The Bellevue Botanical Garden Perennial Border originally stretched 300 feet by 90 feet along a sunny hillside. It has now been enlarged to cascade down the hillside.

To dally with dahlias . . .

A curvaceous planting bed filled with 40 rows of dahlias stretches along the lawn across from the Conservatory at Volunteer Park. Volunteers from the Puget Sound Dahlia Association plant the tubers in May and dig them up for winter storage at the end of October. The pink dahlia in the foreground is 'Figurine.'

Visit Volunteer Park any time from mid-July to first frost and stroll south across the lawn from the Conservatory to find a plentiful display of dahlias planted and maintained by the Puget Sound Dahlia Association.

This club thinks big: Every May members plant hundreds of dahlia tubers, then weed, stake, label and fertilize them during the growing season, and dig them up again at the end of the October. In between the bursts of summer dahlias, the large, semicircular planting bed is home to hundreds of spring-flowering bulbs, a rotation gardeners can emulate at home, as bulbous plants all enjoy similar conditions (full sun and good drainage), so do well sharing a space.

Forty rows of dahlias fill the wide curving bed, their colors glowing against a green backdrop of mature rhododendron and dogwood. The dahlia growers aim for a well-balanced display that shows off all the different forms of dahlias and the full range of colors. Here you'll find plenty of the original daisy-types, as well as the newer anemone dahlias with tubular petals arranged in the shape of a well-stuffed pincushion. By mid-August, if you are brave enough to wade in between all the stakes, you'll be fully surrounded by fat flowers in glorious colors, including the huge fluffy yellow `Brassy,' the miniature scarlet balls of `Rothesay Superb' and the dinner-plate-sized, softly mauve `Emory Paul.'

How does the club keep all these dahlias looking so plumped up and healthy? It helps that we rarely have extreme heat or humidity, so our area is a prime one for dahlia growing. And the steps to perfect dahlias are simple. They must not be watered when first planted, as it is easy to drown a tuber. Wait until the dahlia starts to grow before watering. They must be protected from slugs when they first emerge from the soil, and all dahlias need at least a half-day of sunshine but prefer a full day's worth (don't we all?).

A pergola defines a transition between plantings of perennials, like the golden rudbeckia at its base, and the more formal rose garden beyond.

You'll want that notepad as you surround yourself with dahlias so you can write down names of your favorites. Most dahlias in the display garden will be available for purchase in April at the Puget Sound Dahlia Association's annual sale. Each January, club members donate dahlia tubers from their own gardens. The tubers are carefully sorted and checked out for quality and health. In April, 400 to 600 different varieties go on sale just in time for early May planting. If the sight of hundreds of dahlias in full bloom inspires you, call the dahlia folks at 425-836-4487 for information about the upcoming spring sale.

If a border is in order . . .

Our corner of the world enjoys a hugely complex and justifiably world-famous perennial border, and though it is located in a botanical garden, it is unlike any other planting you might encounter in a suburban park. It is also unlike most botanical-garden plantings, which tend toward collections of plants arranged by family or geographic zone.

The Bellevue Botanical Garden's Perennial Border is an inspired mixing of garden plants in waves of color pyrotechnics. You can absorb an entire education on plant choice, border design and color artistry through frequent, year-round visits.

Nine years ago, the border was created by members of the Northwest Perennial Alliance, who have continued to maintain and expand it, an impressive accomplishment for any volunteer organization. Originally a hillside swathe 300 feet long and 90 feet across, the border has been expanded to include both a steep border area and a shady one. Plantings include trees, shrubs, vines, groundcovers, bulbs, grasses and roses, as well as perennials, a collection of plants mingling and mixing just as in the best home gardens.

Foliage, color, texture, bloom, scent - all are here in an expertly orchestrated explosion of plantings. You'll find old and familiar plants, plus very new plants brought back from England and planted before they are available in the United States, all arranged in combinations you'll wish you had thought of yourself (and will no doubt rush home to try).

I most enjoy visiting the border early and late in the gardening season. The border eschews our ubiquitous evergreens, so in winter a structure of evergreen ferns and old roses splayed upon metal trellising is shown off. At their feet hellebores open, tulips emerge and primroses are starting to bud up. In late summer, the many foliage plants peak in a crescendo of lushness, with rich color provided by crocosmia, daylilies, salvia, rudbeckia and the blooms of ornamental grasses. You can stand back on the lawn and admire the superb color play, or you can thread your way along the paths, nearly buried in beauty.

Beyond the locks . . .

Most of the dahlias on display in Volunteer Park, including this flashy red and white stripe, will be on sale next spring from the Puget Sound Dahlia Association.

The neatly radiating, layered scallops of orange 'Jamanda' are typical of ball-type dahlias, which may be a little easier to fit into home gardens than some of the dinner-plate-sized beauties in the display garden.

Cactus dahlias, like this yellow and pink 'Camano Messenger,' are among the largest blooms. Some reach 15 inches across.

One of the oldest Seattle park gardens is the Carl S. English Jr. Gardens at the Hiram M. Chittenden Locks. Many people come to the locks to marvel over the salmon leaping the ladders, or to watch the spectacle of the boat-filled locks filling and emptying. Visitors appreciate the shade of the venerable trees and picnicking on the grassy hillside.

But there is much more to admire.

When it built the locks to connect Puget Sound with our lakes, the Army Corps of Engineers set aside seven acres for a residence and landscaped grounds. The garden's waterside location provides some of the most moderate temperatures in Seattle, ideal for growing a wide range of plants.

Carl English, a horticulturist with the corps, tended the garden for more than 40 years (beginning in 1931), with the goal of creating a garden for both pleasure and serious study. Most of the older trees at the locks are grown from seed English collected in exchanges with individuals and arboreta around the world.

This tradition of seeking out the new and unusual continues, and it was here that I first saw Brugmansia grown large enough that I could walk beneath its bell-shaped flowers for a full hit of fragrance. Marginally hardy plants thrive alongside the saltwater, and palms, Eucalyptus, Ceanothus and Cistus grow large in the sheltered gardens. Even the flowering shrubs alongside the restrooms are special, as are the rose garden, the fuchsia collection and the carefully tended perennial beds.

If you visit, try to take your eyes off the bobbing boats and remember you are in a most unusual garden, filled with an expertly chosen and carefully tended array of ornamental plants collected from around the world.

Valerie Easton is a horticultural librarian and writes about plants and gardens for Pacific Northwest magazine. She is co-author of "Artists and Their Gardens," due next month from Sasquatch Books. Her e-mail address is vjeaston@aol.com.