Saffron is a delicious and colorful seasoning that is used in breads, desserts, and main dishes in many parts of the world, from England to India, from the Middle East to Scandinavia, and all around the Mediterranean. Without it, an Indian curry or a Spanish paella just wouldn't be the same.
The bright red-orange threads you get when you buy saffron are actually the stigmas, or female portion, of the Saffron Crocus flowers. It takes hundreds of flowers to produce a commercially useful amount, which explains why saffron is so expensive. For the home gardener, however, two dozen Saffron Crocus will supply enough of the precious spice in the first year for a few memorable dishes. Then, with each successive year, the corms (which look like bulbs) will multiply, the size of the planting will increase, and you'll be able to harvest more of the spicy stigmas. After 4 to 6 years, you should divide and replant the corms (do it right after the foliage has faded). Division prevents overcrowding, which can lead to a decrease in flowering.
Planting Saffron Crocus Corms: In areas where Saffron Crocus are reliably hardy—USDA Zone 6 through 8 in the South, 6 through 9 in the West—you should plant the corms as soon as you receive them. Saffron Crocus do best in full sun and well-drained soil that is moderately rich in organic matter. Ideally, the site should be relatively dry in summer, when the corms are dormant.
Plant the corms 4in deep and 4in apart. If gophers, mice, or voles are a problem in your garden, plant the corms in containers or line the bed with hardware cloth or a similar wire mesh. Flowers generally come up 6-8 weeks after planting, although occasionally they wait until the 2nd fall to appear. Bloom lasts about 3 weeks. The grass-like leaves may emerge either with the flowers or soon after they appear. Sometimes they wait until the following spring. In either case, the leaves persist for 8-12 weeks, then wither and vanish, leaving no trace of the corms below until the flowers appear again in fall. It's not a bad idea to mark the area where you've planted your corms, so you don't inadvertently dig them up while planting something else.
Overwintering Corms in Cold Climates: Saffron Crocus can be grown in areas with colder winters than Zone 6, but the corms must be lifted and brought indoors for the winter. After the first few frosts, but before the ground has frozen solid, carefully dig out the corms, place them in a wooden crate or plastic tub, and completely cover with dry peat moss or sand. Store in a cool (40-50°F), dry place, such as a basement. Plant them out again in the spring after all danger of frost has passed, but don't water until you see new growth in early autumn.
Another way of growing Saffron Crocus in cold-winter areas is to plant the corms 2 in. deep in clay or plastic pots filled with a well-drained soil mix, and then set the pots directly in the ground, with the rims about 2 inches below the soil surface, so the pots don't show. After the plants die back in the fall, move the pots into the basement and store them dry for the winter. Set the pots back out the following spring. Again, marking the pots' location so you don't accidentally dig into them is probably a good idea.
Harvesting and Using Saffron: Three stigmas are borne in the center of each purple, cup-shaped bloom. The best time to harvest the stigmas is mid-morning on a sunny day when the flowers have fully opened and are still fresh. Carefully pluck the stigmas from the flowers with your fingers, then dry them in a warm place to preserve them for cooking. Store in a closed container. To use saffron, steep the threads in hot liquid (water, broth, or milk, depending on the recipe) for about 20 minutes. Add both the threads and the steeping liquid early in the cooking or baking process, and the threads will continue to release their color and flavor.