A single sowing of cut flowers gives a flush of blooms, then quality and stem length fall away. Succession sowing, a new batch every few weeks, keeps fresh, long stems coming all season.
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Choose the date you want the first flowers and how long the variety takes from seed to bloom. The planner counts back to each sowing date, shows when every batch flowers and warns you if gaps would appear between batches.
batches = ceil(weeks of flowers ÷ sowing interval) first flowers of batch n = first bloom date + (n − 1) × interval sow date of batch n = first flowers of batch n − days to bloom batch n flowers until = first flowers + flowering weeks
Each batch is timed backwards from the day you want it in flower. If one batch stops flowering before the next begins, the planner warns you to sow more often.
Zinnias that take 75 days to flower, wanted from 1 July for 15 weeks with a sowing every 3 weeks, need 5 sowings: 17 April, 8 May, 29 May, 19 June and 10 July. The batches start flowering on 1 July, 22 July, 12 August, 2 September and 23 September.
Every 2–4 weeks from your first safe sowing date until about 10–12 weeks before your first autumn frost is a common approach.
Single-stem flowers such as sunflowers need sowing every 1–2 weeks. Cut-and-come-again flowers like zinnias and cosmos need fewer batches, but later sowings give longer, cleaner stems.
Seed packets and catalogues usually list days to maturity or days to flower. Add a week or two for cooler conditions or for transplants that need to settle in.
Yes. The planner only counts days between dates, so it works anywhere. Just choose first bloom dates that suit your own season.