Autumn Crocus (Colchicum autumnale) - How to Grow & Care Guide

Plant Snapshot

Common Name: Autumn Crocus
Latin Name: Colchicum autumnale
Hardiness Zones: USDA zones 4–8. In colder zones plants die back to corm and may need deeper planting or mulch. In warmer zones flowering can be reduced and poorly drained winters increase rot risk.
Typical Height: About 6–12 in (15–30 cm) to top of flowers.
Typical Spread: Clumps often 4–8 in (10–20 cm) across for individual plantings. Will naturalize slowly.
Bloom Period: Blooms in autumn. Typical months reported as September to October in the Northern Hemisphere and March to April in the Southern Hemisphere.
Soil Preferences: Prefers fertile, well drained soil. Tolerates heavier soils if not waterlogged. Poor drainage leads to corm rot. Generally tolerant of neutral to slightly alkaline pH.
Light Preferences: Full sun to part shade. Afternoon shade can help where summers are hot.
Toxicity: All parts are poisonous if ingested due to colchicine. Toxic to humans and pets and can cause severe gastrointestinal and organ effects. Use gloves when handling and keep away from children and animals.
Propagation: Mainly by dividing corms after foliage has died back. Can be grown from seed but seedlings take several years to flower.

Key Facts

A bulbous perennial that produces crocuslike flowers in autumn.
Flowers usually appear without accompanying foliage.
Leaves emerge in spring and die back before flowering.
Contains the alkaloid colchicine and is highly toxic if ingested.
Prefers well drained soil and can rot in poorly drained ground.
Suitable for naturalizing in lawns and under trees where drainage is good.
Propagated mainly by dividing corms after leaf dieback.
Flowers are typically pink to lilac in garden selections.

Autumn Crocus is a bulbous perennial that produces crocuslike flowers in autumn, prized for late season color but highly toxic if ingested. Leaves emerge in spring and die back before the autumn blooms.

Identification

Flowers are crocuslike and typically pink to lilac in garden selections. Plants reach about 6 to 12 inches tall to the top of the flowers. Blooms usually appear without accompanying foliage.

Best uses and where to grow

Use Autumn Crocus to naturalize under trees and in lawns where drainage is good. It performs in full sun to part shade and afternoon shade helps in hot summers. Reported hardiness is USDA zones 4 to 8 so confirm local conditions for extremes of cold or heat.

Soil light and watering

Prefers fertile well drained soil and tolerates neutral to slightly alkaline pH. Poor drainage leads to corm rot so avoid waterlogged sites and improve drainage or plant on a slight rise in heavy soils.

Planting and propagation

Plants form small clumps often 4 to 8 inches across so allow that spacing when planting to naturalize. Propagate mainly by dividing corms after foliage has died back in spring. Seed raised plants are possible but seedlings take several years to reach flowering size.

After flowering care

Flowers appear after the foliage has died back so avoid disturbing the ground in autumn. Leave corms undisturbed and lift only for division after the spring foliage has finished and withered.

Controlling spread

Autumn Crocus naturalizes slowly over years. Divide corms every few years to maintain vigour and to control spread in mixed plantings.

Toxicity and handling

All parts are poisonous due to the alkaloid colchicine and can cause severe effects if ingested. Wear gloves when handling and keep plants away from children and pets. For any exposure contact local poison control or emergency services and verify species identification.

Frequently asked questions

How fast does Autumn Crocus grow?: It spreads slowly and naturalizes over several years. Seedlings take multiple years before they flower.
Is Autumn Crocus poisonous?: Yes. All parts are poisonous because they contain colchicine. Keep away from children and pets and use gloves when handling.
When does Autumn Crocus bloom?: Blooms in autumn. In the Northern Hemisphere typical months reported are September to October but timing varies with latitude and microclimate.
How tall does Autumn Crocus get?: About 6 to 12 inches to the top of the flowers.
How do I propagate Autumn Crocus?: Divide corms after the foliage dies back in spring. Seed is possible but takes years to produce flowering plants.
Can I naturalize it in a lawn?: Yes where drainage is good and mowing is timed so bulbs are not damaged. Avoid sites that stay waterlogged in winter.