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.