power to do that. If I did, no one would ever let me ever sleep!

Bonsai is a special way of growing a plant that is not for the novice gardener. It is something that needs studying, beginning with easily grown plants that are very forgiving of our human foibles. You then move on, with experience gained, to more challenging species. I suggest visiting your local garden centers or florist shops to see if they have some locally produced bonsai plants that you grow to gain experience. It is never a good idea to attempt to bring a plant in from another country because it is too much of a hassle and can lead to some disease/insect problems with our native species.

Q: Do you have any suggestions for dealing with powdery mildew on house plants? (Jamestown, N.D.)

A: Try moving the plants to an area with increased circulation, or simply turn on a fan. The mildew can be washed off with insecticidal soap. Even though this is for insect control, it also does a good job of cleaning off fungus. If both of these fail, then Schultz's Fungicide 3, a neem oil preparation. should do the trick.

Q: I have a coreopsis moonbeam that is getting worse each year. The plants are smaller and coming up later in the spring. When they do come up, the leaves are so light green that I give them a small dose of iron. It seems to help but not a lot. I planted a small pink coreopsis two years ago that never did grow. Since we have so much clay I've added compost, manure and some sand to get the soil in better shape. The plants get several hours of sun each day during the spring and summer. I can't figure out what it is that I'm missing. (Moorhead, Minn.)

A: Coreopsis needs well-drained soil and full sun. The nutrient status should be moderate as they get too tall and floppy with regular fertilization. From what you are telling me, you are doing enough of the right things that you should be getting blooms and survivability out of the plants.

Sorry I can't be more of a help.

Q: Deer ate about 20 of my arborvitae leaving only a tuft of green on the top. Will the trees grow back to normal? How long will it take or should I pull them out and plant a shrub or tree that is deer resistant? We use the trees as a privacy fence. Do you have any suggestion on a fast- growing shrub or plant that would be deer resistant? (E-mail reference)

A: The plants are shot in my opinion. They will survive but they won’t serve your purpose aesthetically or functionally. Deer-resistant plants are almost an oxymoron. I don't know where you live, but here in the Midwest, those that have had their landscape and crops ravaged by deer call them rats with antlers! I would encourage you to replant with whatever you wish. Spray Ro-Pell or Cayenne pepper spray on the foliage on a regular basis. You can also ring the planting with low-voltage wire that will give them a gentle zing and send them off elsewhere to feed.

I can send you information to help you control deer activity on your property but results are not guaranteed!

Q: We moved into a house last year that has lilacs in the front and side of the house that are about 16 feet high and very thick at the top but very sparse at the bottom with lots of dead trees in between. We want to get these under control and have them thick from the ground up and about 6 feet high. What is the best thing to do? I have been given two very different opinions, cut all the way to the ground and never cut all the way down. (E-mail reference.)

A: Include this with death and taxes as far as certainty goes: cutting old, tall lilacs right back to the ground in early spring, before new growth begins, will result in a flush of growth that you can then control to your horticultural hearts content. If the plants are dead, then of course, nothing will result. But if, as you say, they are green on top and bare in the middle, they will respond.

Cutting them at the 6-foot level will leave ugly stumps that you will not be happy with.

Q: Would you please tell me if I can round out a potentilla bush? Mine is really unruly and I would like to round it. Someone told me it would not bloom if I did that. (E-mail reference)

A: Most blooming deciduous shrubs should never be rounded out. Selective pruning should be followed by removal of the oldest canes right back to the soil line each year. This keeps the plant in an attractive informal form and provides continuous blooming along with fresh new growth. The rounding out will leave a bunch of sticks with a witch's broom type of growth, something completely unnatural.

Q: How old do burr oak trees have to be before they start to produce acorns? (E-mail reference)

A: I really don't know how many years it would take. It could take 5 to 10 years before the plant is mature enough to enter into a sexually reproductive stage of growth?

Q: I purchased a schefflera plant a week ago which I haven't watered. It is about 28 inches high. The plant is in a 10-inch pot and has many shoots. The soil feels very dry but I don't want to over-water which is a mistake I made with another plant. Please give me watering instructions. Also, when checking the soil it seemed like there were more roots than soil. It's really beautiful but I'm starting to get some yellow leaves. (E-mail reference)

A: Water enough to completely soak the soil mass then allow the top 2/3's to 3/4's to dry before watering again. When the plant is at rest, it should only get enough water to keep the mixture from completely drying out. If there seems more root mass than soil, I would suggest repotting in the next nominal size pot.

Q: Recently a basketball fell on my Christmas cactus breaking of three stems with roots. The plant is just starting to bloom and has about five stems with roots left. Will my plant survive? (E-mail reference)

A: Just continue to give it the care you have in the past, minus the dropping basketball.

Q: Is Preen weed preventor harmful to birds? I want to sprinkle some beneath a bird feeder to prevent the bird seed from sprouting but I don't want to harm any birds that may ingest it. (E-mail reference)

A: Yes, it is harmful to birds. If you have trouble with seed sprouting, nuke it in the microwave for two minutes at full power before placing in the feeder. That will kill the embryo and prevent germination and won’t harm the birds.

Q: Is the ground I use for tomatoes, cucumbers, peppers and herbs contaminated if the neighbor's cats use it for a litter box? Since I share these veggies with family and others, should I just forget it and plant grass? I am concerned the ground might be toxic. (E-mail reference)

A: No, the ground is not toxic for growing tomatoes or other veggies. I would certainly try to discourage the cats from using the garden as their digging activity and their urine may damage the plants. Try placing a cage over the plants when they are first set out to discourage the cats. Also, you might want to plant a trap crop of catnip to attract the cats to that location and not your veggie garden. If you can get a long-range squirt gun, fill it with vinegar and squirt the bounders when they get near your garden. It won't hurt them but they sure don't like the vinegar!

Q: I am writing in regard to my jade plant. I have always loved jade and its unique appearance. My plant is doing just fine but I’m wondering if you have any suggestions on how to encourage the base of the plant to thicken? It is a very full jade and is currently about 6 inches tall. I just repotted it in Shultz cacti potting soil and have been using a light Miracle-Gro mixture along with Osmacote. I believe that the Osmacote is 13-13-13. Is this optimal for jade? Lastly, I have read all of your suggestions on watering but how do I check for appropriate dryness before I water again? (E-mail reference)

A: Stick your thumb or finger into the soil, weigh the plant or get a moisture sensor. If you think it needs water, wait another day. Come up with a method that you can consistently perform to determine the correct time of watering. It sounds like you are over-fertilizing your Jade. It doesn't need the Osmocote. There is usually enough fertilizer in the potting soil to last a few months. The plant should only be fertilized when it is in an active growth phase so it won’t get too leggy and soft. At 6 inches in size, you are a long way away from needing to worry about the thickness of the base of the plant. It will happen naturally as it ages.

Q: I received a crown of thorns about a year ago and it flowers all the time. It has gotten very big. Do I need to repot it any time soon? (E-mail reference)

A: The crown of thorn needs to be repotted every other year sometime during the spring season. Congratulations on being so successful in growing this very dramatically beautiful plant!

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.

###

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