Fast-flowering seeds for a short summer.

Filters we used, and why

• Feminized: every seed grows into a female plant, the one that flowers, so you don't need to spot and remove males. Feminized or regular.
• Photoperiod: it flowers when the nights get longer, so outdoors it grows all summer and flowers in autumn. Autoflower or photoperiod.
• Flowering time short: under 56 days of flowering, as the breeder or a shop states it. Grow specs.

Why flowering time decides an outdoor harvest in the north

A photoperiod plant starts flowering when the nights get longer, in most of Europe and Canada from late July into August. How long it then needs to finish decides whether you harvest in dry September weather or in the October rain.

Flowering time	Typical outdoor harvest in northern Europe	Risk
Short: under 56 days	Mid to late September	Lowest
Average: 56 to 77 days	Late September to mid October	Rain and cold nights
Long: 77 days or more	Late October or later	High: mould, frost

The exact dates depend on the strain, your latitude and the season. But the order holds: the shorter the flowering time, the more likely the buds finish dry. Grow specs.

Who this page is for

Growers outdoors where summer ends early: the UK and Ireland, the Netherlands and Belgium, north and central Germany, Scandinavia, Canada and the northern US. Also greenhouse growers who want to finish before heating costs rise.

Why not just grow an autoflower?

You can, and fast autoflowers finish in summer. A photoperiod grows all spring and summer before it flowers, so it gets much bigger and gives far more per plant. A fast-flowering photoperiod gives you that size and still finishes in time.

Mould: the risk that matters most

Grey mould (botrytis) thrives on dense, wet buds in cool weather. It can rot a plant from the inside in days. Besides choosing a short flowering time:

• Give the plant air. Space plants apart and thin out crowded inner branches.
• Let it dry after rain. A spot with wind and morning sun helps.
• Check the buds from mid September, and cut out any brown or grey parts right away.

Mould resistance isn't a filter yet. Look under More from the sources on each seed's page.

Indica, sativa and flowering time

Indica-leaning plants tend to flower faster and grow more compact; sativa-leaning ones often flower longer. If you want the safest bet for a northern summer, add mainly indica. Indica, sativa, hybrid.

When to start

Step	Typical timing in northern Europe
Sprout indoors	April to early May
Plant outside	After the last frost, mid to late May
Flowering starts	Late July to August
Harvest	September

Start too early and a photoperiod plant may try to flower in the short days of spring. Keep seedlings under long light indoors until the days outside are long enough.

Make it yours

• Add mainly indica: indicas tend to finish fastest.
• Fast autoflowers: no need to wait for autumn at all.

Good to know

Mould resistance isn't a filter yet. Look under More from the sources on each seed's page.

Filters like high, short, small and easy only show seeds where a breeder or shop states that figure. A seed with no figure sits in the middle bracket, so it isn't shown here even if it would fit. No figure? The middle bracket.