Autumn Crocuses: Planting Tips for Fall Blooms

There are many options to decorate your garden with flowers. A beautiful garden can bring out your personality in many ways. For this, you can definitely choose autumn crocuses and colchicums.
Although they look like spring flowers, I’m delighted to see the flowers of colchicums and autumn crocuses blooming in my garden every fall.

In my garden, the first colchicum flowers come up in late summer, a sure sign that fall is near. They’re soon followed by another fall flower, the autumn crocus. It looks a lot like the crocuses we see in the spring, but without the leaves.

I love seeing both pop up, although their arrival is another sign winter is coming. With mostly purplish to pink blooms, they stand out in my garden, especially among the colors of fallen leaves. Confused about whether autumn crocuses are right for your garden? Ahead, we discuss why they’re worth planting, how to care for colchicums, common problems to watch for, and much more.

Why Choose Autumn Crocuses for Your Garden?

Autumn crocuses (aka fall-blooming crocuses), with the botanical name Crocus speciosus, are native to areas of Turkey, Crimea and northern Iran. They’re mostly hardy in Zones 5 through 9.

Autumn crocuses can be a great option in your garden. There are several reasons to consider them. These perennial plants generally bloom in late autumn. You will find that these flowers can add vibrant color to your garden, while others fade away. According to Susan Mahr, Statewide Master Gardener Program Coordinator at the University of Wisconsin-Madison, “The word crocus usually conjures images of cheerful small flowers emerging from snow and ice as the first harbinger of spring.”

Colchicums are often called autumn crocuses, but they’re a different flower. Most for sale are native to parts of Europe and carry the botanical name Colchicum autumnale. They’re mostly hardy in U.S. Department of Agriculture (USDA) Plant Hardiness Zones 4 through 8. The leaves remind me of hostas. They come up in spring and gradually die back by early summer. The flowers pop up in late summer and early fall. In my garden, in USDA Zone 6a, I often see the first colchicum flowers in late August and early September.

“In the U.S., the commonly called Autumn Crocus is not a true crocus at all but a species or hybrids of Colchicum, a group of fall-flowering bulbs in the lily family (Lilaceae). Other common names for autumn crocus include meadow saffron, naked lady and colchicum,” says Mahr.

Types of crocuses and colchicum

There are several varieties of autumn crocuses and colchicums available. You can easily get the best fall-flowering bulbs. A few to consider include:

• Colchicum ‘Waterlily’: Has double the number of petals, making it look like a water lily flower.
• Colchicum ‘Giant’: Larger flowers and can grow up to 10 inches tall.
• Colchicum ‘Album’: White flowers.
• Crocus speciosus ‘Albus’: White flowers with a yellow center.
• Crocus speciosus ‘Oxonian’: Darker purple flowers.
• Crocus speciosus ‘Conqueror’: Bluer flowers.

One other fall-blooming crocus to consider: the saffron crocus, Crocus sativus. The red threads, the stigma part of the flower, are the expensive spice saffron.

How To Plant and Care for Colchicums This Fall

Both autumn crocuses and colchicums grow from corms.

• Plant the corms as soon as you receive them—they’re usually shipped in late summer.

Planting depth matters:

• Colchicum corms are larger and should be planted about 6 inches deep.
• Crocus corms go about 3 inches deep.

Fall blooming:

• Both often bloom in the same fall they’re planted.

Low maintenance:

• Once planted, they don’t need much care.
• Avoid overwatering, as it can cause the corms to rot.

Natural spreading:

• Over time, they’ll multiply underground, spreading from the original planting spot.

Dividing and replanting:

• Dig up and divide the clumps when the foliage begins to die back.
  This is the best time to see their locations and move or share them.

What to do with divided corms:

• Replant some in the same spot.
• Spread others around your garden or share them with friends.

Many of my favorite colchicums came from friends who generously shared them with me.

Troubleshooting Common Autumn Crocus Issues

Autumn crocus (Colchicum autumnale) is known for its delicate flowers. However, you can face several challenges with this plant. It contains colchicine, which is a potent alkaloid. It can be toxic to humans, livestock and pets if ingested.

• A few pests, such as bulb mites and nematodes, can damage your crocus corms. These pests will stunt the growth of your plants, so you should buy healthy corms.
• You should place a barrier around your crocus plants. This will prevent your pets and children from eating them.

Note: Always buy the corms from a reputable seller and watch them closely while buying them.

Designing a Seasonal Garden with Autumn Crocuses

Autumn crocuses produce foliage in the spring. They die back in early summer. Also, you will see leafless flowers in the fall. You need to incorporate these plants strategically in your garden.

• These plants thrive in full sun to partial shade. So plant them accordingly.
• Choose well-drained soil and a proper drainage system. It is best to place them near the edge of a border.
• Alternatively, you can plant them in a rock garden or groups in the grass. These designs will effectively showcase their blooms.

FAQ

How do you plant autumn crocus bulbs?

You should plant autumn crocus bulbs as soon as you buy them. The best time would be late summer. First, choose a sunny area in your garden or wherever you want to plant them. Always use well-drained and rich soil. Also, you need a well-functioning drainage system. Plant the corms about 3 inches deep. Also, plant them 3 to 4 inches apart. Avoid overhead watering. Excessive watering can harm your trees.

Are colchicum flowers poisonous?

Colchicum flowers are poisonous. Various studies show that they contain colchicine. It is a powerful alkaloid. If you eat these flowers, they can harm your body. You should always wear gloves when handling the bulbs. Keep these plants away from pets and children.

How much sun do autumn crocuses need?

If you can provide full sun or partial shade, it will be best for your autumn crocuses. These plants benefit from full sunlight, especially in the spring. Their foliage emerges at that time. Autumn crocuses can also tolerate light shade in the fall.

What’s the difference between autumn crocuses and spring crocuses?

There are some differences between autumn crocuses and spring crocuses. Autumn crocuses bloom in the fall. But you will see that spring crocuses bloom in early spring. Maybe they have similar appearances. But many autumn crocuses are actually colchicums. They are not true crocuses. They belong to a different plant family.

Expert:

• Susan Mahr, Statewide Master Gardener Program Coordinator at University of Wisconsin-Madison

Sources:

• Taylor & Francis Online: “Accidental poisoning with autumn crocus (Colchicum autumnale): a case series”
• ScienceDirect: “Colchicum autumnale L.”
• Missouri Botanical Garden: “Colchicum autumnale ‘Pleniflorum’”
• RHS: “Autumn-flowering crocus”
• ResearchGate: “Toxicity and Sublethal Effects of Autumn Crocus (Colchicum autumnale) Bulb Powder on Red Imported Fire Ants (Solenopsis invicta)”
• NLM: “Case report: fatal poisoning with Colchicum autumnale”
• ResearchGate: “Autumn crocus – A conflict species for agriculture and nature conservation? [Die herbstzeitlose – Eine problempflanze für landwirtschaft und naturschutz?]” 
• ResearchGate: “Fitochemical and Antioxidant Characterization of Autumn Crocus (Colchicum Autumnale) Flowers and Roots Plant Extracts”
• ResearchGate: “Colchicum autumnale: A review”
• NLM: “Acaricidal Activity of Colchicum autumnale (autumn crocus) Extract against Hyalomma spp. In vitro”
• University of Wisconsin-Madison: “Autumn Crocus, Colchicum spp.”