Q Quite some time ago you wrote about the pot plant with the colorful daisylike flowers named cineraria. I made a mental note to start some of the seeds in my small greenhouse so I could have them blooming in March or April. Is it too late to do this?
Because cinerarias (Senecio cruentus) take from 51/2 to 6 months from seed to bloom, florists sow the seeds in October for Easter bloom. Another reason for October sowing is the need for cool night temperatures for best growth and bud formation, conditions more easily provided from November to March.
Although seeds need a temperature of 70 degrees F. to germinate, a night temperature of 55 to 60 degrees is desirable after the seedlings are transplanted into 21/2-inch pots. When they are 31/2 to 4 inches tall, they should be transplanted into 5-inch pots and grown at a night temperature of between 45 and 50 degrees for good bud formation and development.
You can sow seeds anytime if you can maintain a night temperature no higher than 55 degrees for a period of about 31/2 months after the seedlings are transplanted.
Q We have several white pine trees that were green and fluffy looking until mid-October. Then many of the needles started turning yellow and dropping off. However, needles at the ends of branches still remain nice and green. Can you identify the problem and tell us what to do about it?
Each species of needled evergreen drops its needles at regular intervals during its lifetime. White pine, under normal conditions, drop their needles about every 18 months. New needles grow on the ends of the branches each spring. The oldest ones remain until the second autumn, usually mid to late October.
Since you still have the lush green growth of this past spring, your tree is acting normally.
Q My seven-year-old son has asked me to write for instructions on the proper care for rabbit's-foot fern. He has had three, and each one has had the fuzzy roots and pretty fronds for about a month, but then gradually turns brown and its ''feet'' fall off as well. What is wrong?
Rabbit's-foot fern (Davallia) needs to have plenty of humidity for the fronds and furry rhizomes to thrive. They also need warm temperatures (70 to 80 degrees F.) during the day, with no less than 55 degrees at night, since they are from the warm, humid tropic regions.
Most homes do not have these conditions year round, especially during the winter when the furnace is on.
Davallia does best in a bright north window with a soil that's kept ''just moist'' at all times, but never soggy. Some people are successful in growing them in an orchid soil of 1 part fine bark chips and 1 part coarse perlite. Others use a commercial potting soil mixed with equal amounts of sphagnum peat moss and coarse perlite. They need very little fertilizer but can be given liquid feedings at half strength every six or seven months.
Q A month ago my husband gave me a plant stand with five adjustable shelves and fluorescent lights over each shelf. I have already started marigolds, double petunias, and herbs. I am keeping the lights 4 inches above the plants and they appear to be doing well. Would it be possible to start delphiniums from seeds, to be set outdoors in the spring? If so, when should I start them? Will they bloom the first year?
If you start them in January or February and transplant the seedlings to pots when large enough to handle, then plant them outdoors in May or June, they should bloom in late summer or early fall.
Once they are established, they will bloom in June or July, and usually a couple of months later with smaller flowers.
If you have a question about your garden, inside or out, send it to the Garden Page, The Christian Science Monitor, One Norway Street, Boston, Mass. 02115.