ASK THE GARDENERS. Questions & Answers.

Q Would you please explain how to get a poinsettia to bloom for Christmas? Each year I cut my plant back in May and set it outdoors alongside our house. I bring it back indoors in October but it doesn't get red until late January. R. E. T. Essex, Md.

Poinsettias are light-sensitive plants and must have treatment similar to the light it gets in its native habitat.

In late September, set plant in a totally dark place, or cover it with a black cloth or thick paper bag every evening so that it gets only about 10 hours of good light. A simple way to do this is to ``put it to bed'' about 6 p.m. every day, then set it in bright light again at about 8 a.m. the next morning. Follow this procedure until mid November.

For information on poinsettia care send a self-addressed, stamped envelope for our bulletin: How to Grow Poinsettias.

If you have a question about your garden, inside or out, send it, along with a self-addressed, stamped envelope, to the Garden Page, The Christian Science Monitor, One Norway Street, Boston, Mass. 02115. Doc and Katy Abraham are nationally known horticulturists.