How do their gardens grow?

Fragrance, flowers or food.

That’s what landscape designer Kim Raftery was asked to provide from every plant included in the re-do of an Old Palo Alto landscape, one of six private gardens that can be seen on the 25th annual Gamble Garden Spring Tour April 23 and 24.

Most of the gardens have been previously featured on the annual tour, when they were newly planted. Now they’re being presented as either mature or redesigned and replanted.

The Lowell Avenue garden, which was featured in 2000, now surrounds a new home, which was built over several years. Many of the more mature plants were carefully protected, Raftery, owner of Raftery Garden Design, Palo Alto, said.

Although the owner is very fond of gardening, she wanted to make it simpler. This time, the garden was envisioned along with the architecture, which was completed in 2009.

Today, there’s a view of a different garden “room” from every window of the modern, Mediterranean-style home. From the library at the front of the house, one looks out upon a patio, framed by three 40-year-old Mission olive trees.

A new hedge near the front stucco fence will someday offer privacy; a loquat will soon be espaliered; and a new soapstone-and-marble fountain will provide sound.

One of the three mature agave plants recently sent up a 20-foot blossom on a stalk a once-in-its-lifetime occurrence — then died.

The goals of the redesign included sticking to the sight lines from the home, keeping a linear design (no curves here) and adapting low-water-use plants. No leaf blower removes fallen leaves; instead they’re incorporated for mulch.

“There used to be lawns. Now there are none,” Raftery said, pointing to gravel in the front, succulents in raised beds and groundcover by the pool made of four kinds of thyme and chamomile.

Beneath the herbs is a Netafim plastic-tubing drip system, with no water wasted through sprinkler evaporation, she added.

Near the entry to the garden is an old carob tree and ferns, with orange-blossomed Clivia tucked into the stainless-steel raised bed.

Along the perimeter of the garden are huge, old Podocarpus gracilior hedges that soar 20 feet tall. Raftery’s husband, arborist Kevin Raftery, prunes the hedges and trees at least twice a year.

Layered before them are rugosa roses, which Raftery calls “fragrant and tough,” and plenty of irises — both classic “flag” iris, with leaves like blades, and the native Pacific Coast hybrids, with more grass-like leaves.

Breaking up the linear design are a couple of jasper boulders, which were carted over from Hollister.

En route to the pool in the back, one passes a row of citrus trees, with lemons, limes, tangerines and Seville oranges, that one day “will provide privacy for the pool,” Raftery said.

All the beds are laid out with straight lines, so one passes a row of roses, followed by iris, then citrus, proceeding down poured-concrete paths.

Many of the original plantings survived the construction process, either protected by fencing or by living in pots. Those survivors include a Grecian laurel (Laurus nobelis), and pineapple guavas, with edible flowers that are “really sweet (and) taste like candy,” she said. Layered near them are three kinds of Daphne and the bell-like abutilon. Fruit trees — peach, apricot, plum and almond — line the back fence.

“The whole fence will be covered with espaliered fruit trees,” she said.

Looking out from the dining room and kitchen are the dining patio and vegetable garden. The mixed kitchen beds host a variety of herbs, including rosemary, cooking thyme, lemon verbena, marjoram and chives. Another bed has artichokes, potatoes and onions, while garlic, strawberries, tomatoes and basil thrive as well.

Because the western exposure gets quite hot, five fruit trees will create shade in the patio, which the built-in barbecue — topped in the same soapstone as the front fountain — anchors.

Ultimately a fragrant sarcococca bush will grow large enough to screen the air-conditioning unit at the front of the house.

Raftery says the large garden is actually easy to maintain because of its array of walkways and gravel. Maintenance, which includes sweeping with bamboo brooms, can be done in about three hours, once a week. Tree pruning is done twice a year, and the owner babies the roses and tends the vegetable garden herself.

Three of the private gardens on the Gamble Garden Spring Tour are clustered in Old Palo Alto, and three are in Crescent Park.

The other five “Masterful Gardens over 25 Years” are:

* a garden that reflects traditional materials and forms, with landscape design by Conger Moss Guillard, who designed the roof garden for the San Francisco Museum of Modern Art. The home, designed by architect Steven Ehrlich, was featured in Architectural Digest;

* a Mediterranean garden with an emphasis on water conservation, design and texture, succulents and roses, previously featured on the 1988 Spring Tour when it had green lawns and a backyard fireplace;

* a mature English cottage garden, where one steps through a yew archway to find roses, clematis, dogwoods, rhododendrons and camellias, as well as fresh fruits, vegetables and herbs; the garden was on tour five years ago as a young garden;

* a Country French garden — but with a California twist, with roses, perennials, fruit trees, lilacs, dogwoods and other shrubs; the garden was first on tour 25 years ago, when it was designed by Bill Derringer, then again 10 years ago, after updating by Katsy Swan;

* a lush English cottage garden that has evolved over decades, with a rose walkway, copper beech, a towering camellia grown from a 1-gallon can, roses that climb to second-story windows, wisteria wrapping around the back. This home was featured on tour in 1987.

Activities at Gamble Garden during the spring tour will include live music, a plant boutique and an “Over the Garden Fence” sale of used garden-related items, as well as sale of refreshments, box lunch (by advance reservation only), a raffle and a silent auction.

What:Gamble Garden’s 25th Annual Spring Tour

When:Friday and Saturday, April 23 and 24, 10 a.m. to 4 p.m.

Where:Six private gardens in Palo Alto and the Elizabeth F. Gamble Garden, 1431 Waverley St., Palo Alto

Tickets:Advance online tickets are $35 for nonmembers, $30 for members; same-day tickets are $40 at Gamble Garden; lunch tickets are $15 (and must be ordered by Friday, April 16).

Info:Call 650-329-1356 or visit www.gamblegarden.org.