What to Plant in August in the UK: Your Last-Chance Sowing Guide

August is the last warm window before shorter days shut the season down. Here's exactly what to sow, plant, and get in the ground. Including what's still worth doing even if you're starting late.

Section 01

Salad Leaves: Fast Crops for Bowls All Autumn

Salad leaves are worth sowing all the way through August. The soil is still warm enough for fast germination, but the cooling temperatures ahead stop plants from bolting the way they do in June. Quick establishment, no bitterness, no racing to seed.

Sow cut-and-come-again varieties directly into a prepared bed or a deep container: mixed leaf, rocket, mizuna, lamb's lettuce. Scatter seed thinly. Rake in lightly. Water well. You can be picking within 4 to 6 weeks.

Succession sow every two weeks through August. Once October temperatures drop, cover with a cloche or fleece and plants will keep producing well into November and December. Little Gem and Iceberg handle light frosts without any cover.

If the weather turns wet before you've had a chance to sow outside, start seeds in modules on a windowsill in early August and transplant out once seedlings are established.

Key takeaway: August-sown salad leaves can keep producing right through autumn. Sow every two weeks and cover with fleece once temperatures drop.

Section 02

Spinach and Chard: The Cooler Weather Performers

August spinach outperforms May spinach. Spring sowings bolt: once temperatures rise, plants rush to seed before you've had a decent harvest. August sowings avoid that. Shorter days and cooling nights keep plants in leaf rather than pushing them into flower.

Sow 2.5 cm deep, rows 30 cm apart. Thin to 15cm once established. Ready to pick in 6 to 8 weeks. Cover with fleece in October and you can harvest into winter.

Swiss chard is tougher. It tolerates cold better than spinach and will stand through winter in most UK regions without protection. Sow now and you'll have a harvest running from October right through to next spring.

Key takeaway: Spinach sown in August won't bolt. Swiss chard sown now produces right through winter.

Section 03

Brassicas for Spring: Spring Cabbage, Kale, and Pak Choi

Some August sowings aren't about autumn at all. Spring cabbages sown now will sit through winter as small plants, then grow fast in March and April, delivering a harvest long before any spring sowing could. It's the only way to get cabbages in June without a heated glasshouse.

Sow in modules or a seedbed. Transplant to final positions in September, 30 to 45cm apart. They need very little through winter. Keep the area weed-free and net against pigeons if needed.

Kale survives hard frosts, takes baby leaf picking or full-size harvests, and needs almost no attention. Sow or transplant in August for picking from October right through to March.

Pak choi is the quick one. Four to six weeks from sowing to harvest. August sowings give you a crop in September and October, well before cold sets in. Direct sow and thin to 15cm.

Key takeaway: Spring cabbage sown in August overwinters and delivers in June. Kale sown now produces through the whole winter.

Section 04

Root Veg: What's Still Worth Sowing Now

August is the last realistic window for root vegetables. Fast-maturing varieties, in the ground early in the month.

French Breakfast and Cherry Belle radishes are ready in 3 to 4 weeks. Sow in short rows, succession sow fortnightly, and you'll have a supply into October.

Beetroot in early August still works. Detroit or Boltardy, 2.5cm deep, 10cm apart. Roots will be smaller than a summer crop. Still perfectly good by October.

Short-rooted carrots like Paris Market are viable in early August. Mid or late August: not enough time.

Spring onions are the reliable late option. White Lisbon direct sown now will be ready in October and November.

Key takeaway: Radishes and spring onions are the safe bets. Beetroot in early August is still viable. Carrots only if you're sowing short-rooted varieties early in the month.

Section 05

Herbs: Parsley, Coriander, and Chervil Before the Cold

Most herbs are past their window by August. Three aren't: parsley, coriander, chervil. They prefer cooler conditions, and this is genuinely the better time to sow them.

Coriander bolts in summer heat, which is why most gardeners give up on it. August sidesteps the whole problem. Sow in a pot or sheltered bed and cooler temperatures keep plants in leaf. Harvest from October through to the first hard frost.

Parsley is slow. Three to five weeks to germinate even in warm soil. Sow in August, grow on in a container, and move it under cover as autumn arrives. Parsley on a windowsill through winter is a genuinely useful thing.

Chervil germinates quickly, tolerates shade, and produces anise-flavoured leaves from autumn right into early spring. Direct sow in a sheltered spot, thin to 20cm, and leave it.

Key takeaway: Coriander, parsley, and chervil all do better from August sowings than summer ones. Move pot-grown parsley under cover in autumn, and it will keep producing through winter.

Section 06

Hardy Annual Flowers: Sow Now, Bloom in Spring

Hardy annuals sown in late August overwinter as small plants and flower months earlier the following spring than anything started in March.

Calendula, cornflowers, field poppies, nigella. Sow directly into a border or large container in the last two weeks of August. Scatter seed thinly, rake in, water, and mark the spot so you don't pull the seedlings when they come up.

Myosotis and Siberian wallflower are biennials. Sow now, and they'll flower in spring and early summer next year. Both come back freely from self-seeded plants once established.

Don't sow too early in August. You want established plants going into winter, not lush sappy growth that a hard frost will kill.

Key takeaway: Calendula, cornflower, and field poppy sown in late August will flower months earlier next spring than any March sowing.

Section 07

Autumn Bulbs: Colchicum, Crocus, and Early Daffodils

Don't wait for bulbs in August. Colchicum and autumn crocus arrive in garden centres from early in the month, already primed to flower. Leave them sitting too long and they'll flower in the bag before you've got them in the ground.

Colchicum goes in at 10 cm depth in well-drained soil. It naturalises well in grass and comes back every year. Autumn crocus at 8cm, in borders or lawn edges. Both flowers within 4 to 6 weeks of planting.

Daffodil bulbs start appearing in late August. Plant as soon as you can get them: roots need time to establish before the soil cools. Three times the bulb's own depth, usually 15 to 20cm deep, 10cm between bulbs.

Madonna lilies go in during August, not autumn. Just below the surface, about 2.5cm deep, in a sunny spot.

Key takeaway: Colchicum and autumn crocus need to go in as soon as you buy them. Daffodils planted in late August establish better than those left until October.

Section 08

Strawberry Runners and Fruit Jobs

Peg a strawberry runner into a small pot of compost set alongside the parent plant, and it will root within 3 to 4 weeks. Sever the runner once it's established. Do it now from your best producers and you'll have a full crop from those plants next summer.

Trained fruit trees need summer pruning in August. Cut new lateral growth back to 3 leaves from the base. Energy goes into the existing fruit rather than more foliage.

Outdoor tomatoes: remove any flowers that open in August. They won't ripen before the frosts. Better the plant puts its effort into what's already setting.

Key takeaway: Root strawberry runners from your best plants now. Each one is a free plant for next summer's crop.

Quick Reference

What to Plant in August: At a Glance

Expert Insight

Why August Sowings Often Outperform Spring Ones

Warm soil speeds germination in a way cold March soil can't. Seeds that take 2 to 3 weeks to come up in spring can germinate through the surface in days in August. That head start matters, even as the days shorten.

Pest pressure drops, too. Caterpillars, aphids, slugs: the worst of them are less active by late summer. Brassica seedlings establish with far less damage in August than plants put out in May.

The RHS counts over 30 million gardeners in the UK, with growing-your-own enquiries increasing year on year. Most of those gardeners will have beds to clear and space to fill this month. August is a better time to fill them than March.

Sources: RHS 2025 Gardening Predictions; RHS Monthly Advice: August

FAQ

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