How to Grow and Care for Autumn Crocus

Autumn crocus (Colchicum autumnale) flowers or "naked ladies" debut in early fall. What's unique about this plant (and why they're called "naked") is they have no leaves when they bloom. The dormant bulb-like corms should be planted mid- to late-summer for fall blooms. This plant has a slow growth rate, sometimes taking years to germinate and flower, but is fairly low maintenance. It does well in a variety of soils and will benefit from good sun. Autumn crocuses are toxic to humans and animals.

Autumn Crocus Care

Autumn crocuses are low-maintenance garden plants. They don’t typically have serious pest or disease issues, and rabbits and deer tend to leave them alone. The flowers attract butterflies and bees. Here are the main care requirements for autumn crocuses.

• Plant in an area that receives full sun for a good part of the day.
• Ensure the corms are in a spot with sharp soil drainage, but do not allow the soil to dry out completely.
• Provide a small amount of moisture initially during the summer to trigger root growth and get the bulbs going.
• Do not water in the summer once established or when the plants are dormant.
  

Light

The autumn crocus needs at least a half-day of full sun during its foliage phase. Because this occurs in the spring, it’s OK to plant the autumn crocus under deciduous trees, as the trees won’t have leafed out yet. The flowers will grow fine with some shade. 

Soil

Autumn crocuses can grow well in sandy loam or rocky soil. Moreover, they can handle a slightly acidic to slightly alkaline soil pH. The critical factor is good soil drainage. 

Water

A moderate level of soil moisture is ideal for the autumn crocus. Soil that is too soggy can rot the plant, while soil that is too dry can desiccate the corm. Water weekly—about one inch per week—during the spring, reducing watering when the foliage dies. Increase water again when the flowers appear. 

Temperature and Humidity

There is a relatively narrow growing zone for the autumn crocus compared to other flowering bulbs. Neither frigid winters nor warm winters provide the right conditions for dormancy for the corms. Excessive humidity is not good since it can encourage botrytis, a fungal disease, but sunlight and good drainage can thwart this.

Fertilizer

The autumn crocus grows fine without additional fertilizer. If your soil is poor, you can add some bone meal to the soil mix at planting time.

Types of Autumn Crocus

There are many varieties of the autumn crocus, some include:

• 'Innocence': This plant features clear white blooms and likes partial shade.
• 'Waterlily': This variety sports double pink blooms.
• 'Disraeli': The checkered pink flowers on this variety make a fascinating addition to the fall garden.
• 'Autumn Queen': This type has violet blooms.
• 'Giant': This one features white and mauve blooms.

Pruning

As with all flowering bulbs, do not cut back the plant's foliage. Only prune away the foliage after it has turned yellow. Allow it to die back naturally.

Propagating Autumn Crocus

Autumn crocus can propagate by division or sowing seed. Your autumn crocus will naturally propagate by forming small corms on the main corm. You can take advantage of this by digging up the plant and removing the baby corms when the plant is dormant in the summer.

Divide corms every three or four years in the summertime once they begin to spread and get crowded in the same area. Having space between plants helps to ventilate plants and reduces the threat of fungal diseases that target overcrowded plants. Here's how to divide autumn crocus corms:

1. Choose a pot with ample drainage holes and potting mix if planting in a container,
2. Dig out each of the corms in the summer with a hand shovel or trowel. Try to dig straight down deep, at least 6 to 7 inches, to get underneath the growth. Lift the clump out gently. Avoid splitting the clump and potentially destroying the corm.
3. Knock the dirt off; the corms should tease apart easily.
4. Replant them immediately. Corms benefit from growing in a bulb or cold frame, but they're not necessary for planting success.
5. Plant them 6 inches apart at a depth of at least 3 to 6 inches. As the corms grow, they will enlarge to a point when they are ready to bloom, usually a couple of years.

How to Grow Autumn Crocus From Seed

Division is the best and fastest method for propagation, but you can also sow seeds outdoors in the fall. Autumn crocus seeds need a chill period to trigger germination. Cover the seeds with a scattering of soil on top (1/16 inch deep). Seed germination rates are low and slow. If the seeds eventually sprout, they may take one to two years.

Potting and Repotting Autumn Crocus

You can grow autumn crocuses in pots, but they might not return the next growing season. Use containers that have good drainage holes. Corms like to be planted deeply, so get a pot at least 12 to 16 inches deep. Every few years, thin the corms from a pot that becomes too crowded.

Pot them in mid- to late-summer using a standard potting mix, and water when the soil is dry. Place the plant in a sunny location and keep it evenly moist. Repot every few years when the corms become crowded.

Overwintering

For overwintering protection, if you have autumn crocus plants in containers, sink the containers in the ground to overwinter. Underground, the sides of the containers are protected from harsh winds and heating and thawing patterns that more often affect potted plants exposed to wild climate fluctuations, like mild winter days to extreme cold snaps.

