If you still have your poinsettia from last Christmas, the time has come to make a decision about it. You can either keep it as a year-round foliage plant indoors, or you can cut it back, put it outdoors for the summer, and bring it into bloom again for next Christmas.

Generally, it's difficult to regrow the plant to bloom again so that it's nearly as good as one professionally grown; but it can be done.

Cut the stems back to about four to six inches above the soil, removing almost all the side branches. This will cause buds in the uppermost leaf axils to develop and grow.

Change the plant to a pot one or two sizes larger. When you remove the root ball from the old pot, shake off loose soil slightly, exposing the root tips; this helps stimulate new root growth. Use a pre-mixed potting soil or make your own by mixing two parts of good garden topsoil with one part of peat and one part of vermiculite, perlite or sand.

Put a few small rocks in the bottom of the pot over the drainage hole and cover them with potting soil. Put the root ball on top and fill around it with more potting soil. Pack the new soil with a blunt stick to eliminate air pockets, and keep the soil half an inch below the rim for watering.

After danger of spring frosts is past and night temperatures stay above 50 degrees F., the plant can be put outdoors in light shade for the summer. Fertilize it lightly every two weeks, following the label directions on how much fertilizer to use.

Prune or pinch the stems back as desired for shape during the summer, and bring the plant back indoors before nights dip below 50 degreesF.

It will start to set buds when the nights become 14 hours long, with uninterrupted darkness from about 6 p.m. to 8 a.m. Usually this darkness is needed from about October 1 to early December. Any stray light at night during this period interferes with the flowering process -- even light from a 10-watt bulb will keep it from blooming. The plant must have 14 hours of continuous darkness until full bloom. This can be achieved by covering it with a large cardboard box or putting it in a closet every night. Night temperatures during this period should be 62 degrees to 67 degrees F. -- lower temperatures may delay blooming Provide full natural light during daytime hours.

Q: I tasted some Jerusalem artichoke my sister grew in her garden last summer, and it was delicious. I want to grow it myself; can you tell me where I can find seed?

A: It's started from tubers, and very few seed houses have them. They can be ordered from Park Seed Co., Greenwood, South Carolina 29647. Send for a free catalogue. The tubers should be planted in the spring, as early as the soil can be worked.

Q: A limb died on our sugar maple tree, and we cut it off in late March. The wound continues to bleed even though we applied tree paint.How do we stop the bleeding?

A: Tree paint will not stop bleeding -- in fact, it has little value other than cosmetic. Bleeding occurs when the sap is rising in the spring; after the tree has developed its leaves, the bleeding stops.

Q: I want to plant a ligustrum hedge to separate our vegetable garden from the yard. My husband thinks it might damage the vegetables that grow close to it. Do you agree?

A: If the ligustrum is pruned so it doesn't spread too far, and if it's north or west of the vegetable garden so it doesn't shade the vegetables, it can't harm them.

Q: Last spring I planted two young crabapples. They were covered with blossoms, but this year they have only one or two. Can you tell me what could be wrong?

A: Transplanting is a major operation for a tree, particularly one large enough to bloom, and it usually takes a year or two before it blooms normally. Just be patient with it.

Q: I've heard that sweet corn should be planted in several short rows rather than a single long row. Is that true?

A: Multiple rows can provide better pollination, which means more and better corn.

Q: When is the best time to prune azaleas? Ours are getting too tall and lanky.

A: Light pruning can be done almost any time of the year except late summer. The best time for rather heavy pruning is late winter or early spring. Azaleas are likely to become tall and leggy when they are crowded or heavily shaded.

Q. Our flowering crababble tree has lost most of its leaves. Can you tell me what's wrong? Some of the leaves are enclosed.

A: The problem is a fungus disease called apple scab. Wet, cool spring weather helps the disease to spread. Remove and destroy the dead leaves, since they can cause new infections.

Q: We are able to get railroad ties for use in our garden to make steps and borders and so forth. Is there any reason they should not be used for these purposes?

A: Most railroad ties have been treated with creosote to preserve the wood, and this material is deadly to plants. Of course, it's possible to use the ties in such a way that your plants won't be damaged.

Q: Is there a way to keep squirrels from eating off young leaf buds on our tree? Can a tree replace leaves so destroyed?

A: Most mature trees and shrubs in fair health have many more leaves than they actually need for food production; losing some of them should have no harmful effect.

Q: We have an asparagus bed five years old; how long can we keep cutting it in the spring?

A: Cutting of an asparagus bed five years old usually may continue for about eight weeks. Harvesting should be stopped when there's a general decrease in the length and diameter of the spears.

Q: What's the best time of day to water our lawn? I've been told it shouldn't be done during the afternoon.

A: If there is a best time to water the lawn, it's probably early morning. Watering in early evening may encourage diseases, since the grass will be wet all night.

Q: Can you tell me how to clean and sterilize old clay pots?

A: Scrub them with a stiff brush and warm water. If there are spots of encrusted fertilizer salts, scrape them off with a knife or steel wool. If the plant that was in it previously is suspected of having been diseased, soak the pot in boiling water for about 10 minutes.

Q: We planted grass seeds in our lawn and they came up fine. Should we now water the lawn in times of little rain?

A: Grass turns brown when the soil is very dry, but a drought severe enough to kill most lawn grasses isn't likely here. Watering during dry weather will be helpful, but it should be done thoroughly, wetting the soil to a depth of 6" to 9".

Q: We have a new home and I have just finished planting a lot of azaleas.I've been told to mulch them with peat moss. Is this the best material to use?

A: Mulching newly planted azaleas is very important and one of the best materials to use is pine bark. The mulch should be 2" or 3" deep. Peat may not be a good mulching material because during long dry periods it forms an impervious surface which prevents water penetration into the soil. When it dries out, it's hard to get it wet again.