The annual spring offensive has opened in the parks of the nation's capital: a mass deployment of 160,000 botanical troops, ranging from the Ringo rose geranium to the Moonshot marigold.

From the National Capital Parks' glass-and-concrete command center on Ohio Drive a mechanized division of dump trucks and rototillers sortied for the government's seasonal assault on the senses.

Led by 14-year veteran Mel Coby, the gardening force struck first at McPherson Square last Friday, uprooting an advance guard of 6,600 red Princeps tulips and digging in 1,000 Carefree Crimson geraniums backed up by 2,000 Moonshots.

The fatigued tulips will be rotated behind the lines for use next year in a different theater, possibly Fairfax or Rockville.

Similar strikes during the next six weeks will hit 45 of the city's seasonal gardens, where Coby and his nine-member task force plant explosions of color as shock therapy for the wintry soul.

From Union Station to the Kennedy Center, from the Pulaski Statue to Hains Point, flower power in Washington is as carefully organized as a Pentagon war game, complete with biological weapons employed to search and destroy.

Plastic sheeting, in body-bag black, will mark beds being gassed to combat parasites and disease. A seven-man task force will plow the ground to a depth of eight inches for the Super Elfin Impatiens and the Bright Eyes Vinca.

Already in place and functioning is an army of 18,000 pansies, standing guard at Fountain No. 4, just east of the Tidal Basin inlet at the entrance to East Potomac Park. The Snow Cloud petunias are on standby.

The spring offensive is one of three major floral pushes from the park service upon the green space of Washington, where once only an occasional dandelion bloomed.

Since former first lady Lady Bird Johnson inaugurated her beautification campaign in the mid-'60s, tulips planted in the fall have given way each early May to summer annuals, which bow in turn to chrysanthemums in the early fall.

Their numbers have ebbed and flowed with the tides of budget largesse and inflation. Regional horticulturist Jim Lindsay, supreme commander of the capital's floral wars, has seen the price of tulips double from 7 and 8 cents apiece three years ago to 14 cents today. Daffodils,12 cents apiece in 1980, now cost about 17 cents.

He and other park officials, however, say that the residents and tourists of Washington still get a lot of bloom for the buck.

The bulk of Washington's annual flower bill amounts to roughly $245,000, according to National Capital Parks spokeswoman Sandra Alley. The money comes from the National Capital Parks' $80 million annual budget, out of the$9 million alloted to the NCP Central Region: 1,100 acres that stretch roughly from the Capitol to the Kennedy Center.

George Washington Parkway and Rock Creek Park, each a separate NCP region, pay separately for the thousands of daffodils that line their roads--a major portion of some 300,000 daffodils that National Capital Parks grew this year.

Like any good general, Lindsay gives credit for his victories to the men in the field.

"They decide what goes where, not me," he says. "They submit their plan, and unless it's a matter of cost or something very unusual, I approve what they ask for."

Men such as general foreman Milton Boston, a bespectacled 20-year veteran with a professorial mien, "have a great deal of pride in their work," Lindsay says. "They are very, very good."

The gardeners also decide how and when to rotate colors and plants in a particular area, he says. The decisions are made a year in advance, so Lindsay can put the orders out for bids and give the suppliers sufficient lead time; not every nursery keeps 2,200 Ball Best Begonias on its shelf.

Boston says that the flower wars are both more routine and more rewarding than most people realize. The vast majority of his men's time, he says, is spent cutting grass, picking up paper, clipping shrubs and performing normal landscaping chores.

Yet there is very little turnover among his men, he says, possibly in part because of the public's obvious appreciation of what they do, particularly during the floral onslaughts of spring, summer and fall.

"The men enjoy that," Boston says, "and when somebody enjoys what they're doing, they stay with the job. They take pride in it and they do it well."

Tourists, he says, are always asking how to get their tulips to grow like those in the parks of Washington.

There is, he and Lindsay say, no great magic to it: Simply buy top quality bulbs (12 cents apiece and up), till the beds to a depth of eight inches, plant the bulbs all the same depth, and space them six inches apart.

"Most people make the mistake of putting their tulips in too late in the fall," Boston says. "You want to put them in in October, if possible. Early enough so they can get some growth in before the first frost."

Old tulips, like old soldiers, never die, they're just traded away. Technically they could be recycled for the following year, but the labor costs of sorting and storing the exhumed bulbs would push the tulip bill to $1.60 a flower, Lindsay says. So in early May the Park Service gives them away by the truckload, mashed stems, dead blooms and all, to local government agencies in the area and orders new bulbs for next year.

When flower funds are tight, Lindsay eliminates planting in some beds, switches species in others, and occasionally has plants spaced further apart. Few people notice such cutbacks, he says, due to the attention given to such "high visibility areas" as Lafayette and Farragut squares by people like Coby and Boston.

Already, high maintenance plants like roses and azaleas largely have faded from the flower beds of the District, and there will be no summer flowers planted this year at spots like Franklin Park and the Tea House at the end of Hains Point.

But in case a little money shows up for something new, Lindsay has a project all ready. One of his favorites, and that of Washington visitors, is the "tulip library" of some 85 species beside the TidalBasin.

In West Potomac Park, near the boat landing south of the Lincoln Memorial, he would love to see a daffodil library.

"You know, there must be between 75 and 100 species of daffodils, narcissus and jonquils, and there's really nothing there now," Lindsay says. "It'd be a great thing to see."

Another campaign in the war of the flowers. And when he talks of it, the general smiles.