August can be Onion Time – Sow Now for Next Year

🧅 August Means Onion Time – Sow Now for Summer Rewards
Just as you're admiring the onions you sowed back in spring and wondering when to pull them, it’s already time to start again – this time with the onions that will feed you next summer. Yes, August is the perfect time to sow hardy onion varieties from seed, and I promise it’s easier than it sounds (and more satisfying than you’d think).

🧅 Why sow in August?
Onions sown now get the benefit of warm soil to help them settle in before winter. They’ll germinate quickly and build strong roots while the days are still long. Come spring, they’ll already be established and ready to shoot up for an earlier and often bigger harvest.

🧅 Choose the right varieties
You’ll want hardier types that are bred for overwintering – we’ve put together a special offer pack with, Kosma, Musona White Italian and Senshyu Yellow Globe – or you can go for a trusted name like Ailsa Craig. Despite the name, Spring Onions are also quite happy being sown now and even into early autumn – so don’t be put off!

🧅 Three ways to sow onions from seed
There’s no one right method – it depends on your space, time, and how much faff you’re up for. Here are the three ways we do it:
1. Direct sowing into the soil
This works well if you're growing a lot of the same variety and don’t mind thinning out seedlings later.

•    Sow into well-prepared soil that’s had a good rake over – you’re aiming for a fine texture.
•    Avoid sowing into very wet ground – let it drain first.
•    Sow seeds thinly into rows 1–2cm deep, spaced 15–30cm apart.
•    As they grow, thin the seedlings gradually until you’re left with about 15cm between each plant.
•    Don’t waste the thinnings – use them like chives!

2. Seed trays and pricking out
This one’s for the perfectionists – a bit more hands-on but gives excellent results if you’re after big onions.

•    Sow thinly on damp compost, cover with 1cm compost, and wait for germination (around three weeks).
•    Once they’re at ‘crookneck’ stage (still bent over with both ends in the compost), prick them out and space them about 5cm apart in trays.
•    Grow them on until they’ve got 2–3 leaves, then transplant outdoors in October, 15cm apart.

3. Modules – the happy middle ground
This is our go-to method – it’s quick, easy, and gives a reliable crop without too much fiddle.

•    Pop 4–6 seeds into each module filled with damp compost and cover with 1cm more compost.
•    When they’re up and starting to straighten, plant out the whole clump.
•    Space clumps 20–25cm apart each way – the onions will push themselves apart as they swell.

(If you’re short on time or patience, this is the one to go for – though the individual onions won’t be quite as big as with method two.)
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🧅 What onions want

•    A sunny, open site.
•    Fertile, free-draining soil – sandy beds are ideal but not essential.
•    Good weed control – onions really don’t like competition.
•    A spacing that matches your hoe width makes weeding easier in spring.
•    A seaweed feed in early spring helps give them a post-winter boost.

For tricky soil or wetter spots, try building an onion hummock – just mix a 4cm layer of compost into the surface of the bed and heap it slightly. It improves drainage and gives them a raised, cosy spot for the winter. Avoid manure, and if your soil’s acidic, consider a little lime – onions, especially spring onions, prefer it on the alkaline side.
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🧅 A note on timing

To make it through the winter well, your onion seedlings need to be about 15cm tall by mid-October. If yours are a little behind, pop a few open-ended cloches over them to help them along without cooking them.
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🧅 A quick note on spring onions

You can sow spring onions right now too – and keep going into September and even October. Great varieties for late sowing include Eiffel, Entita, Tipika and Winter Hardy White Lisbon. Perfect for stir fries and salads well into the colder months.
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Next time, I’ll share tips on harvesting, drying, storing and cooking – including one of our favourite soups and a super easy way to roast onions. And if you're trying a new sowing method, let me know how you and your onions get on!