Ellen H. Nagy, Dunkirk, writes:

Do you have any information on "Night-blooming Seres"? It has a most exotic bloom which opens only one night of the year. Perhaps it has another name.

A. The plant you inquire about is Night-blooming Cereus. Information about it can be found in gardening encyclopedias under its botanical name, Hyocereus undatus. It is a clambering tropical cactus that may grow 25 feet tall if supported. It blooms at night, usually about 8 p.m.; the large white flowers remain open till morning. It requires warm temperatures, plenty of bright light, and a loose, well-drained soil. It benefits from plenty of water during the growing season. It can be pruned to maintain a manageable size. Cuttings, especially pieces with aerial roots, root readily. Because it is a tropical cactus it must be kept indoors in the winter.

Mrs. L. Lane, the District:

Is there a way to start a pineapple plant of my own from a crown cutting?

A. The recent Indoor Gardener column on bromeliads stimulated readers' questions on how to grow pineapples.

Pineapple (Ananas comosus) may be grown from pineapple tops. Cut off top with about one inch of fruit. Trim the flesh away to hard stringy tissue. Strip off several layers of the lower leaves and set the crown upside down on a jar or pot. Allow the cut surface to dry for three days to a week.

Choose a pot that is at least 6 inches deep and provide for good water drainage by using a generous supply of gravel or broken pot pieces in the bottom.

Use a loose, gritty, prepared soil mix - the kind sold for African violets is suitable. The basses of the lowest leaves of the crown should be placed level with the soil surface. Tamp the soil firmly around the base. Insert a stake or two to hold the plant upright. Give it bright light but not direct sunlight.

Fertilize at planting time, and every two or three months after that, with water soluble houseplant fertilizer.

Water the plant only when the soil feels dry to the touch. It will not root or grow in soil that is always wet.

After several years, your plant may flower and produce a small fruit. This fruit is coarse and tough but you can use it to start a new plant. Although the pineapple plant will live and produce attractive foliage for many years it will not bloom again.

May L. Hall, Silver Spring:

I have a beautiful plant called "Madonna's Tears." I would like to know why it never blooms.

Also have a zebra plant; the leaves keep falling off and nothing ever happens to that.

A. The problem of leaf drop ofAphelandra (zebra plant) can be overcome by prunning. Pruning helps to keep the plant bushy. Cut the stems back to one or two pairs of leaves. Use the cuttings to propagate more plants.

Flowering depends on diffused sunlight. Blooms normally appear in autumn. After flowering, the plant will rest, during which time watering can be reduced.

When it is actively growing give it a complete fertilizer every 10 days to two weeks.A moist soil at all times is a positive requirement, but be sure that the soil drains well. Alphelandra has many fine delicate roots which are susceptible to rot if the growing medium is too wet.

References available to me fail to list a plant called "Madonna's Tears."

Marian Hyler, Alexandria:

My venerable schefflera has never flourished but it is really suffering since moving here from Boston. It sat in a moving truck last week for 10 hours. The branches are now mostly bare and the remaining foliage is curing. In Boston it was under a Gro-Lux bulb six hours a day. Now it is in a sunnier apartment. I hate to see the tree die.

A. Your schefflera is undoubedly expressing the shock of its changed environment. If it wasn't too sturdy to begin with, the move was even more trying in terms of fluctuations in humidity, light and temperature. The confinement in a moving van is an additional hazard as the plant may have been subjected to gas fumes and temperatures either too high or too low.

Keep the schefflera in diffused light for a while. Remove about an inch of soil from the pot and replace it with fresh potting mix. When you water the plant, soak it. Then let the surface of the soil become dry and remain dry for a day or two before soaking it again. Keep the plant out of drafts and away from the air-conditioner vents.

When there is evidence of new growth - that is, when leaf buds begin to sprout - fertilize with a general water soluble houseplant fertilizer once a month.

Schefflera is a good plant for east or west windows. When it is actively growing, place it where it will get full sun or bright indirect light.

Indoor gardening question may be addressed to Jane Steffey at The Weekly, The Washington Post, 1150 15th St. NW, Washington, D.C. 20071. Please include your address and telephone number.