What to Plant in August UK: 20 Crops to Sow Now

August is the most underrated sowing month in the UK. Warm soil and shortening days suit salads, oriental greens, spring cabbage and overwintering onions — sow now, harvest into spring.

Updated: 2026-08-06 13 min readBy Emma Greenfield

What to Plant in August UK: 20 Crops to Sow Now

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Quick Summary

August is the most underrated sowing month in the UK. Warm soil and shortening days suit salads, oriental greens, spring cabbage and overwintering onions — sow now, harvest into spring. August is the most underrated sowing month in the UK calendar. Warm soil and shortening days suit fast salads, overwintering onions, spring cabbage and green manures — and everything sown now crops when the shops are most expensive.

Why August Is a Better Sowing Month Than People Think

Most UK gardeners stop sowing in July and spend August harvesting. That's a mistake, and it's the single easiest way to double what a small plot produces in a year. Soil temperature peaks in August — seeds germinate in three or four days rather than the two weeks they take in April. Meanwhile, day length is dropping, which suits leafy crops that would bolt straight to seed if sown in May. The result is a window where salads, oriental greens, spring onions, turnips and overwintering brassicas all establish faster and more reliably than in spring. Sow in the first three weeks of August for autumn harvests, and the last week for crops that sit through winter and crop in the hungry gap next March and April. In a mild UK winter, a small covered bed sown now will keep a household in salad leaves from October to Christmas.

What to Sow in August (UK)

Salad leaves, rocket and mizuna — sow all month

Ready in 4–6 weeks. Sow every fortnight in a shady spot; August rocket is far less prone to flea beetle and bolting than the spring sowing.

Spinach and chard — sow first 3 weeks

Autumn spinach is sweeter than spring. Chard sown now stands right through winter and regrows in March.

Spring cabbage — sow first 2 weeks

Sow in modules, transplant in September at 30cm spacing, net against pigeons. Harvest as spring greens from March.

Pak choi and oriental greens — sow all month

The classic August crop. Shortening days stop them bolting. Ready in 6–8 weeks under a cloche.

Turnips and radish — sow first 3 weeks

Fast and reliable. Baby turnips ('Snowball', 'Purple Top Milan') are ready in six weeks.

Spring onions and overwintering onion sets — sow late August

Sow 'White Lisbon Winter Hardy' now for a March pull. Japanese onion sets go in from late August in the north, September in the south.

Coriander, dill and parsley — sow all month

August-sown coriander is the one that doesn't bolt. Grow in pots you can bring under cover in October.

Green manure — sow after clearing any bed

Field beans, phacelia or grazing rye. Free soil improvement over winter, dug in or chopped down in March.

What to Plant Out and Buy in August

✓ Strawberry runners and new strawberry plants — August planting gives a full crop next June
✓ Autumn-planting garlic (order now, plant October–November)
✓ Spring-flowering bulbs: daffodils and crocus can go in from late August
✓ Container-grown shrubs, hedging and perennials, while soil is warm enough for root growth
✓ Autumn onion sets in colder regions from the last week of August
✓ Winter salad plug plants if you missed the seed window

Other August Jobs Worth Doing

Prune summer-fruiting raspberries

Cut fruited canes to ground level, tie in this year's new canes for next summer's crop.

Stop tomato plants

Pinch out the growing tip two leaves above the fourth or fifth truss so existing fruit ripens before autumn.

Water pots properly

Containers need daily watering in August. Move them out of full afternoon sun to halve the workload.

Collect seed

Nigella, poppies, sweet peas and calendula are all ready. Dry seed heads indoors in paper bags.

Cut lavender back

Trim after flowering, into green growth only — never into old wood.

Deadhead relentlessly

Dahlias, roses and cosmos will flower into November if you keep removing spent blooms.

What Not to Sow in August

✗ Runner and French beans — not enough season left to crop
✗ Courgettes, pumpkins and squash — needs 12+ weeks of warmth they won't get
✗ Sweetcorn, tomatoes, peppers and aubergines — far too late outdoors in the UK
✗ Carrots for main crop — sowings after early August rarely size up
✗ New lawns from seed in the first half of the month if a dry spell is forecast — wait for September

Kit That Extends the Season

August sowings pay off most when you can shelter them from October onwards. A low polytunnel cloche or a set of horticultural fleece covers will keep salad, pak choi and spinach cropping six to eight weeks longer than open ground. Add fine insect mesh to keep pigeons and cabbage white butterflies off young brassicas — netting is the difference between spring greens and shredded stalks. A small cold frame or mini greenhouse is the next step up and covers seed raising for next spring too.

Shop Cloches, Fleece & Winter Salad Seed

Free UK Sowing Calendar

Want the whole year on one page? Download our free printable UK Sowing Calendar, with sow, plant and harvest windows for every major vegetable, month by month.

Download the Free UK Sowing Calendar (PDF)

Recommended Buying Guides

Looking for the right products? These guides have you covered:

Browse Seasonal on Amazon

"August is the month that separates gardens that crop for six months from gardens that crop for twelve. Every bed you clear in August should be resown within a week — either with a winter crop or a green manure."

— Emma Greenfield, Home Gardening Pedia

Frequently Asked Questions

What vegetables can I plant in August in the UK?

Salad leaves, rocket, spinach, chard, pak choi and oriental greens, turnips, radish, spring onions, spring cabbage, kohl rabi and fast herbs like coriander and dill. Late August is also the start of overwintering onion sets.

Is August too late to plant vegetables in the UK?

Not at all — it's too late for anything needing summer heat (beans, courgettes, sweetcorn, tomatoes), but perfect for leafy crops and overwintering vegetables. Soil is at its warmest, so germination is faster than in spring.

What can I sow in August for winter harvest?

Winter-hardy salad leaves, mizuna, land cress, chard, perpetual spinach, spring cabbage and overwintering onions. Cover them with a cloche or fleece from October to keep them cropping through the cold months.

Can I plant flowers in August in the UK?

Yes. Plant autumn bedding such as violas and pansies, sow hardy annuals like calendula and nigella for early flowering next year, and start putting in spring bulbs such as daffodils and crocus from late August.

Should I plant grass seed in August in the UK?

Mid-September is the safest window, but late August works if you can water daily. Soil is warm enough for fast germination — the risk is a dry spell scorching new seedlings.

What is a green manure and should I sow one in August?

A green manure is a fast-growing crop such as phacelia, field beans or grazing rye sown to cover bare soil over winter. It prevents nutrient leaching and weeds, and is dug in or chopped down in spring. August and September are the ideal sowing months.

Emma Greenfield

Garden Design Writer

Emma focuses on garden design, outdoor living, and seasonal growing. She writes practical guides that make gardening accessible to complete beginners.