One advantage to buying vegetable seeds through catalogues, despite the extra expense, is the new varieties, as distinct from the tried-and-true seeds sold locally.

"Burpee invites you to try Explorer potato" is the message on the back of this spring's catalogue. It's really a seed potato -- that is, a potato seed. Burpee will send a trial pack of 50 seeds for a quarter with any catalogue order. It's said to produce usable potatoes in three months. You have to start the seeds early, though, indoors.

The popularity of sugar snap peas has predictably spawned improvements on the single variety available until this year. Hastings offers the Sugarrae, which holds two pods per node (twice as many as the current sugar snap) and the vines are more squat, at two to three feet, compared to seven feet. Park's has a new Sugarbon snap pea said to mature three weeks earlier than the currently available sugar snap, and be more compact, at about two feet. Both new varieties mature at 70 days.

New beans are, well, perennial. Both Gurney and Burgess offer the Daisy Bush Bean, which bears fruit above the foliage, growing like a daisy. But it's slow-maturing, so don't expect it to produce along with your other bush beans.

For apartment dwellers, Burpee has developed a new tomato you can grow on a balcony, the Basket King. It's also fairly early-maturing, at under two months from the time the plant is set out.

There are so many kinds of lettuce that adding a couple of new ones seems overkill, but Burpee and hastings each have. Burpee's Red Salad Bowl bears maroon leaves and is very slow-bolting. Hastings' Grand Rapids, despite its name, is bred for Southern gardens and matures in just 43 days. Hastings, incidentally, is good for this area, specializing in Southern gardens.

W. ATLEE BURPEE CO., Warminister, Pa. 18974. BURGESS SEED AND PLANT CO., Bloomington, Ill. 61701. GURNEY'S, Yankton, S.D. 57079. HASTING'S, P.O. Box 4274, Atlanta, Ga. 30302. PARK SEED, P.O. Box 31, Greenwood, S.C. 29646.