The sign standing outside Keeping It Green Nursery in Stanwood rings of an oxymoron.

Hardy orchids, it says.

Aren’t orchids supposed to be delicate flowers, the type of bloom that needs as much attention as a toddler?

Yes and no. Tropical orchids can’t thrive outdoors in Washington’s sometimes-frigid climate. This far north, they need the controlled heat of a greenhouse. But dozens of other orchid species — hardy orchids — crave a cold spell. They need a few months of near-freezing temperatures to develop.

Arlen Hill, owner of Keeping It Green Nursery, sells several varieties of hardy orchids, some of which are native to Washington state or come from similar climates, like China.

“It’s kind of funny, because they’re not necessarily that good looking — they’re just sort of odd,” Hill said of the yellow and pink flowers, which often don’t look like a stereotypical orchid. “I guess the main reason I like them is just the fact I can have them outside.”

There are about 40 species of orchids native to Washington, according to the Washington Native Orchid Society. Hill sells about 20. Prices for a single plant at his nursery range from roughly $8 to $70 — often less than tropical orchids.

“Usually what happens is you start growing your tropical orchids and then you get into the hardies,” Melissa Rathbun-Holstein, founder of the native orchid society, said. “I think that’s how it usually progresses. Arlen went the other way.”

Hill, a 25-year-old who wears Quiksilver shirts and an eyebrow ring, majored in photojournalism at Western Washington University.

He grew attached to flowers, however, during hikes in the San Juan Islands and the Cascades. The bright colors and odd shapes made the orchids pop out of their surroundings. Some had slipperlike petals with one big bloom. Others had dozens of tiny purple bell-shaped flowers. And all were terrestrial, capable of growing outdoors with little care.

“It seems like, why not grow them?” Hill said of his decision to start a nursery. “You can just stick them outside and let the natural temperature and rain and light take care of it.”

Well, almost.

The orchids can’t be planted into an average Snohomish County back yard without some prep work. The flowers do best in conditions with even moisture in the summer and consistent drainage. Also, to avoid the clay in local gardens, Hill recommends making a raised bed — a patch of fertile soil laid on top of the earth.

Rathbun-Holstein said gardeners can start with the hardy Chinese orchids, also known as bletillas.

“Those are the easiest to grow outdoors,” she said. “You really don’t have to fuss with them. They can take any kind of pH in the soil. You just want to make sure it’s got good drainage.”

Along with orchids, Hill grows woodland species and other plants native to the Northwest. He recently bought two acres of land near his retail nursery to help expand his operations. Eventually, he may become a wholesaler.

He started his nursery when he was 21. Still a one-man show four years later, the retail nursery rests on about 600 square feet in Stanwood. Often Hill goes to garden shows or spends his time outdoors, cultivating his many plants.

“I hate being inside for too long,” he said. “I like being outside and just getting in the dirt.”

And, of course, so do his orchids.

Reporter Andy Rathbun: 425-339-3455 or e-mail arathbun@heraldnet.com.

Growing interest

Melissa Rathbun-Holstein of the Washington Native Orchid Society recommends different varieties of hardy orchids.

Hardy Chinese orchids: Beginning gardeners can start with these flowers, which need less attention but still require good drainage. “You need to get the bed ready before you get them,” she said. “Otherwise, you’re just wasting your money.”

Stream orchids: Intermediate gardeners might want to plant these flowers, native to Washington state. Stream orchids grow in conditions similar to hardy Chinese orchids, but need a better garden bed and more consistent drainage.

Bog orchids: Expert gardeners can take a crack at these flowers, many of which grow along the waters’ edge in Florida. During Washington winters, they need to be put in pots that can be left outdoors. In the spring and summer, they go into a bog system, such as a pond liner.