When to Plant Crocus Bulbs

Crocuses are the cheapest optimism you can buy. A handful of corms planted on a grey autumn afternoon becomes the first real colour of the year — goblet flowers pushing through cold soil, sometimes through snow, weeks before the daffodils bother. The whole trick is timing, and the timing is now: autumn.

The short answer: September to November

Spring-flowering crocuses go into the ground in autumn, once summer heat has passed but before the ground freezes. In most temperate gardens that means September through November; October is the sweet spot in much of Europe and North America. The corms need those cool, moist weeks to grow roots, followed by a proper cold period — it's the winter chill that triggers flowering. Planted in spring, they simply sulk: no chill, no flowers.

One exception worth knowing: autumn-flowering crocuses (such as Crocus speciosus and the saffron crocus, Crocus sativus) are planted earlier, in late summer, and flower just weeks later the same autumn.

How to plant them

• Depth: 7–10 cm for the small early species (Crocus tommasinianus, C. chrysanthus), up to 12 cm for the fat Dutch hybrids. Rule of thumb: two to three times the height of the corm.
• Spacing: 5–8 cm apart. Crocuses look best crowded — plant in generous drifts of 20+, never in single-file rows.
• Orientation: pointed end up, flat basal plate down. If you truly can't tell, plant it on its side; the shoot will find its way.
• Site: full sun to light shade with sharp drainage. A waterlogged winter pot or bed rots corms faster than any pest.

Crocuses in the lawn

The classic look. Scatter corms by the handful and plant them where they land for a natural drift — a bulb planter or narrow trowel makes short work of it. Two rules make it succeed: choose vigorous naturalisers like Crocus tommasinianus or the Dutch hybrids, and don't mow in spring until the crocus foliage has yellowed and died back, usually about six weeks after flowering. Those leaves are next year's flowers refuelling the corm.

Crocuses in pots

Superb in shallow pans and the top layer of a bulb lasagne, above tulips and daffodils. Use gritty, free-draining compost, plant 7–10 cm deep, water once, and leave the pot somewhere cool and rain-sheltered for winter. You can also force crocuses for winter flowers indoors: keep potted corms cold (but frost-free and dark) for 8–10 weeks, then bring them into a cool bright room and they'll bloom weeks early.

Squirrels, mice and other thieves

Squirrels regard freshly planted crocus corms as a buffet. If they patrol your garden, lay chicken wire or metal mesh over the planting area (remove or lift it before shoots emerge in late winter), plant a little deeper, and firm the soil well — loose, freshly dug earth is an open invitation. Mice and voles tunnel to corms in beds; sharp grit in the planting hole helps deter them.

A warning: 'autumn crocus' isn't always a crocus

Warning: The plant sold as autumn crocus or naked ladies is often Colchicum autumnale — a lookalike from a different family, and seriously poisonous to people and pets. True autumn crocuses (Crocus speciosus, C. sativus) are the source of saffron; colchicums are not, and confusing them has caused real poisonings. Check the botanical name before you buy, and snap a photo with a plant identifier if you've inherited mystery bulbs.

After flowering

Deadhead nothing, dig nothing. Let the foliage die down naturally, and established clumps will bulk up by offsets (baby cormels) and even self-sow. Congested clumps that flower less can be lifted and divided as the leaves fade, then replanted immediately.

Inherited a bag of unlabelled bulbs, or unsure whether that clump is a crocus or a colchicum? Photograph it in PlantMe — the app identifies 35,000+ plant classes with 93% top-3 accuracy, so you know exactly what you're planting.