Harvest date calculator

How the dates are worked out

A photoperiod plant keeps growing leaves for as long as it gets 18 or more hours of light a day. Switching the lights to 12 hours on and 12 off, the flip, starts flowering, and the flowering time a breeder quotes counts from that day. So the harvest date is germination, plus however long you veg, plus the flowering time.

Autoflowers ignore the light schedule and flower on their own after a few weeks, so their figure counts from seed. After the chop, buds hang to dry for 7 to 14 days, then cure in sealed jars. Two weeks of curing makes them smokeable; most growers give it four or more.

Growing outdoors? Photoperiods flip themselves as the nights lengthen after midsummer. Choose “Count from: Flip to 12/12” and enter the day the first white pistils show.

Working back from a deadline runs the same sum in reverse, planned on the slow end of the flowering time so a late finisher still makes it. If the germination date has already passed, the calculator tells you how much veg you can still fit in before the flip, or the soonest harvest you can get if there is none.

Where the flowering times come from

They are the figures seed banks list on their product pages, kept as a range when banks disagree. They are breeder claims, not grow tests: phenotype, light intensity and temperature all move the finish by a week or more. How we source strain records.

Strains sold only as autoflowers are left out of the lookup. Banks often quote those from seed rather than from the start of flowering, under the same label, and a calculator can't tell which one it was given.

Read the plant, not the calendar

The date tells you when to start looking. Under a jeweler's loupe the resin heads on the buds go from clear to cloudy to amber; most growers cut when they are mostly cloudy with a little amber. By then the pistils have mostly darkened and curled in. Cutting earlier tends to give a lighter, more energetic high; waiting for more amber gives a heavier one.