Landing planes at Crissy Field in the Presidio of San Francisco is part of history and will remain that way, according to the Golden Gate National Recreation Area, which has spent $33 million to restore the grassy landing strip into something fit for any respectable biplane to touch down on.

That won't happen, said recreation area superintendent Brian O'Neill, who dropped by the landing strip to show off the greensward and the adjoining lagoon.

The landing strip, which is currently fenced off, will formally open on May 6 with an old-fashioned air show. The planes that take part in the air show celebrating the landing strip will have to take off and land someplace else, O'Neill said.

That's because the plush expanse of lawn is being reserved for "unstructured free play," O'Neill said. Games such as soccer and volleyball can be played informally but not formally. The park service will figure out exactly what that means by the time the fence comes down, a spokeswoman said.

On display at the landing strip will be a rare, restored DeHaviland DH4 single-engine plane of the sort that regularly took off and landed at Crissy Field during its glory days in the 1920s.

Don Gray, the director of the Crissy Field Aviation Museum Association, said he doesn't understand how the government can restore a landing strip and not allow even one single itty-bitty landing, for old times' sake.

"I guess they don't want any of the birds to be disturbed," Gray sighed. "God forbid we should hit one of them."

Restoring Crissy Field was a tricky business, O'Neill said. A World War II- era Army barracks had to be knocked down, even though it was historic, because it was sitting in the middle of the landing strip, which is 20 years' more historic than the barracks.

The Crissy Field restoration, which began in 1998, involves sprucing up 100 acres of Presidio land along the northern waterfront. Workers tore up the old road and restored the tidal marsh, which seven ducks were enjoying yesterday.

"We want to transform Crissy Field from the back door of the Presidio into the front door," O'Neill said.

To that end, park service gardeners have used color-coded stakes to plant 100,000 native plants, most of which have yet to bloom. Meanwhile, the yellow, white and blue stakes add a touch of color to the waterfront.

The Crissy Field project also includes a nature center, signs, picnic tables, benches, rest rooms and a snack bar that the park service is calling a "warming hut."

E-mail Steve Rubenstein at srubenstein@sfchronicle.com.

This article appeared on page A - 19 of the San Francisco Chronicle