Q: I’ve had a Christmas cactus for a couple of years but I never got it to bloom. What are the secrets to making it bloom? I know it needs to be kept in the dark during October, but do I continue to water it? (E-mail reference)

A: The eternal question of getting a Christmas cactus to bloom. Beginning in the fall, and through the winter, give the Christmas cactus only a little water, keeping the soil barely moist. It needs 12-plus hours of uninterrupted darkness, in a cool room (55 degrees F. best) and plenty of direct sunshine during the day. Keep up that regime until buds form on the ends of the leaves. Once set, they will continue to develop and open, their rate and longevity dependent on the temperature of the room the plant happens to be in - the cooler the better.

Often what happens is the buds form and then drop off without opening. It’s due mostly to low humidity and high room temperatures in the winter. If you can tolerate it, keep your house at 65-70 degrees. Set the plant on a bed of pebbles immersed in water. That will keep the humidity high around the plant. Having said all of this, I know of at least a half-dozen people who never go through this routine and have a beautiful flowering Christmas cactus every year. Some people just have a magic touch!

Q: We are going to use our fireplace this winter. Would it be beneficial to use the wood ash on our lawn? If so, do we spread it as soon as it cools during winter, or should we collect it and wait until spring? Also, do we simply distribute it by hand on top of the lawn surface (is it effective without being incorporated into the soil)? (E-mail reference)

A: I would suggest storing it dry until the spring thaw. Frozen ground doesn't absorb nutrients and mixing the ash with wet snow will degrade some of the nutrients the ash contains. Spread it at a rate of about 5-10 pounds per 100 square feet. For maximum effect, do right after a core aeration of your lawn. Otherwise the potassium will work it's way into the soil slowly with the spring and summer rains.

Q: There was something on TV about planting potatoes in a garbage can. Supposedly you could then grow potatoes inside during the winter. Do you have any information on that? (Cando, N.D.)

A: I doubt that you could generate enough light indoors to seriously "produce" potatoes. You might get a semblance of a vine to grow under lights or in a sunny window, but I doubt that it could be pulled off in a garbage can. Isn't it amazing the questions that get thrown at us?

Q: I have over a dozen hibiscus that have been inside in winter and outside on the deck in summer for several years. Last spring I noticed that one plant wasn't blooming, so I pruned it severely. When I brought it in this fall it had grown out again but still did not bloom while the rest bloomed profusely. What happened? I don't have enough south windows for all my geraniums. If I were to use a four foot fluorescent grow light, how high above the plants should it be? (Brookings, S.D.)

A: No idea why the one didn't bloom. As for the fluorescent light, keep it about 12 inches above the top of the plants.

Q: Is a box elder tree supposed to be outside? A friend gave it to me and said it was a house plant. I have been finding box elder bugs so I assume it is a box elder tree. If it is meant to be outside, will I still have the bugs indoors? Will these bugs hurt our home in any way? If it can be an indoor tree, how do I get rid of the bugs? (E-mail reference)

A: Just when I think I have heard it all, then someone tells me that a boxelder tree is a houseplant. I suppose anything is possible, but I would get it out of the house, and if possible, way out in your yard. Keep it away from anything the tree can damage when it drops branches or collapses in 20-30 years. Boxelder bugs are harmless, but annoying critters. I assume you live somewhere where winter weather is starting to close in, and typical of the insect, it is seeking shelter from the cold. They are pests, but not harmful to one's home.

Q: We have a Black Hills spruce that we planted last year. It is now about six feet tall. We want to eventually keep it down to around 10 feet or so if practical. What is the proper method and timing for trimming the top and side branches? It has a good leader on it now and is doing well. (Horace, N.D.)

A: You will have to seasonally shear the tree, which is best done with a machete. In the spring, cut the soft new shoots that have just elongated to one-half their length. This is not a practical or recommended practice. It’s just what we used to do when we intended them to be cut trees for Christmas. Spruce and pine trees should rarely be pruned.