A mini saffron harvest: The prized spice comes from a fall-blooming crocus

When fall fogs start rolling in, it can be hard to hold on to the gardener's fantasy, nurtured through the summer by lavender festivals and the like, that the maritime Pacific Northwest resembles countries on the Mediterranean Sea. But you could extend this pleasant notion if you grow your own saffron.

Most saffron purchased here comes from Spain or India, and these twisted orange threads hold a prized reputation as the world's most expensive spice. Saffron's uses are as ancient as Crete and as exotic as the many languages from Sanskrit to Icelandic that have a word for it.

The prized flavoring and deep yellow dye comes from the stigma (female parts) of a crocus that blooms in fall rather than spring.

Here in the maritime Pacific Northwest, we can add the crocus to our own herb gardens and harvest an authentic, though minuscule, crop.

Just after Labor Day, local nurseries unpack tonnage of hardy spring-blooming bulbs. Ask some questions and you'll find, tucked into corners, small quantities of a few that are fall-bloomers.

Learning the botanical names of plants helps with precision, but in the case of saffron it's essential and more than an academic frill. The saffron crocus is botanically Crocus sativus (Sativus is the old Latin for any plant used medicinally or for cooking).

The crocus corm (the little unit you plant) resembles that of the spring-bloomers: It's firm, about the diameter of a thumbnail, and will often show the slightest white sprig on top where new shoots will emerge. But only the fall crocus yields the spice.

Warning: When purchasing bulbs, don't get saffron crocus confused with a plant that also blooms in fall and is called "autumn crocus," Colchicum autumnale — which is poisonous in all its parts. This one lolls around nurseries, often blooming on a shelf without soil. The bulb resembles an irregular fist, and the flowers are large, multipetaled, and white, purplish, or pink. Don't eat or harvest this one. (You'll often see it in gardens because it multiplies and persists well here.) If in doubt, get help with the identification before harvesting.

For centuries, people have experimented with growing saffron in cool climates including Switzerland, England and the Eastern United States. To thrive here, it needs dry, sunny summer conditions and good winter drainage.

One successful local grower used a raised bed facing south; these little crocus corms loathe wet feet. Soil doesn't need unusual amendments, it must simply drain well. Plant the corms in early September, about 4 inches deep, watering them in. The first year, a few deep lavender flowers will emerge in October, totally leafless.

To harvest, gather these flowers when they are fully expanded, looking just like a regular spring crocus. Pull out the scarlet stigma (three of them, immediately obvious when you remove the flower petals.)

Most professional growers apply some sort of heat to dry the stigmas. (Several sources suggested home food dehydrators.) However, they dry fine when simply laid on a paper towel, perfectly practical if your crop has 6 blooms rather than thousands.

To produce saffron year after year, let the leaves emerge and grow. They come after the flowers, resemble grass, and slowly grow longer and longer through the winter until they can be 18-24 inches long in spring.

They're floppy and funny looking during the spring when "normal" crocus are putting out flowers. Keep the plants watered during leaf growth. (This is easy, because their leaf growth coincides with our wet season.) Allow them to die back naturally, which will be about April. Keep the saffron crocus hiding underground dry throughout the summer. The second year, bloom will be heavier.

Then, like the Minoans, you're producing saffron.

Mary Robson is area horticulture agent for Washington State University/King County Cooperative Extension. She shares gardening tips every Wednesday. Her e-mail is gardeningtips@seattletimes.com.