Soggy soils compact easily. Stay off the lawn as much as possible this time of year, when the soil is soggy wet. Soil compaction is almost certain to occur, and it's hard to keep grass growing in compacted soil: The roots can't get the oxygen they need to function.

This is a good time of the year to fertilize grape vines and fruit trees. The fertilizer stimulates plant growth and increases yields. It isn't a good idea to fertilize those that haven't started to bear, unless they need it badly, because it may delay them in starting to produce fruit.

Give each grape vine about two pints of 10-6-4 fertilizer. Spread it on the ground around the vine, keeping three or four inches away from the trunk. Work the fertilizer into the soil gently with your hands or a hoe. Don't go more than an inch deep, because many of the feeder roots are close to the surface and can be damaged.

Spread 10-6-4 fertilizer on the ground around fruit trees, from near the trunk to slightly beyond the spread of the branches. Use four pounds per 100 square feet. Work the fertilizer into the mulch if there is one, water it in if there is sod, and work it gently into the soil if there is neither mulch or sod.

Go easy on fertilizing pear trees. Nitrogen may increase the likelihood of their becoming infected with the fire blight disease of pears. Bartlett, Clapps Favorite, Bosc, Flemish Beauty and Sheldon varieties are very susceptible to the disease.

Burpee Seeds Co., Warminster, Pa. 18974, is testing a new and radically different tomato that will stay fresh on open shelves in a moderately cool place for as much as six to twelve weeks after picking. They call it "Longkeeper."

Although Longkeeper fruits can't compare with ripe juicy Big Boys or Big Girls eaten fresh from the vine in summer, the color, taste and texture are generally superior to tomatoes available in stores in December and January, they say.

Send for their free catalog, which will tell you how to get a few seeds of Longkeeper for testing.

Q I'm trying to get organized on planting a vegetable garden this year. When do I plant seeds of lettuce, English peas, cabbage, parsley and cantaloupes ?

A Plant seed of head lettuce indoors about March 1 and small plants outdoors about April 1; seed of English peas outdoors about March 15; seed of cabbage indoors February 10 to March 1 and plants outdoors as soon as they're about two inches tall; seed of parsley outdoors about April 1, soak the seeds in warm water for 24 hours before sowing; and seed of cantaloupe outdoors about May 15. Do not cover the seed of lettuce because it needs light to germinate.

Q We want to start a terrarium garden. What kind of glass container is necessary ?

A Brandy snifters, water bottles, glass canisters, cracker jars, almost any clear glass container large enough to hold a plant and a small amount of soil can be used. Don't use one with colored glass. Colored glass transmits only light of its own color and absorbs all other colors. It also reduces light intensity and can cause abnormal plant growth. Don't use a green container -- green light is of no use to plants and they will soon die. Clean the container and make sure it is free of detergent residue. Place a layer of gravel in the bottom of the container to collect and hold excess water. Add a layer of charcoal, about half an inch deep, and then add a soil mix sparingly.

Q Can the ashes from our fireplace be of any value to the garden ?

A The ashes can be used to help condition the garden and flower beds. Analysis of the ashes will vary, depending on the type of wood you burn. Generally, they will contain about 45 percent calcium carbonate, a form of lime. They will have 5 to 10 percent potash and about 2 percent phosphorus. Store them in a dry place. If they are piled outside and exposed to the weather, they will lose much of their low nutrient value through leaching.

Q Can sludge be used in our vegetable garden for soil improvement

A-It is not considered advisable to use digested sludge (method of treatment) on root crops or on vegetables that are to be eaten raw. Activated sludge has no bad odor and harmful pathogenic organisms are killed during the heat treatment.