HERE ARE some questions about fruit, vegetable and house plants that readers have written in:

Q. I want to plant asparagus in the spring. Is it better to buy plants or use seed?

A. Specialists recommend buying plants so you are able to harvest a year sooner.

Q. I'd like to increase my number of philodendrons. Is it best to get seed or take cuttings?

A. Most house plants, particularly foliage plants, do not bloom or produce viable seed. They usually root well from cuttings, which should be 4 to 6 inches in length, taken from healthy, vigorously growing plants. Use a sharp knife to prevent crushing the stem. Remove leaves from 2 inches of the bottom of the stem to make it easier to stick the cutting. Plant the cutting 1 to 1 1/2 inches deep. Enclose the potted cutting in a plastic bag which allows the cutting to breath but prevents loss of water. The cutting should not require additional watering until well rooted which usually occurs in two to six weeks.

Q. I want to plant some blueberries, which kind is best? What do they need?

A. Highbush varieties are considered best, the berries are bigger and sweeter than most other kinds. Be sure to buy at least two varieties (three are even better) for cross-pollination. They require a rather acid soil, if you can grow azaleas and rhododenrons, you are okay for the Highbush blueberries. They also need good drainage and to be watered regularly during dry weather.

Q. My home-grown Irish potatoes have a sweet taste. Do you know why?

A. Potatoes stored at too low a temperature accumulate sugar and develop a definite sweet taste. They should be stored at about 40 degrees. If sweetening occurs, one to three weeks at ordinary room temperature restores the natural flavor. Stored at 50 degrees to 60 degrees they have better texture, color and flavor when cooked but sprout unless used soon.

Q. I have four apple trees I spray faithfully but I still get brown spots on my apples. I've been told it is due to apple maggots. How do I control them?

A. It may be due to apple scab or apple maggots. Spraying with an allpurpose fruit tree spraycontaining captan and methoxychlor should take care of it. Follow directions on the label for mix and application. Apply the first spray just before the blossoms open, when they look very pink; the second spray when 90 percent of the flower petals have fallen; the next two sprays about two weeks apart; and the next two sprays three weeks apart. A tank-type sprayer can be used for a dwarf tree, a power sprayer for a regular kind. Cover the leaves, branches, everything. If you can't do it yourself, get a tree service to do it for you. Miss one spray and you are in trouble.

Q. Our Concord grapes, only a few on a bunch get ripe at a time. What causes it?

A. It may be due to the vine being allowed to bear too heavily, which also will cause low sugar content and poor flavor. Don't pick them until most of the berries are fully ripe.