📅 Succession Planting Schedule Calculator

Enter your available growing/harvest window, a crop's days to maturity, and your desired sowing interval to see how many succession plantings fit.

Harvest window (days)

Days to maturity

Sowing interval (days)

The last sowing has to finish inside the window

Maturity is taken off the front of the window first; whatever is left is the span in which a sowing can still be started:

usable  = harvest window - days to maturity
sowings = floor(usable / interval) + 1
days    = 0, interval, 2 × interval, ...

The defaults are a 90 day window, 45 days to maturity, sowing every 14 days. That leaves 45 usable days, floor(45 / 14) is 3, so four sowings go in on days 0, 14, 28 and 42. The last one matures on day 87, three days inside the window.

If maturity is longer than the window the count drops to zero and the tool prints "Window too short for this crop" instead of a list of dates.

Choosing the three numbers

The window is first safe sowing to last useful harvest, so it is bounded by your frost dates at both ends, or by the heat that ends a cool-season crop.
Check what maturity is counted from. Packets quote days from sowing for direct-sown crops but from transplant for others. If it is from transplant, add the weeks the plants spend in the tray.
Interval sets overlap, not total. A short interval gives more sowings and a steadier supply; a long one gives fewer and bigger gluts.

Days to maturity is a summer figure. Sowings made late in the window ripen more slowly as days shorten and soil cools, so the final one often runs past the day the arithmetic gives it.

Frequently asked questions

How many succession sowings fit in a 90 day window?

For a crop taking 45 days at a fortnightly interval, four - on days 0, 14, 28 and 42. Halve the interval to a week and you get seven.

Do days to maturity count from seed or from transplant?

It varies by crop and by seed company. Direct-sown crops are usually quoted from sowing, transplanted ones from planting out, so add the tray time before entering the figure.

Why does the calculator say my window is too short?

Days to maturity is longer than the harvest window, so even a sowing made on day one would not finish in time. Shorten the maturity by picking a faster variety, or lengthen the window.