How to Grow Spinach from Seed (Spinacia oleracea)

Spinach has a reputation it does not deserve. Ask a gardener why they gave up on it and the answer is almost always the same: it ran to seed before they got more than one decent picking. That is not bad luck and it is not poor soil — it is a plant doing precisely what it was built to do. Spinacia oleracea is a long-day plant, which means it is triggered into flowering by lengthening days rather than by heat, so a crop sown in early summer is being told to bolt from the moment it germinates. Sow it when the days are getting shorter and the same plant becomes one of the easiest and most generous crops in the garden. Which is why the last week of August and the first three weeks of September are the best sowing window of the entire year.

• Sow Late Feb–mid Apr · mid-Aug–late Sept · avoid May–July
• Soil Rich, moisture-retentive and firm · pH 6.5–7.5
• Spacing Thin to 7–10 cm · rows 30 cm apart
• Harvest Baby leaf from 5 weeks · full leaves 8–10 weeks

Why spinach bolts — and why late summer is the easy season

Above roughly thirteen hours of daylight, spinach stops investing in leaves and starts building a flower spike. Heat, dry roots and overcrowding all speed that process up, but they do not cause it. This is why a June sowing fails no matter how carefully it is watered: at midsummer the plant is receiving sixteen hours of the one signal that ends its useful life, and nothing you do in the bed can argue with that.

Turn the calendar round and the same biology works entirely in your favour. A sowing made in the next three weeks germinates into shortening days and cooling soil, so the bolting signal never arrives at all. The plants grow steadily into November, sit out the dark weeks without complaint, and then produce their heaviest cut in March — weeks before a spring sowing has made its first true leaf. Our September sowing guide and the seeds to sow in September collection cover what should go in alongside it, and succession sowing explains how to keep the picking continuous rather than feast-and-famine.

Choosing a variety: prickly seed, round seed and modern F1s

Old European seed catalogues split spinach into two groups by the shape of the seed, and that split still tells you what a variety is for. Prickly-seeded types — the Dutch scherpzaad, sold as Breedblad Scherpzaad or Broad Leaf — were selected as autumn and winter crops: slower, tougher and thicker in the leaf. Round-seeded types were the spring and summer group, faster and more tender but far quicker to run up. (The prickles, incidentally, are not on the seed at all: what we sow is a small dry fruit with the true seed inside it.)

For a sowing made now, choose an overwintering variety. Winterreuzen — literally winter giant — and Amsterdams Reuzenblad are the classic hardy broad-leaved types, and both come through frost that flattens a summer variety. Keep Bazaroet and other summer selections for a February sowing instead. Modern F1s such as Rembrandt, Red Kitten and Colusa buy you something different again: numbered resistances to the races of downy mildew, which is the disease that ends most autumn spinach crops early. Browse the whole range in our spinach seed collection, by species under Spinacia oleracea, or in organic spinach.

How to sow spinach, step by step

1. Feed the bed before you sow, not after Spinach is a nitrogen-hungry leaf crop on a short timetable. Work in compost or well-rotted manure a fortnight ahead — see preparing your soil and feeding and fertilising.
2. Sow direct, 2 cm deep, and resist transplanting Spinach makes a taproot and sulks — or bolts — if it is moved once it is past the seedling stage. Direct sowing is the reliable route; modules only work if planted out at two true leaves.
3. Cool the drill if the soil is still warm Spinach seed goes dormant above about 25 °C. In a warm late-August week, water the drill with cold water an hour before sowing, sow in the evening, and shade the row with a board or fleece until the seedlings appear. See why seeds are not germinating.
4. Thin early and thin twice First to 4 cm, then to 7–10 cm once the plants touch. Crowded spinach bolts first and mildews worst, and the thinnings are the best salad you will eat all week.
5. Keep the water steady — never let it check A single dry spell is enough to trigger bolting in a young plant. Water deeply twice a week rather than daily sprinkles; our guide to watering the garden explains the difference.

True spinach and its warm-season stand-ins

Grow both and you never have a gap. True spinach handles the two cool ends of the year; perpetual spinach and chard — botanically Beta vulgaris, a beetroot rather than a spinach — carry you through June and July, and New Zealand spinach thrives in exactly the hot, dry conditions that finish the real thing off. Round the bed out with kale, pak choi, mustard greens, corn salad, rocket and a quick row of radish, and if the weather beats you altogether, microgreens on a windowsill give you leaves in ten days.

Common spinach mistakes

• Sowing in June — the commonest mistake of all, and the one no amount of watering can fix. Sow before mid-May or after mid-August.
• Sowing into hot soil — above 25 °C the seed simply refuses. If the row is bare after ten days, it is the soil temperature, not the seed.
• Leaving it thick — unthinned spinach is a mildew nursery and bolts weeks early. Be ruthless, and eat the thinnings.
• Feeding hard in October — a late nitrogen feed produces soft growth that neither survives frost nor tastes good. Feed in spring, when the plants restart.
• Cutting out the crown — take outer leaves and leave the growing point, or cut the whole plant 3–4 cm above the crown so it can regrow. Cut lower and that is the end of it.
• Ignoring downy mildew — yellow blotches with grey felt underneath spread fast in still, damp autumn air. Space widely, water the soil not the leaves, and see common plant diseases.

Frequently asked questions

Why is my spinach flowering when it is only 15 cm tall?
Because of the calendar rather than anything you did. Once the flower spike is up the leaves turn bitter and thin, and there is no way back — pick everything usable that day and resow. If it is late August, you can have a replacement crop germinating within the week.

Can I really grow spinach right through winter?
Yes, with a hardy variety sown by about the middle of September. Growth stops below ten hours of daylight, so think of it as storing a mature plant alive in the ground rather than growing it. A cloche or fleece from late October keeps the leaves clean and speeds the March restart — see cloches, fleece and cold frames. It pairs naturally with a row of winter lettuce sown at the same time.

How do I pick spinach so it keeps producing?
Take the outer leaves and never more than about a third of the plant at once, working round the row rather than stripping one plant. Handled that way a single autumn sowing gives four or five pickings before Christmas and a heavy final cut in spring. Our guide to harvesting and storing produce covers keeping the leaves fresh afterwards.

Will spinach grow in pots or in a shady bed?
Both, and shade is an advantage in the warmer months — spinach is one of the few crops that genuinely prefers it. Use a deep, wide container that will not dry out; see growing from seed in pots and what to grow in shade for working out how much sun a spot actually gets.

Spinach only asks you to sow it at the right time; everything after that is watering and picking. Put a row in this week, thin it hard in three, and you will be cutting leaves in October, again after Christmas under a cover, and heavily in March. Fill the rest of the bed from our vegetable seeds or the organic range, follow the basics in our beginner's vegetable guide, and while the beds are being filled it is worth remembering that autumn is also the one moment when perennials sown from seed get their cold treatment for free. The rest of our growing guides will keep you busy until the light comes back.