Lisianthus, the new flower rage; tasty Mexican Jicama

Q I bought some beautiful pink, white, and violet flowers from a florist. Partly opened ones are like tulips, but fully opened they are more like poppies. I asked the store clerk the name and he said they were Lizzyanthus (he wasn't sure of the spelling). Is it possible to get seed for sowing outdoors. They've already lasted a week with no sign of wilting.

Seeds of this new ''flower rage'' are being offered in catalogs for the first time. You may find them under Eustoma or Lisianthus russellianus.

In wildflower books, the parent plant is listed as Eustoma (yew STO ma) russellianum, or Prairie Gentian. Japanese plant breeders used the plant (native to the American Southwest) to produce this beautiful offspring.

It can be grown in greenhouses as pot plants or cut flowers, as well as outdoors as an annual.

In the North the seed should be started early indoors, because the time from sprouting to bloom is about five months. Seedsmen will supply cultural instructions. Some bedding-plant growers are offering started plants this spring.

Q Friends of ours have crown vetch growing on a steep bank. Knowing we would like to plant some, they told us to help ourselves to seeds when ripe. Two years ago and again last year we tried planting it on our bank, but we get no crown vetch whatsoever. We scratch up the soil surface, spread rotted compost on top, then scatter the seeds and keep it watered. What are we doing wrong?

Crown vetch is a legume (in the pea family) which has tubercles on its roots, allowing it to use nitrogen from the air. Bacteria are associated with the tubercles, and crown vetch won't grow unless the particular bacteria are in the soil.

Usually an inoculant is needed to introduce the bacteria. It can be obtained from seed companies that sell crown vetch, or sometimes it is available at state experiment stations.

Q While visiting in Mexico, we were served a salad containing pieces of a crisp, white-fleshed vegetable which tasted like coconut. The name given us was jicama, but we would like to identify it further and know a source.

Jicama (pronounced hee-KAH-ma) produces tasty edible roots from 3 to 6 inches in diameter, depending on the growing season and soil. The botanical name is Pachyrhizus erosus or P. tuberosus.

While the tubers are delicious, the showy purple and white flower heads, seed pods, and leaves are toxic. For this reason, and for better growth of the tubers , it is best to keep the flower heads snipped off.

From seeds, four warm months will produce small tubers; larger ones take eight to nine months. Seeds should be started indoors where growing season is less than 120 days. Seed companies listing Jicama are: Exotica Seed Company, 8033 Sunset Boulevard, Hollywood, Calif. 90046; J.L. Hudson Seedsmen, PO Box 1058, Redwood City, Calif. 94064; and Nichols Garden Nursery, 1190 Pacific Highway, Albany, Ore. 97321.

Q I bought a packet of Sweetheart strawberry seeds last fall, intending to sow them in late January. My husband says it's too late now because they won't bear before frost next fall. Why can't I grow them in hanging baskets and move to our sun porch in the fall? Aren't they an everbearing type?

Sweetheart strawberries are delicious everbearers that start producing fruit about four months after the seeds are sown.

The year before last we sowed ours in April. They started bearing outdoors in August and we moved them indoors in the fall, where they continued bearing all winter. In the spring, however, they took a respite when we moved them outdoors. They had just commenced again when one of our helpers forgot to water them.

We now have new seedlings coming along. They're everything the seedsmen say they are!