The azaleas of early spring, the blaze of color we ache for in the dreary months of winter! The bloom does not last long, the flowers have no scent and the colors may be garish, but a tableau of half-a-dozen azaleas up front is a substitute for a coat of paint for the house.

Nothing beats the azalea for great big banners of color: white for the simple and the pure of heart, red for the passionate, pink for those who go for cute, purple for brooding romantics, and mixtures for most of us mixed breeds. Unlike other plants, azaleas can be transplanted when in bloom--theirs is the instant facelift for the yard. They lack the baroque sophistication of iris or the exotic complexity of the water lily, but they are terrific bloomers--high achievers year after year with no upkeep other than occasional mulching.

They are ideal for what botanists call "a transitional zone" that is neither southern nor northern. They are trou- ble-free, thrive in our acid-rich clay and die only if the winter is especially cold and they are exposed to wind.

Around Washington the azalea is the best-selling flowering shrub--rose is second, rhododendron third. The azalea for Washingtonians, and especially for Virginians, is what the rose was for the Christian Middle Ages and the lily of the valley for the Psalmist--an earthly metaphor for heavenly perfection.

The way Kim Hall, 28, figures it, growing azaleas is a way to make money. Three years ago, he cleared the brambles behind his grandmother's clapboard home in Great Falls, Va., and built a 110-by-25-foot greenhouse out of rough locust poles and standard two- by-fours, layers of polyethylene sheets, chicken wire and snow fence. It's a rough job but he intends to improve it.

Hall reckons that his greenhouse is

large

enough for

10,000 azaleas, and he

began by planting

5,000 cuttings in beds of sand mixed with peat moss.

The azalea is a slow grower; only about 1,000 of Hall's plants are ready to go this season. He plans to sell them at a stand on Old Mill Market Square on Colvin Run Road, off Rte. 7 on the way to Great Falls. His prices are low: $7 for

a three- to four-gallon size

and $3 for a two-gallon size.

The American Plant Food Company, 5258 River Rd., Bethesda, prices azaleas at $3.95 (in a two-gallon pot) to $15.95 and above for larger plants. At Johnson's Flower Center, 4020 Wisconsin Ave. NW, a tiny azalea is $2.95, larger bushes range from $10 to $20.

Hall, who calls himself a landscaper, is interested in no other flowers besides azaleas. "They sell fast," he says. "I use other flowers in my work but I don't care about growing anything else because you end up losing money."