Spinach
Spinacia oleracea
It bolts on day length as much as temperature, which is why spring spinach is always brief.

Day length, not just heat
Spinach bolts primarily in response to lengthening days, which is why a spring crop is always short no matter how cool the weather stays. Understanding this changes how you plan it: autumn and overwintered crops, sown as days shorten, produce for months instead of weeks.
Autumn is the real season
Sow from late August through September. The plants grow through the cool autumn and stand through winter. Spring spinach gets perhaps three weeks of picking before it runs to seed.
Overwintering is the best trick
Sown in September and covered with row fabric or a low tunnel, spinach survives a zone 6b/7 winter easily and restarts growth in February, giving the earliest and heaviest harvest of the year, well before anything else is ready.
It wants lime
Unusually among greens, spinach prefers near-neutral to slightly alkaline soil, pH 6.5-7.5. Acidic ground gives stunted yellow plants that never thrive. This is one crop worth liming for specifically.
Rich soil and steady water
A heavy nitrogen feeder for such a small plant. Work in compost, side-dress once or twice, and keep moisture steady - drought stress triggers bolting even in cool weather.
Leaf miners
The main pest: larvae tunnel between the leaf surfaces creating pale winding blotches that make leaves inedible. Row cover from sowing is the only really effective control. Remove and destroy mined leaves rather than composting them.
Downy mildew
Yellow patches on top with grey-purple fuzz underneath, favoured by cool humid weather - which is exactly spinach weather. Space for airflow, avoid overhead watering, and buy varieties with numbered downy mildew resistance, which is now standard.
Harvest and storage
Pick outer leaves individually for a long harvest, or cut the whole plant an inch above the crown for a second flush. Harvest in the morning. It keeps about a week in the fridge and freezes well blanched, though it collapses to very little.
- Days to harvest
- 35-50
- Spacing
- 3-6 in
- Row spacing
- 12-18 in
- Sun
- Full to part
- pH
- 6.5-7.5
- Hardy to
- ~15F
- Best season
- Fall and overwintered
- Bolt trigger
- Long days