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Growing spinach

Sowing in the cool halves of the year, why spinach bolts, and the soil pH it quietly insists on.

Quick facts

Spacing between plants
4 in (10 cm)
Spacing between rows
12 in (30 cm)
Plants per square foot
9 per square9 per square, square foot gardening method
Sun
4+ hours a day
Water
1 in a week (25 mm)
Soil pH
6.5 to 7.5
Days to maturity
37 to 50 days
Yield per plant
0.3 to 0.6 lb (0.14 kg to 0.27 kg)
Start seeds indoors
Not usually started indoors — it goes in as soon as the ground can be worked, weeks before anything needs a windowsill.
Transplant out
Not transplanted — sow where it will grow.
Direct sow
5 weeks before last frost

Square foot gardening figures come from Mel Bartholomew’s method and assume an intensive bed of amended soil. Spacing-derived figures assume conventional rows.

Scientific name: Spinacia oleracea. Spacing and planting dates checked against University of Illinois Extension. Yields, days to maturity and companion lists were never systematically checked — see how this data is checked.

Work it out for your garden

How many spinach plants fit in your bed?

96 plants — 4 rows of 24, at 4 in apart with 12 in between rows.

The spacing divides evenly into both dimensions, so the bed is fully used. Try staggered rows

Sowing dates for spinach

Enter your frost date for spinach sowing dates, or use the full planting date calculator for a whole season.

What will you harvest?

1.8–3.6 lb over the season, from 0.3–0.6 lb per plant. Add other crops

This page has the numbers for spinach: 4 inches between plants with 12 inches between rows, nine to a square foot, direct sown six weeks before your last frost, an inch of water a week, and a third to two thirds of a pound per plant in 37 to 50 days.

Two figures here are unusual and both are covered below. Six weeks before the last frost is earlier than almost anything else, because spinach germinates in cold soil that would rot other seed. And the pH range of 6.5 to 7.5 is higher than most vegetables want — spinach in acid soil stays small and pale however well it is fed.

When to sow

Direct sow about six weeks before your last frost date — spinach germinates in cold soil that most seed would rot in, and the seedlings take frost without harm. Sow again every two weeks until about three weeks after the frost date, then stop.

Start again in late summer, roughly eight weeks before your first fall frost, for an autumn crop. In many climates a late sowing will overwinter under fleece or a cold frame and produce a heavy crop the following spring, which is often the best spinach of the year.

What does not work is sowing through midsummer. Lengthening days trigger flowering regardless of temperature, and a plant that bolts turns bitter within days.

Soil and pH

Spinach is fussier about pH than most vegetables. It wants near-neutral soil, roughly 6.5 to 7.5, and in acid ground it stays small and pale however well you feed it. If a bed grows everything else well but produces poor spinach, test the pH before changing anything else.

It also wants nitrogen, being entirely leaf. Compost worked in before sowing, and a light feed once the plants are established, suits it.

Spacing

Four inches between plants with 12 inches between rows, or nine to a square foot. Thin early; crowded spinach makes small plants that bolt sooner.

Sow half an inch deep and keep the surface damp until the seedlings appear, which takes a week or so in cool soil.

Water

An inch a week, consistently. Spinach is shallow rooted and mostly water, so it registers a dry spell within days — and drought stress is one of the things that triggers bolting, alongside day length.

Water the soil rather than the leaves. As well as reducing leaf spot, it keeps soil out of the crinkles, which is where gritty spinach comes from. Mulching does the same job.

Harvesting

Take outer leaves and leave the centre growing. A row picked this way will give several harvests over a few weeks. Alternatively cut the whole plant an inch above the crown and many varieties will produce a second, smaller flush.

Pick in the morning while the leaves are turgid. Spinach wilts fast once cut in the heat of the day.

Once a plant starts to stretch upward and the leaves become pointed rather than rounded, it is bolting. Harvest everything worth having immediately and clear the row — there is no way back.

Common trouble

Leaf miners tunnel pale blotches between the leaf surfaces. Remove affected leaves; a fine mesh over the row prevents the flies laying in the first place.

Downy mildew shows as yellow patches on top with grey fuzz beneath, in cool damp weather. Space generously and avoid working among wet plants.

Bolting is the main thing that ends a crop, and it is a calendar problem rather than a cultivation one.

Growing alongside spinach

Good neighbours

Strawberry, Radish, Pea, Cabbage

Keep apart from

Nothing in particular — this one is easy-going.

Watch out for

  • Bolting once days lengthen
  • Leaf miners
  • Downy mildew

Companion planting pairings are traditional garden practice rather than settled science. Spacing, sun and water do far more for a crop than its neighbours do.

Spinach questions

Why does my spinach bolt so fast?
Day length as much as heat. Spinach is triggered into flowering by lengthening days, which is why a spring sowing can bolt while the weather is still cool. The fix is timing rather than care: sow early in spring and again from late summer, and skip the middle of the year. Varieties described as slow to bolt buy a couple of weeks, not a season.
Why are my spinach leaves small and yellowish?
Often soil pH. Spinach wants a near-neutral soil, around 6.5 to 7.5, and struggles in acid ground more visibly than most vegetables — pale, stunted plants that never bulk up. A soil test is worth doing before blaming feeding. Nitrogen shortage produces similar yellowing, but from the older leaves first.
Is spinach the same as chard or New Zealand spinach?
No, though they are used similarly. Chard is a beet relative and tolerates heat far better, so it carries on through summer when spinach has bolted. New Zealand spinach is unrelated again and also heat tolerant. Growing true spinach in the cool halves of the year and one of the others through summer gives leaves all season.
Can spinach survive winter?
In many climates, yes, and it is one of the best uses of a cold frame or a length of fleece. Sown in late summer, spinach grows slowly through autumn, sits out the cold, and then produces a heavy early crop as soon as days lengthen. Overwintered spinach is usually the best of the year.
How do I harvest spinach so it keeps producing?
Take the outer leaves and leave the growing point in the centre. The plant carries on producing from the middle for several cuttings. Cutting the whole plant an inch above the crown often gives a second flush, but the outer-leaf method gives a longer harvest from the same row.
Why is my spinach gritty?
Soil splashed onto crinkled leaves during watering or rain, which hides in the folds. Mulching the bed stops most of it, and watering the soil rather than over the top of the plants stops the rest. Savoy-leaved varieties hold more grit than the flatter-leaved ones.

Other crop guides

Calculators for this crop

Last updated

Written by Muzamil Ali. The figures in the quick-facts table are typical published ranges that have not yet been checked against a primary source, so treat them as a starting point and defer to your local extension service. See the disclaimer and how these pages are made.