Spinach Growing Calendar: Four Sowings Through the Year

Four sowings, four different problems

Spinach is sown at four points in the year, and each has its own characteristic failure. Spring is a race against bolting, summer against germination, autumn is the straightforward one, and an overwintering sowing is about getting the plant to the right size before the cold.

Sowing	Sow	Harvest	Variety to choose
Spring	Early to late spring	Late spring to early summer	Bolt resistant
Summer	Midsummer	Early to mid autumn	Heat tolerant, mildew resistant
Autumn	Early to mid autumn	Late autumn to early winter	A standard autumn variety
Overwintering	Mid to late autumn	Late winter to early spring	Hardy types

The sowing window printed on the packet differs by variety. Spring and autumn varieties are effectively different crops.

The window moves with your climate

Read the timings against your own frost dates rather than against a calendar month. In a cold garden the spring sowing moves later and the autumn one earlier, and overwintering may not be practical at all.

Climate	Spring	Autumn	Overwintering
Cold	Mid spring to early summer	Late summer to early autumn	Under snow, or not viable
Average	Early to late spring	Early to late autumn	Sow in mid to late autumn
Mild	Late winter to mid spring	Early autumn to early winter	Late autumn sowing for a late winter crop

Inland and high ground behaves like a colder climate even in the same district. Working back from your average first frost keeps you closer.

The spring sowing is a race against bolting

Spinach bolts as the days lengthen and it warms. The aim is to have cut the crop before that happens, so the answer is a bolt resistant variety and a bias towards picking early rather than growing large.

Stage	Jobs	How to judge
Early spring	Sow a bolt resistant variety under row cover	Sow once the soil is above 50F (10C)
Mid spring	Two thinnings and one feed, ventilate the cover	Two inches apart at four true leaves
Late spring	Cut early, before the days lengthen further	Cut at nine to ten inches tall

With a spring sowing, cutting early beats growing large. Waiting another ten days is what loses the whole crop to bolting.

Summer: the months you can and cannot sow

In the hottest weeks the soil is too warm to germinate. Rather than fighting it, use the gap to prepare the bed, and start again once the nights cool.

Stage	Jobs	Watch out for
Early summer	Do not sow. Rest the bed and prepare it	This is the month for lime and compost
Midsummer	If you want a summer crop, chit and sow in the evening	Soil is warm and germination falls
Late summer	Prepare for the autumn sowing, get shade ready	Mildew and pests are at their peak

Autumn is the main season

The autumn sowing is the reliable one, so this is where to sow if you only sow once. Split it into two or three sowings ten days apart so the harvest does not all arrive at once.

Stage	Jobs	How to judge
Early autumn	The main sowing, in two or three goes	Once days are below 86F (30C)
Mid autumn	Two thinnings and feeding, check for damage	Picking starts at four to six weeks
Late autumn	Peak picking, finish sowing for overwintering	Overwintering plants want four or five true leaves

To spread the harvest, stagger the sowing dates rather than trying to do it with varieties.

Winter, and sweetening in the cold

Overwintering plants go into the cold with four or five true leaves and grow again in late winter. Exposing them deliberately to cold late in the season concentrates the sugars, which is what makes winter spinach worth growing.

Stage	Jobs	Watch out for
Early winter	Row cover or a cloche, last feed early in the month	Overwinter at four or five true leaves
Midwinter	Start cold exposure, open the cover by day	Aim for soil around 41 to 46F (5 to 8C)
Late winter	Open fully for two or three weeks, then cut	Cut on a dry morning once the leaves crinkle

Even where the tops are damaged, an overwintering plant with a live center grows again. Do not pull them straight after a hard freeze.

Written byYasuGrowing vegetables and fruit in Chiba, Japan, and building Gadenin. Corrections are welcome. 15 years of growing.