In fact, New York is surprisingly green. Nearly 20 percent of the city is public park land, a figure that earned it second place this summer, behind San Diego, when the Trust for Public Land conducted its annual Park Score survey of the 50 largest cities in the United States.

That’s a lot of park, and the inventory is more varied than many New Yorkers realize. The superstars hog the headlines: Central Park, Madison Square, the botanical gardens in Brooklyn and the Bronx. At sidewalk level, jaded urban eyes scale down their expectations to the window box overflowing with geraniums, the tub of flowers outside a restaurant, the caged-in plantings clinging for dear life to the trunks of trees.

However, the city teems with unsung small parks and gardens midway on the scale between flower pot and Great Lawn. Some are squeezed in discreet niches between buildings. Others are new and await discovery. Still others have undergone a metamorphosis.

I have had my eye on a number of these gems, and the waning days of summer — the lull between last bloom and first frost — gave me an excuse to put together an eclectic tour. Several of the choices come from the 52 community gardens that the New York Restoration Project has owned and managed since 1999, most of them known only to neighborhood residents. I zeroed in on the handful that stand out for their landscaping and design. I also included two gardens in the city’s parks system, the Bosque and the Gardens of Remembrance. These sanctuaries, developed between 2001 and 2005, have been hiding in plain sight at the Battery, largely ignored by the throngs heading to the Statue of Liberty, Ellis Island and Governors Island.

The Gil Hodges Community Garden in Gowanus, Brooklyn, one of those owned by the Restoration Project, has been around for more than 30 years, but it has just undergone a makeover, with money from the city’s Department of Environmental Protection and from Jo Malone, a British fragrance company. The transformed version opens on Wednesday.

On a plot of around 3,000 square feet, Yvi McEvilly, the Restoration Project’s director of design, has packed in a maximum of plant activity. Up front, a fragrance garden sends out the aromas of calycanthus, daphne and other species chosen for both nose and eye appeal. A wandering series of steppingstones, recycled shards of concrete from the old garden, leads past raised herb and vegetable beds to a birch reading grove.

The garden incorporates several environmentally friendly features. A large section of it relies on rainwater collected in an underground reservoir, rather than city water. On two sidewalks, five rectangular tree beds have been enhanced with native plants like ironweed and winterberry. One is now a bioswale: a giant sponge that takes in rainwater diverted from the street and lets it soak into a subterranean chamber, thereby relieving pressure on the sewer system.

Small can be thrilling. It can also be elusive. The city-owned Lentol Garden in Greenpoint, Brooklyn, a sliver of green pressed right up against the entrance ramp to the Brooklyn Queens Expressway, offers a glimpse of enchantment. Through iron gates, passers-by can feast their eyes on plump hydrangea blooms, purple and ivory butterfly bushes and a magnificent Chinese dogwood, now displaying clusters of raspberrylike fruit.

Getting inside the gates is another matter, unless you are one of the high school students working on summer programs in environmental science administered by the local Y.M.C.A. and New York University.

The Restoration Project’s community gardens, on the other hand, must be open to the public 20 hours a week. Sometimes the hours are posted, sometimes not, and the local organizations that operate the gardens day to day do not always keep to the schedule. I never did manage to penetrate Maggie’s Garden, a seductive, beautifully landscaped enclave on 149th Street near Broadway, in Hamilton Heights.

Even when the gardens keep to their hours, it can feel like a stroke of luck when the gates are open. On a recent weekend, Greg Dava, a Brooklyn resident taking a shortcut to the A train at High Street, walked into the Bridge Plaza Community Garden, near the borough’s downtown area, with a look of astonishment on his face. “This is the first time I’ve ever been inside,” he said. “I’ve only seen it through the gates.”

What he saw was one of the jewels in the community-garden system. Hardly bigger than a postage stamp, it somehow manages to accommodate evergreen trees and shrubs, a Japanese maple, hydrangeas and roses, brick and flagstone walkways, and a lily pond stocked with koi.

A hexagonal wooden bench encircles the garden’s ornamental cherry tree. Off in one corner is a pole with brightly colored birdhouses stacked atop one another, adding a cheery note.

There are others like it, scattered far and wide. Curtis Jackson, the rapper known as 50 Cent, financed a renovation of a community garden in Jamaica, Queens, his old neighborhood. Now named the Curtis “50 Cent” Jackson Community Garden, it opened in 2008.

Six deep-blue metal rainwater collectors, 10 feet tall with a dish on top, stand guard over a neat complex of pathways and raised beds with marigolds, sunflowers and vegetables. A pergola entwined with shade-giving trumpet vines runs the length of the garden along 165th Street.

About 10 blocks away, the Linden Boulevard Community Garden offers a moody contrast, with twisting, moss-covered brick paths that squiggle their way under towering shade trees and past ornamental shrubs like rhododendrons, cherry laurels and Japanese hollies. The colors of spring and summer have faded, but the garden, designed by the parks department veteran Edie Kean, still casts a spell in green.