Or, after the first hard freeze, you can also protect potted autumn crocus plants by placing the pot in a shed, an unheated garage, or a cool basement for winter.

If your plants are in the ground, mulch is excellent for keeping the water from evaporating from the soil and preventing weed growth. If you live in a cold weather region, leave the mulch on the ground throughout the winter to protect the corms from the cold. Remove the mulch in the spring.

Common Pests & Plant Diseases

Autumn crocuses can be a tricky species to grow outdoors because of their susceptibility to slug damage. They're rabbit resistant, but snails and slugs might attack the corms. Remove slugs and snails by hand or set traps to catch them. If you mulch your autumn crocus, remove the 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 deadly bait (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 with beer. The slugs and snails will drown each evening trying to drink the beer.

Autumn crocus corms are also susceptible to fungal infections. Fungal smut or fusarium fungal rot can infect and kill the corms. Keep the soil well-drained to prevent these diseases. Soggy conditions make corms vulnerable to fungal infection. Once it takes hold, the damage is hard to rebound from. Be proactive with well-draining soil and avoid overwatering.

Divide and move the corms every few years to avoid fungal diseases from cropping up. If you notice any rot or premature foliage blackening, cut off and destroy any affected plants to prevent damage to other plants. Dig up the corm to inspect it. If it's blackened and mushy, it has rotted. Check the other corms. Destroy the infected corms. If any corms are salvageable, replant them in a new site with fresh soil. Discard the old soil.

How to Get Autumn Crocus to Bloom

Bloom Months

Autumn crocus is a fall bloomer. It will show in the months of September, October and November.

How Long Does Autumn Crocus Bloom?

A single flower can last up to two weeks and sometimes three before naturally fading.

What Do Autumn Crocus Flowers Look and Smell Like?

Flower stems emerge from the ground during late summer to early fall and can grow up to 6 to 10 inches in height. Each stem produces a star-shaped flower that is colored in shades of lavender-pink to lilac-pink. These flowers bloom during fall and do not have any foliage, which is why they are also known as naked ladies. The blooms are said to have a neutral smell.

How to Encourage More Blooms

Keep in mind the autumn crocus takes patience when it comes to flowering. If your autumn crocus is not flowering and was originally grown from seed, it can take at least four years before flowers appear. Similarly, if you are expecting flowers from divided corms, it can take two years before the corms grow large enough underground to produce flowers.

Once you have reached this point, ensure your plant receives several hours of sun a day and the soil is well draining. Avoid clay soils, as these will hold moisture. You can also try adding bone meal or a high-phosphorous fertilizer in case nutrient-deficient soil is the problem.

Caring for Autumn Crocus After It Blooms

It's best to allow the flowers of the autumn crocus to naturally fade as the blooming season concludes. Also, allow the foliage to die back. This process will naturally feed the bulbs for the following season.

Deadheading Autumn Crocus Flowers

You don't need to deadhead your autumn crocuses as the flowers will fade naturally. They look dainty and pretty in small vases, so that you can pick them for a short indoor display. No matter how ratty the foliage looks in summer, leave all foliage in place until it has completely died back. The foliage is gathering energy and making food from its foliage and storing it in the corm for flower production in the fall. This process is completely necessary for flower production.

Common Problems With Autumn Crocus

Autumn crocuses do not have many problems; they are relatively easy to grow but require patience before you see germination or flower production.

Flowers Flop Over

Autumn crocuses prefer full sun. If you notice the flowers have emerged, but many of the flowers have flopped over, they could need more sun. Consider digging up the corms the following summer after the foliage has faded and relocating them to a full sun location.

Brown Spots On Leaves and Stems

Autumn crocuses are susceptible to late spring frosts. You might notice tiny brown spots that turn into larger blotches on the leaves that split or look ragged. Winter protection can help prevent this condition. Lay down a mulch layer over the corms after the first freeze.

Foliage Distorted or Stunted Growth

Insects and pests can make autumn crocuses look sickly, wilted, stunted, or yellowed if not unchecked. Bulb mites are minuscule and hard to see with the naked eye. They have four pairs of legs, piercing-sucking mouth parts, and very compact bodies. Below ground, hundreds of mites will feed on the corm pulp. Dig up and destroy any infested corms. You should soak other unaffected corms from the same soil in hot water (110 to 115 degrees Fahrenheit) for three hours.

Similarly, nematodes or worms will feed on underground corms using piercing, sucking mouthparts, hurting the root system, causing corm decay, and eventually killing the plant. Remove and destroy affected corms. To prevent nematodes from infesting your corms in the future, mix leaf mold with the soil when planting corms. Leaf mold encourages beneficial fungi that attack nematodes.