There'll be more vegetable gardeners this year than ever before. The high cost of food is one reason, to say nothing of the high quality of freshly picked vegetables and the fun of growing them.

Specialists recommend soil-testing before the new season. Most soils are acid east of the 100th Americian, a north-south line running down the middle of Minnesota, Mebraska, Kansas, Oklahoma and Texas; many of the soils are too acid for the best growth of vegetables, flowers and lawn grasses.

In fact, a recent summary of more than a thousand soil samples sent to the University of Maryland Soil Testing Laboratory showed that more than 59 percent were too acid for good gardening.

Lime is used to reduce soil acidity, and an application is usually needed every three or four years. A soil test will show how much lime to apply: Too much is as bad as not enough, or worse.

District residents can have their soil tested free at the University of The District of Columbia, 1331 H Street NW; residents of Maryland can have it done at the University of Maryland, and Virginians at Virginia Tech. Phone your county extension agent for instructions on how to take the samples and where to send them.

If soils are sampled properly, so the sample is representative, the test can accurately describe a relatively large area.

If the soil in your garden is acid, lime should be spread evenly and then worked into the soil. Lime moves downward very slowly: An application made to the surface and left there may not reach the root zone for a long time. That's why it's so important to dig it in and mix it thoroughly with the soil before spring planting. Obviously, that's impossible with lawns.

Besides correcting soil acidity, lime supplies calcium and magnesium, which are essential plant nutrients; increases the availability of phosphorus and other elements; stimulates bacterial activity, and indirectly improves the structure of heavy clay soils.

Pulverized or ground limestone is the most popular lime used for farms and gardens. Fineness of grind is the secret of getting it to dissolve rapidly. Acids work only on the outer surface of lime particles, and the more surface exposed, the faster they work.

For best results, use lime ground finely enough for most to pass throught a 100-mesh screen. Such a lime, thoroughly mixed with the soil, will react during the first few months after application. Q: When should I prune my crape myrtle? A: Late winter or early spring just before new growth begins is the best time to prune crape myrtle. It can be pruned severely and new growth will produce flowers this year. Q: I've been given an amaryllis in full bloom. What kind of care does it need? A: Give the plant good light, but no sunlight, and the flowers will last longer. Temperatures should be about 60* to 65* F. at night and 70* to 75* during the day. Water with room-temperature water, when the soil feels dry to touch, until water comes out the drainage hole; wait 15 minutes and empty the saucer. If the pot stands in water for a period of time it may damage roots by depriving them of oxygen. After the flowers are gone, fertilize lightly twice a month to help form next year's bulb.

When the outer leaves start to yellow, cut off all leaves to within an inch of the neck of the bulb, take the bulb out of the soil, store in a cool spot at 50* to 55* and moisten slightly once a month. In the fall when the bulb begins to show signs of growth, pot and start the new blooming cycle. It should bloom within six weeks. Q: I saw some lovely hanging baskets with flowers in them last summer and would like to have some for myself. Are they much trouble to take care of? A: Hanging baskets can add a new dimension to gardening when used to decorate the home, patio or balcony. But to stay attractive, they need constant attention. If they are to be used in a shady location, be sure the plants are kinds that need shade (or sun, if that is where they are to go). Drainage is essential for those used indoors. Outdoor baskets will dry out quickly on hot, sunny, breezy days when humidity is low: they may need to be watered daily. The need for fertilization varies with the kind of plants and their location. Q: In our front yard, we have a big oak tree that must be more than 60 feet tall. We prize it highly. Should we have lightning rods installed onit it to keep it from being struck by lightning? A: Although odds are against the tree being struck, trees are struck and many die every year because of it. The general recommendation is, valuable trees and those growing near homes and other buildings should be given lightning protection. Q: I'd like to grow garlic this year. When is the proper time to plant it? A: Plant garlic in early spring, about the same time as onions. Use only large cloves as seed. Plant them 1" deep, 4" apart in rows 12" apart. Q: I have 20 loblolly pines in my front yard which do not provide shade because they are too tall and skinny. Can I top these trees and get them to spread more? A: It would be much better to remove about half of them and give those remaining room to spread.