Crocus

About Crocus

Crocuses are small corms that open cup-shaped flowers in late winter or earliest spring, often right after the snow melts. They are among the first flowers of the year, and bees flock to them on cold days (UC Master Gardeners, Chicago Botanic Garden). Fall-blooming kinds include saffron crocus, whose red-orange threads are the spice.

NC State lists zones 3-8 (saffron crocus 5-8). In mild-winter California, chill corms about 10 weeks in the fridge and treat them as annuals (UC Master Gardeners); in South Carolina, snow crocus, Cloth of Gold and 'tommies' come back better than Dutch crocus (Clemson).

When to plant

Timing is counted from your average last spring frost (and first fall frost). Sow & Tell works out the actual dates for your ZIP code.

Plant spring crocus corms in fall about 3 inches deep (2 1/2-4 inches) and 2-4 inches apart (NC State, Clemson, Chicago Botanic Garden). Plant fall crocus and saffron crocus as soon as you buy them in late summer, saffron 4 inches deep and 4 inches apart (Clemson, NC State); lay chicken wire over new plantings to stop squirrels (UMN).

Soil

Well-drained, gritty sandy loam with some organic matter; avoid heavy clay (NC State).

Gritty, well-drained sandy loam with some organic matter; avoid heavy clay (NC State).

Feeding

• Early spring, as shoots come up (plantings you keep): balanced fertilizer such as 10-10-10. The general spring-bulb advice applies: Clemson gives 1-2 lb per 100 sq ft in fall and as shoots emerge. Follow a soil test.

Leave the leaves for about six weeks after bloom (NC State); if crocus grows in a lawn, hold off mowing that spot until then.

Harvest

Spring crocus blooms from February to March, and the flowers close at night and on cloudy days. Leave the leaves for about six weeks after bloom so the corms can recharge (NC State). Saffron crocus blooms for 1-2 weeks in fall: pick out the red-orange stigmas and use them fresh or dried (NC State).

Varieties (8)

Extension and botanical-garden sources we could open name 8 crocuses, several without descriptions; fall-blooming species other than saffron crocus are covered only in general terms (Clemson).

Pests to watch for

Tree squirrels, Voles, Rabbits

Diseases and problems

Root and crown rot

In the kitchen

Saffron, the costly spice, is the dried red-orange stigmas of saffron crocus (Crocus sativus), a fall bloomer (NC State).

Safety: Don't confuse crocus with autumn crocus or meadow saffron (Colchicum), a fall bloomer that looks similar and is poisonous (Clemson, ASPCA). Use saffron only from plants you know for sure are Crocus sativus.

Pets: Spring crocus can cause stomach upset (vomiting, diarrhea, drooling) in dogs and cats if any part is eaten (ASPCA). The look-alike autumn crocus (Colchicum) is far more dangerous: severe vomiting, bloody diarrhea and liver, kidney and possibly bone marrow damage (ASPCA).