How To Grow Fall Flowering Crocus & Colchicum

Fall Flowering Crocuses are a fun late-season surprise in the garden. Most gardeners are familiar with spring-blooming Crocus. Fall Flowering Crocus, including Saffron and Colchicum, feature bright cup-shaped flowers at a time of year when many other blooms passed. These easy-to-grow bulbs add a layer of color to your garden or beneath trees or shrubs. Plant the bulbs when they arrive, and you'll have stunning jewel-like blooms in just a few weeks!

Light: Fall Flowering crocus bloom best in full sun. Without it, you'll see reduced flowering or floppy plants.

Soil: Fall Flowering Crocus grow best in well-drained, silty soil. Avoid heavy clay soils or those that drain water poorly. These will result in the bulbs (corms) rotting. Amend the soil with compost or sand, to improve water drainage. Or, consider planting in raised beds or containers. Fall Flowering Crocus like a neutral to slightly alkaline pH, so if you know your soil is acidic, add lime as needed.

Spacing: Space smaller Crocus and Saffron bulbs 3 inches apart, and larger Colchicum bulbs 6 to 10 inches apart. Plant the bulbs (corms) at a depth twice the diameter of the bulb;  For small fall crocus, this is about 3 to 4 inches, while colchicums can be planted up to 4 to 6 inches deep. They both look best if planted en masse.

Planting: Plant fall flowering crocus bulbs (corms) in late summer or early fall. After a late summer or early fall planting, fall flowering crocus should bloom in about 4 to 6 weeks depending on your climate. 

Planting In Containers: Small-flowered fall crocus can also be planted in containers. Plant in a container with good drainage holes filled with moistened potting soil. Place in a sunny location and keep evenly moist. After flowering, let the foliage emerge. In cold areas, protect the containers by bringing them into an unheated garage or basement for winter.

Growth Habit: 

Smaller crocus varieties have bulbs, plants, and flowers that are the same size as spring flowering crocus. They first send up flowers in early autumn, followed by grass-like leaves usually later in fall.

Larger-sized Colchicums bloom from September to November, depending on the variety. They send up large, goblet-like blooms up to 6 inches tall - without leaves. In spring, they send up broad leaves.

Staking: No staking is needed for low-growing Crocus and Colchicum.

Watering: Water Fall Flowering Crocus in late summer after planting only if the soil is dry. It's best to avoid watering while they're flowering. Keep the soil evenly moist after flowering until the ground freezes.

Fertilizing: Amend the soil at planting with compost. Adding bone meal or organic high-phosphorous fertilizer will encourage bulb growth and flowering. In a garden setting, add a 1- to 2- inch thick layer of compost and a small amount of a granular bulb fertilizer to the planting area each fall.

Mulching: In a garden setting, you can mulch Fall Flowering Crocus in late summer with a 1- to 2-inch thick layer of shredded bark mulch or chopped leaves. The mulch will conserve soil moisture, prevent weed growth and prevent the soil from splashing unto the delicate fall crocus flowers. Mulching is not recommended in areas with wet winters, to avoid bulb rot. In cold areas, leaving mulch on in fall and winter may help protect the bulbs from the cold.

Trimming & Pruning: Let the flowers naturally fade in autumn. Let the foliage in fall or in spring naturally yellow and die - the foliage rejuvenates the bulbs.

Dividing & Transplanting:

Both Colchicum and Crocus are very long-lived and benefit from dividing regularly. Fall Flowering Crocus bulbs will slowly multiply, and after 3 to 4 years they can be divided to produce more bulbs. Small bulblets (or cormlets) will form around the edge of the mother bulb.

• To divide, dig up the bulb clumps in summer while the bulb is dormant.
• Separate out the bulblets and replant in a location with similar growing conditions.
• The bulblets will take 1 to 2 years before they're large enough to flower. 

Pests/Disease: Fall Flowering Crocus and Colchicums do have some pests that like the bulbs and flowers as much as we do.

• Rabbits will munch on the flowers and foliage. A low fence and repellent sprays will keep them out.
• Mice and voles will tunnel in fall and winter and eat the underground bulbs (corms). When planting, add a small handful of crushed, sharp seashells, oyster shells, or egg shells to the hole. This will discourage them from tunneling to the bulbs.
• Slugs and snails will eat the foliage, especially in spring for the large flowering types. Remove any mulch away from the leaves in spring to reduce hiding places for the slugs. Place organic baits, such as iron phosphate, around the area. The slugs and snails are attracted to this bait, but once they eat it, the iron phosphate will kill them. It is safe for kids, pets and wildlife. You can also use beer traps. Sink a shallow bowl in the soil so the rim is at the soil line. Fill it 3/4th with beer. Each evening the slugs and snails will drown trying to drink the beer. Clean out the bowl each morning. Keep your dogs away from the beer trap because they might like to taste it too.
• Fungal rot diseases, such as fusarium, can attack the bulbs. Keep the soil well-drained to prevent these diseases. Dividing and moving the bulbs after 4 years of growing in one area will help avoid these diseases building up.

Saffron Crocus bulbs are a popular fall-blooming flower that brings an unexpected splash of color to your garden. Its red stigmas can be harvested for a delicious and highly-prized spice.

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