When to sow delphiniums in Renca

Why these dates

Plant out in spring after the last frost, or in early autumn where winters are mild. Stake early, before the spikes are half grown - a delphinium staked after it leans never straightens. Cut spent spikes to the base for a lighter second flowering in early autumn.

Hardy to -30C when dormant, but dislikes hot humid summers more than cold winters and is genuinely difficult above zone 7. Emerging shoots are a favourite of slugs and are checked by hard late frosts.

Seed packets and extension guides express timing as weeks either side of the last spring frost, because that is the only reference point that travels. Delphiniums are timed from 10 weeks before that frost for an indoor start, with planting out 2 weeks after it, and this page simply resolves those offsets against the frost date computed for Renca.

Renca sits in zone 9b, which is milder than this crop wants, and a winter that never really arrives is its own problem. The dates below still describe the right time of year; the open question is survival rather than timing.

Do not expect a crop in the first year. A plant set out now should give its first worthwhile pick around year 1, and will then produce every year after that, which is what makes the planting decision worth getting right the first time.

See every crop timed for Renca →