The past 10 years has seen the greening, and flowering, of much of the nation's capital.

The National Park Service has spent more than $250 million to fill its 46,000 acres of area parkland - 8,500 in the District - with millions of new flowers, shrubs and trees. It has turned its local parks into summer wonderlands, with new arts and sports programs, new museums, theaters and indoor and outdoor festivals going on almost daily during summer months.

The $43 million being spent on area parks this year is 12 times more than in 1967, when $3.5 million was the entire Park Service operating budget here. On landscape maintenance alone, for upkeep and improvement of parks around the nation's capital, the Park Service now is spending $4.3 million.

In contrast, the District of Columbia is spenidng less money than it did only six years ago for upkeep and improvement of the 2,000 acres of city-owned open space, although the city now has several hundred acres of additional parkland to care for than it did in 1970.

But what the District does have, its 1,200 acres of recreation space at 150 playgrounds, plus small plots at street corners, schools and other public buildings, is frequently barren and ill-kept. The District has no parks department whose primary responsibility is to plant or care for flowers and, as far as any official can remember, the half dozen different city agencies that are responsible for open space have done little planting.

"The District government is concerned about people, not flowers . . . but what the government forgets is that people like flowers and trees and parks, they want to live near them," says one keeper of the city's parkland, discouraged with what he feels is the continued downgrading of parks and park maintenance.

The District beautification office, which got millions of dollars in federal and District funds and millions in private donations to spruce up neighborhoods here in the late 1960s, goes out of existence this summer. Its four employees this week received reduction in force (RIF) notices that their jobs are being abolished.

The Society for a More Beautiful National Capital, founded by Lady Bird Johnson in the mid 1960s and donor of more than $3 million to help spark the rejuvenation of city parks, went out of business last year, "unnoticed - because there is no longer any interest at the top, no leadership concerned about the city's open space," said Richard Brillantine, a landscape architect and director of the soon-to-be-defunct office of beautification.

In the past six years the recreation department's maintenance budget has been cut by more than $1 million, and its maintenance staff cut by more than 200 employees, even though there are now more recreation areas to care for, according to one recreation official.

"We have more than 100 buildings to maintain, buildings in use 10-12 hours a day, six days a week, and we can't even put a man at each one," says Robert Fleming, administrative officer of the recreation department.

The long proposed new city parks and recreation department, touted as at least a partial cure for city park ills - because it would consolidate park maintenance now spread among more than six city departments - is still under study by a mayor-appointed task force after almost three years.

"We're just about ready to recommend something to the mayor . . . and when he decides, there'll be a press release on it," says George Jenkins, assistant director for executive management in the city's office of management and budget, which is heading the task force study.

The decline of Washington's city parks began in 1970, some officials say, when the Park Service ended its maintenance of most city recreation areas, for which the District had been paying $6.5 million a year. But instead of using that additional money for parks or recreation, District officials transferred it to other accounts. Of the $19.5 million the District would have paid the Park Service for park maintenance in 1970, 1971 and 1972, the District spent only $213,000 of it on parks or recreation, city officials said in 1973.

But the appearance of District parks, is quickly forgotten in the magnificent downtown floral display put on by the National Park Service.

It was only 10 years ago that the Park Service here did little more than mow its extensive lawns around Washington and tend the few formal public flower beds that bloomed during Washington's long summer.

Since then, in an explosion of activity, the Park Service has: Relandscaped the Mall, Columbia Island, Lafayette Square and most other downtown parks, built COnstitution Gardens and Turkey Run Farm, expanded the new C & O Canal National Historial Park, taken under its wing the Kennedy Center, Wolf Trap Farm, the National Visitors Center, Harper's Ferry, the Frederick Douglass and Clara Barton homes and the Sewall-Belmont House on Capitol Hill, restored and opened Ford's Theater and Pierce Mill, inaugurated a tourmobile service around the Mall, built 64 miles of bicycle trails, and jointly sponsored the Folklife Festival. Among other things.

In projects designed for area residents it has spent more than $5 million to build an indoor ice skating rink at Fort DuPont and an outdoor skating rink and pavillion in Anacostia Park, launched a summer in the parks program that spends more than $2 million a year making area parks and programs among the most inviting anywhere. It includes a summer Shakespeare festival, National Symphony, jazz and Carter Baron Amphitheater concerts, downtown lunch-time concerts, and programs at just about every Park Service building and park in the area.

And the flowers. Garneners, supervised by some of the 264 horticulturalists on the Park Service staff, planted by hand more than 600,000 bulbs last fall, added hundreds of cherry trees to the Tidal Basin, and are now digging in 130,000 summer-flowering plants.

Its parks are not just lovely to look at but provide most of the area's playing fields as well, home to dozens of rugby, polo, softball, baseball, soccer, football, field hockey and cricket teams. The area's two largest tennis court compexes, 22 courts at 16th and Kennedy Streets NW and 21 courts on Hains POint, are run by a concessioner for the Park Service, as are its golf courses and both its sailboat and powerboat marinas.

For quiet picnics nad walks the most popular area parks alos belong to the Park Service, including Fort Washington - which attracts more than 1 million barbecuers a year - Fort Hunt, Great Falls park, Carderock, East and West Potomac Parks and Harper's Ferry, the farthest flung outpost in the National Capital Regions' domain of 350 parks and "reservations."

But for basketball, tennis around the corner at 129 courts located at city playgrounds, swimming and recreation center programs for children, the District is the major provider. There are now 20 outdoor pools, one indoor-outdoor and eight year-round indoor pools open - or opening this weekend - to cool local residents.