The National Park Service will curtail summer help and get a bit stingier with its lawn fertilizer, but recent federal budget cuts will not affect the operating hours at the Washington Monument or other park attractions in the nation's capital, a park service spokeswoman said yesterday.

Though spending cuts required by the Gramm-Rudman-Hollings law will take a $4 million bite out of the park service's $84 million regional operating budget, the public won't feel the effects in as dire a way as patrons of the Library of Congress, where reading room hours have has been sharply reduced.

"The Washington Monument will remain open its regular hours this summer," said Sandra Alley, a spokeswoman for the service's National Capital Region. "We're definitely not closing or shortening the hours for it or any of the other monuments."

The Washington Monument stays open until midnight during the summer.

If park visitors here notice any difference, she said, it will be that there aren't as many park rangers and other park service employes on hand to answer questions or give directions and other assistance. There will be a 20 percent reduction in the number of summer employes, which usually is about 250.

"There will be fewer rangers greeting more visitors," said Alley, noting that summer employes would probably be hired later than usual or let go earlier.

Also, she added, there will be reductions in the purchase of maintenance supplies, heavy equipment and other materials used to keep the region's 50,000 acres of federal parks shipshape.

Nationally, the park service is coping with an across-the-board cut of $39 million in its $793 million fiscal 1986 budget and will be taking similar steps to save money.

Alley said some 3,000 area volunteers, including many who offer visitor assistance at the Vietnam Veterans Memorial and Civil War battleground sites, will enable the park service to operate a regular schedule with its existing personnel.