Flower · Iridaceae
When to sow crocuses
Usually the first colour of the year, often flowering through the last of the snow. Cheap enough to plant by the hundred, which is the only way they look right.
Days to maturity
120-170
From sowing to a first picking.
Hardy in USDA zones
3a to 8a
Winter cold sets the limit here, not the calendar.
Frost tolerance
Very hardy
How much cold the plant itself will take.
Those weeks become real dates once you name a place.
Timing, in frost-relative terms
Crocuses are anchored to the first autumn frost rather than the last spring one, so the useful offset runs backwards from the end of the season instead of forwards from its start.
- Expect 120–170 days to maturity, counted from sowing.
- Hardy in USDA zones 3a–8a.
- Can also be sown in late summer for an autumn crop or to overwinter.
Getting the timing right
Plant in early autumn, six to eight weeks before the first frost, 8cm deep. Naturalising in grass is the best use of them: they flower and set seed before the first cut of the season is due, so the lawn can be left uncut until the leaves yellow in late spring.
Frost tolerance
Hardy to -30C and among the most frost-indifferent flowers grown - blooms freeze solid overnight and reopen the same morning. Needs a cold winter to flower well and fails in zone 9 and warmer.
Classified as very-hardy, with damage expected below -30°C (-22°F)-22°F (-30°C).