IN APPROXIMATE numbers, Rock Creek Park consists of 2,200 acres. Woodland covers 2,080 acres. The remaining 120 acres are lawn. For the next few months, 10 of the lawn acres are to be set aside by the National Park Service for a program it calls "meadows." That means that the government's lawn won't be cut in several areas of the park. Replacing the mowers will be what is called "ecological succession," which means the meadows will grow to whatever heights sun, rain and chlorophyll can raise them.

In going ahead with its free-the-grass program, the Park Service is justifiably nervous.It knows that people, not to mention government employees, who don't tend their lawns can rile the tidy-minded. Last year, a Fairfax citizen had to defend his honeysuckle, dandelions (used in the family's homemade soup) and wild florabunda roses against the county health department, which declared his lot a neighborhood menace. An Akron, Ohio, court recently ruled in favor of a vegetarian who let her lawn grow. In Wisconsin, a wildlife biologist was allowed by a court to let his backyard flourish in "native vegetation."

Park Service officials in Rock Creek are now bracing the public for the sight of unkempt lawns soon to appear during the growing season.

Stay calm, is the message. Nature is at work even if the mowers are not. The purpose of this free growth goes beyond the visual beauty to be exhibited by a variety of clovers, black-eyed Susan, Queen Anne's lace, heal-all, blue-curl, sweet everlasting, St. Johnswort, deptford pink, Knapweed and butter and eggs. It is expected that more meadowlarks, goldfinches ans indigo buntings will nest in the Rock Creek in the summer, and more field and tree sparrows in the winter. As Peggy Fleming, a park technician explains it, "Obviously there will be a variety of new flowers and plants. With the plants will come associated insects, moths and butterflies. With an increase of small mammals, hawks and owls.As the new growth is left standing over winter, nesting sites are available for rabbits and seeds are available for wintering birds."

Whatever the season, and however high the "weeds," the tall grass can only benefit the citizens who seek the beauty of Rock Creek Park. All small children should experience the pleasures of running bare-legged through the undulating meadows of high grass. For ourselves, we will be calling the Park Service from time to time to see how this full-growth program is going. The soft temperatures of the past few days suggest that nature is ready to cooperate. Some citizen cooperation is next.