The first plants - Pelargonium triste - were brought from South Africa to England by plantsman John Tradescant in the early 17th century. The fragrant and ivy geraniums soon followed and the coveted flowers first became conservatory plants, then garden specimens.

Generally considered to be an annual, geraniums are actually a tender perennial. Even though they thrive on warm weather, they won't be killed by the first frost but will actually perk up when the cooler nights and still-warm days of fall arrive.

There are more than 200 species of geraniums but only a few are widely grown. Garden geraniums generally fall into four basic types: common, ivy-leaved, Martha Washington and scented-leaf.

Relatively pest free, geraniums can be susceptible to a couple problems in the home garden:

* Botrytis, an air-borne fungus that first causes a mold on the blooms, which should be removed and destroyed, not composted. It tends to show up when days are warm and nights are cool enough to create a ``drippy'' dew in the morning or on overcast days.

* Geranium rust, especially in Virginia, causes dusty, orange rings on the bottoms of leaves. The plant defoliates. Remove affected leaves, or better yet, remove the plant, putting it in a bag so the disease doesn't spread.

Geraniums, however, are among the easiest and prettiest to grow. Purchase plants with healthy, dark green leaves with no discolored spots above or underneath, and look for fairly compact growth because leggy stems indicate the plant was grown in poor light.

GERANIUM AT A GLANCE

COMMON NAME: Geranium

SPECIES: Pelargonium (pel-ar-go'ni-um)

FORM: Upright plant, main stem with branching stems that have flowers above mound of foliage.

SIZE: 1-2 feet tall, 12-18 inches wide.

EXPOSURE: Full sun to part shade

LEAVES: Green, fan-shaped, fuzzy, concentric markings.

FLOWERS: Late spring to first hard frost; rose, white, salmon, pink, bright red clusters made up of small flat, open-face flowers.

CULTURE: Well-drained, medium-rich, acidic soil. To start from seed, sow indoors 8-10 weeks before last frost date due; transplant outdoors after frost danger past. Let dry out between waterings. Feed frequently, every two weeks or use time-release fertilizer.

USES: Hanging baskets, deck or patio containers, window boxes, massed in garden. Look good with lobelia, vinca vine, parsley, petunias, verbena, dusty miller, ageratum and asparagus fern. Take cuttings in early September to root easily for winter houseplants. Some gardeners winter over plants by removing soil from roots, placing plant upside down in a paper bag and hanging in a dark, dry, cool place; others keep pots of geraniums in an unheated but non-freezing garage, bringing the pots outdoors on warm, sunny winter days.

PINCHING: Remove faded blossoms and stems.