Q: I purchased a beautiful and healthy looking China doll plant from a grocery store about six months ago. I haven’t been able to make it happy. I have it in our bedroom near a northeast facing window, and water it about once a week. It’s in a pot that drains well. The stems near the dirt are brownish. The leaves droop and then fall off. It did look healthier in the summer which makes me think it needs more light and may be getting a draft from the window. (Minot AFB)

A: The China doll is sensitive to drafts, but not central heating systems. In other words, it can tolerate the dry air of winter homes. However, it tends to drop leaves in a home environment probably due to low light plus exposure to an occasional cold blast of wind. Keep in mind that this is a native to Taiwan, so what we might not consider a problem can become one to this tropical beauty. I suggest keeping the soil uniformly moist, and locating it in a bright west or south facing window. Get supplemental lights for it if the cold air coming off the window is too much.

Q: I have a question about the difference between mineral based sod and peat based sod. I wonder what mineral-based refers to. Does it mean that the soil is heavy in minerals (as opposed to the peat, v. organic)? (E-mail reference)

A: Mineral soils basically have less than 20 percent organic carbon. Soils above 20 percent are classed as organic (histosols). To this, there are sub-classifications - fibrists, folists, etc. I don't know how much of a course you want in soils. Contact me if you need more information

Q: I have recently inherited a jade plant from a friend. It was a large plant. My friend cut it down and it has grown back. The soil that it is in has a very strong musty smell. I want to know if I can repot it and how exactly I would go about it. (E-mail reference)

A: Get a good quality potting soil from a local garden supply store or garden center. Knock all of the soil off the roots and clean the pot up with hot, soapy water. Assuming it is a freely draining pot, simply put the plant back in with the potting soil and water it twice. The second time after all the gravitational water has stopped flowing out of the bottom. If it isn't free -flowing, then dump the pot, and get one that is. Make sure the plant is at the same depth it was in the original container and all will be well.

Q: I have a goldfish plant that I bought about three months ago. Since then it has always bloomed with increasing amounts of blooms. About a week ago the leaves started falling off. The tops of the stems are also turning black, almost as if they are rotting. I haven't watered it recently ( I thought it might be overwatering), but I mist it about every other day. We have had a recent temperature drop in Atlanta so I thought that was the cause, but it seems to be getting worse. ( Atlanta, G.A.)

A: You were probably overwatering. These plants should be watered sparingly throughout the year. You are correct in assuming that a temperature change could have a negative impact. They are also susceptible to cyclamen mites and aphids. I suggest watering just enough to keep the soil from drying out completely as the plant may have moved into a rest period. Prune off the blackened stem back into healthy tissue. Try to keep it warm and in bright indirect light. If the plant doesn't improve over the next 2-3 weeks, then it is likely a goner and you’re better off dumping it.

Q: Until now I had two beautiful crown of thorns. I left them out during our first frost. The tops of the plants look wilted but not completely dead. The bottoms still have a pretty green color. I’m wondering what I can do to save these plants? Should I bring them indoors and see what happens or should I go ahead and prune them back? Any fertilizer? (E-mail reference)

A: I think you are going to get away with this plant surviving. I would do nothing at this point, as you might have shocked the plant into a dormant or rest period. No fertilizer until new growth is evident over the next 6-8 weeks.

Q: I was recently in Punta del Este, Uruguay, and noticed a beautiful tree with a delightful silver tone to the underside of the leaves. My friend in Uruguay told me this tree is called Alamo Plateado in Spanish. As best I can discern, this translates to Silver Poplar. Am I correct? (E-mail reference)

A: If you are correct in identifying this tree as silver poplar - Populus alba - then it is a tree that you don't want on your property. It is a very tough tree that can take anything that gets thrown at it short of a direct hit from a bomb. The root system would be a major problem. They are invasive and suckering. Its asset is that it can survive just about anything!

Q: Any suggestions on lilly of the valley? They are overtaking my back yard. (E-mail reference)

A: Write a book if you can figure out what to do about lily of the valley! Their waxy leaves resist herbicides. I have found that pick-axing the plants is the only way to get rid of it. Death, taxes, and lily of the valley.

Q: My dracaena marginata has grown to two canes near five feet tall and had been doing fine. One side lost all of its leaves, rebudded and began to grow, but then died. The other side was fine, but one day I came home to find it hanging down as if somebody had broken it. There was softness in the cane but it wasn't broken as you would break a stick. The leaves were fine, so I strapped it up with a chopstick (makes a great splint) and hoped for the best. More areas have gotten soft and the leaves are almost dead. Can I cut them off below where it is soft and hope it buds? (E-mail reference)

A: I would suggest cutting the canes back several inches below the soft areas. This will force new buds to eventually break further down the cane and develop into a nice healthy plant. Somehow your dracaena has picked up a fungal canker disease that is girdling the stem. What I have done in the past with success is to cut the plant back to about a 6-inch stub, then taken the cane and cut it up into about 4-5-inch pieces and laid them horizontally in dampened sphagnum moss for about 5-6 weeks. In that time some new buds and growth developed on one end, while roots developed on the other. In the meantime, the mother plant began breaking new growth as well!