Spring calls for a living carpet of blue-blooming corydalis

AFTER THIS winter of freezing and flooding, our early-spring gardens seem especially precious. So many plants have frozen or drowned since November, we'll be out there worshipping any plant brave enough to push up out of the soggy soil to bloom by the spring equinox.

Corydalis, with its early, sweetly spurred little flowers, is one of the first perennials to bloom. Grown in cottage gardens for hundreds of years, corydalis has long been a ho-hum perennial you wouldn't notice much. But the heavenly blue shades, discovered and propagated in the last decades, have made corydalis newly desirable. In 1989, three British plant explorers were enchanted by sheets of blue-blooming flowers they discovered in the woodlands of western China. Their sneaking out bits of corydalis rhizome in moss-lined film canisters has become horticultural legend.

From these few bits came the immensely popular azure cultivars, in shades from sky blue to gemlike turquoise. It all started with the charming C. flexuosa 'Blue Panda.' There's also 'China Blue' and 'Pere David,' and now 'Purple Leaf' with darker, more dramatic foliage.

You could plan an entire springtime garden scene around a mass of blue corydalis planted with daffodils, yellow, orange or pink primroses, and the fresh green of emerging fern fronds. For impact, plant corydalis in multiples because their short stature and small flowers can disappear into the landscape without plenty of like company.

Corydalis are woodland plants that grow lush and thick in light shade and rich, moist soil. Given these conditions, they spread to cover the ground with finely dissected ferny foliage. The bulbous kinds go dormant in summer, and they have a bad rap of not reappearing the following spring. In my own garden, I've too often forgotten about the corydalis down there in the soil all summer and dug them up or planted right over them. No wonder the poor plants give up. Any of the C. flexuosas are good for us forgetful types because if kept watered, their foliage persists through the summer as a pretty placeholder.

Two species of corydalis are native to the Northwest; C. scouleri grows into a mound of bright-green foliage sporting a generous measure of tiny lavender-pink flowers. The cream-flowering C. aquae-gelidea is rarer in cultivation; both grow wild in moist soils at lower elevations in the Cascade and Olympic mountain ranges.

Many gardeners remember the breathtaking mobs of corydalis swarming the woodland display garden at the old Heronswood nursery. So I checked in with Dan Hinkley, seeking wisdom from the guy who planted corydalis to such effect that it attracted horticultural pilgrims from around the world.

"I no longer garden in flexuosa territory," he says, referring to his new, sunnier garden, "but the C. flexuosas are really good and in sync with our climate." He offers this tip: Divide bulbous species like the pink C. solida just as they begin to go dormant in late May, and you'll have plenty of plants to spread about the garden. The lure of corydalis is so great that Hinkley is still searching for more of the brick red C. solida 'George Baker' he lost when Heronswood closed down. "It looks fantastic grown with black mondo grass," he says of these little woodland beauties. They're well worth the search.

Valerie Easton is a Seattle freelance writer. She blogs and answers questions at www.valeaston.com.