Something happens to Lenwood Cooper on warm bright Saturdays, the kind with 78-degree breezes and unassuming white clouds.

He begins to feel downright handy.

Yesterday was such a day for many of Cooper's ilk in the Washington area. If half the population seemed to be at play, the other half seemed intent on hard labor.

While the former group headed to the monuments or the parks or the pleasure boats, the latter made a beeline to the nearest hardware, nursery or building supply stores -- homeowners seized by the spring-improvement syndrome.

Cooper, an engineer for the D.C. school system, and his wife Lilly found themselves at the Hechinger store at 17th Street and Benning Rd. NE yesterday morning, intending "to look around." Instead, they bought a weeder-trimmer, a lawn mower and several gallons of paint -- all vital tools, it turned out, for the fun afternoon of clipping, trimming and primping that the couple planned at their Walnut Street NE home.

"It's not in such bad shape around there now," Cooper said, as he waited outside the store to load his car. "But it might be when I get through with it."

Bustling around him, the signs of noble resolve and domestic responsibility were obvious. Couples rolled shopping carts stacked high with lumber and bags of peat toward their cars. The cars idled at the curb, hatchbacks and trunks thrown open to receive loads of potted plants and window screens. Everyone seemed in a great hurry to get home.

Maybe they were simply manic to get outdoors after several days of chilly, procrastinating rain. Maybe they were feeling guilty about their property after a winter's worth of neglect. And maybe, like Delores Johnson, they were simply thinking ahead.

Johnson, a Georgetown University Hospital employe, surveyed the contents of her shopping cart. Yes, she came to the supply store to buy lumber to complete the building of her back yard picnic table; that lumber was definitely on her shopping list. But the grill? The charcoal? The wood for new porch banisters? The paint to cover the new porch banisters?

"I got to thinking about sitting outside," said Johnson, who lives on V Street SE, "and I wanted it to be nice when I get around to sitting outside."

Other area home and garden supply stores reported similar hordes of fixer-uppers yesterday. At Wolf Trap Nursery and Greenhouse in Vienna, the marigolds, petunias and impatiens were "really moving," a clerk reported. At Lowe's Building Materials in Bowie, customers snapped up landscaping timbers, mulch and fertilizer. At Johnson's Flower & Garden Center, 4020 Wisconsin Ave. NW, they turned to the tomato plants, the begonias and the zucchini.

Like many other customers of the day, Bob and Kym Rushing, owners of a Capitol Hill town house, also fell prey to at least one impulse buy. Along with picket fencing for their back yard and a cart full of other merchandise, they left Hechinger with a $2.79 product called Scent-Off that is "guaranteed to discourage dogs from trees and shrubs."

"Do I feel stupid buying this or what?" Bob Rushing, a 27-year-old accountant, asked a little sheepishly.

But Kym Rushing, also 27 and an advertising agency employe, firmly defended the purchase. "I feel really protective about my tree," she said.