WITH THE CRISP days of early autumn long gone and the chill dampness of winter upon us, what's a gardener to do for a plant fix? The craving for green, growing things doesn't go away just because the sun does. As we are cloaked in our darkest days of the year, our visceral need for flowers and leaves only intensifies.

I don't know about you, but my own garden is far from satisfying stripped down to bare bones and evergreens. There are treasures — tiny pink cyclamen and swelling Camellia sasanqua buds. But such scattered incidents offer brief comfort.

It's time to hit the conservatories, where you can take pleasure in the sound of rain on glass roofs while cocooned in a restorative blast of heat and light, luxuriating in plants and more plants.

Both the Victorian glasshouse at Volunteer Park and the new Rutherford Conservatory at the Rhododendron Species Foundation offer an immersion into the vast world of plant species from warmer climes. Each is richly atmospheric. At the Volunteer Park Conservatory, century-old panes of glass protect people and plant collections alike, for an effect of time-tripping as well as continent-hopping. Every few minutes a big puff of fog engulfs the interior of the Rutherford Conservatory. It's only the passive cooling system, but the mist so effectively creates the feel of a tropical rain forest that you leave the Weyerhaeuser campus and Federal Way far behind.

Until I made the trek to see the new conservatory recently, I had no idea that a full third of rhododendrons, 300 different kinds, are native to the tropics. The 5,000-square-foot conservatory allows the foundation to fulfill its mission to conserve all rhodies, not just the hardy ones.

Now rhododendrons unlike any you've seen before are growing happily under glass along with exotic companion plantings such as orchids, bananas and tree ferns. A rushing stream, basalt boulders, a bridge, paths and benches, along with the temperature, turn this science lesson of a greenhouse into an idyllic spot to spend a winter afternoon.

What a vast assortment of rhododendrons the world offers up. Some have huge leaves like magnolias or feathery, euphorbia-like foliage. Others have white tubular flowers that look and smell like giant jasmine blooms. Native to Borneo, Indonesia, the Philippines and New Guinea, many of these vireyas (tropical rhodies) are threatened or even extinct in the wild. But here in our climate, under glass, they'll be happily budding up and blooming throughout fall and winter.

"We have seven species of big-leafs in here," says nursery manager Dennis Bottemiller. Most of the plants were put in the ground just a year ago, and these giants of the rhody world will grow up to form a canopy beneath the glass. Caution: Don't even think about planting vireyas at home. Even though we live in rhododendron country, these plants won't reliably survive our winters unprotected.

Which is also true for most of the showy cactuses, succulents, orchids, tropical ferns and palms at the Volunteer Park Conservatory, which celebrates its 100th anniversary next year. The vast family of euphorbia, which bloom during the darkest days of the year, are featured throughout the conservatory in December. A display of Chinese mums has been replaced with the annual holiday extravaganza in the Seasonal House. "This year is a 1950s theme," says senior gardener David Helgeson. "Retro ornaments and those big colored lights."

Valerie Easton is a Seattle freelance writer and author of "The New Low-Maintenance Garden." Check out her blog at www.valeaston.com.