What to sow in August

August might feel like the tail end of summer and can be quite frenetic with all that harvesting, but don’t miss this opportunity to get some seeds sown for a productive autumn (Fall) and winter veg garden.

I’m in the UK zone 9a which equates roughly to USDA zones 8b – 9b or RHS H4 (Royal Horticultural society https://www.rhs.org.uk/advice/rhs-hardiness-rating) so much of the information below is tailored to zones that have a winter temps no greater than -5 to -10 C (14 to 23 F).

So whether you have land, an allotment a balcony, a greenhouse, a polytunnel, or even just a few pots, there are plenty of vegetables you can start from seed this month. The key is to match each crop to the right conditions, so consider light, moisture, and temperature when sowing to ensure successful germination and growth.

Leafy Greens and Brassicas:

Many cool-season crops germinate best in slightly cooler temperatures (15–22°C / 59–72°F) and benefit from being started in modules (seed trays or small pots) before transplanting to their final position. Sowing into modules will also help protect young seedlings from slugs and heat stress. However, you will still need to be vigilant as flea beetles and aphids are rather partial to a tender young cabbage leaf.

• Cabbage, Calabrese (broccoli), and Cauliflower – Start in modules in a partially shaded area; transplant to a sunny spot with firm, fertile soil.
  • Try ‘Red Drumhead’ cabbage ‘winterjewel’ F1 Cabbage, ‘All the year round’ cauliflower, ‘Gypsy’ cauliflower, and Chinese cabbage
• Kale and Chard – Sow in modules or direct if soil is moist and weed-free; they prefer full sun but will tolerate partial shade.
  • Try ‘Nero Di Toscana’ Kale, ‘Red Ruble’ Kale, ‘Bright lights’ chard, ‘Rainbow’ chard
• Spring Greens – Excellent for winter harvest; sow in modules for better control over spacing and pests. Spring greens are a cultivar of ‘Brassica oleracea’ they don’t form a head but are use for their leaves.
  • Try Cabbage ‘Verve’ F1 (Spring Greens), Cabbage (collard) F1 ‘Sweetie’

Keep the compost consistently moist but not soggy, and ensure good airflow to reduce fungal issues. Brassicas benefit from netting against cabbage white butterflies. When transplanting from the module tray into their final position make sure you firm them in well. Brassicas like really firm soil around their roots as it gives them stability.

For netting I would suggest getting some ‘Enviromesh’ – it’s a wee bit expensive, but it won’t rip and lasts for years (i’ve had one piece for at least 4 years).

Quick-Growing Roots and Salads:

Direct Sow Outdoors

Some root crops and salad vegetables thrive when direct sown into warm, moist soil. They germinate quickly and don’t respond well to transplanting. Having said that I do know folk who plant carrots in module trays and have a fine crop. I’ve never had much success with that and find it better to direct sow – but each to their own.

• Carrots – Choose fast-maturing varieties; sow directly into loose, stone-free soil in a sunny spot. Germinate best at 18–22°C (64–72°F).
  • Try ‘Autumn King’ or ‘Nantes 5’ (although some seed packets may stop in July a sowing in early August is always worth a try)
• Radishes – Sow little and often for a continuous supply; they mature in as little as 4 weeks. Try a small sowing every couple of weeks.
  • Try ‘Diana’ (small round radish) or ‘French Breakfast 3’ (a longer radish)
• Turnips – Best sown directly; grow quickly and do well in sun or partial shade.
  • Try ‘Snowball’ or ‘Sweetbell’ F1
• Lettuce, Rocket (arugula) Direct sow into moist soil or containers in partial shade to prevent bolting.
  • Try Rossa Di Trento’ or ‘Lollo Bionda’
• Beetroot – is always worth a try in early August – in seed trays or direct in warm moist soil. A polytunnel or greenhouse would be preferable for the extra warmth and protection.
  • Try ‘Choigga’ or ‘Boltardy’

Water gently and frequently until germination. A light covering of fleece or mesh can help keep moisture and deter pests particular when seeds are germinating or very young. Many people recommend covering carrot seeds with a plank of wood until they have germinated. I use a piece of thick green netting doubled over which seems to do the job.

Warm-Weather Crops: Use a Polytunnel or Greenhouse

Although August weather may start cooling down a bit, there’s still time to sow some warm-weather vegetables under cover, especially if you use a polytunnel, greenhouse, or cold frame.

• Courgettes (zucchini) – Still viable if started early in August under cover; they need warmth (above 18°C / 64°F) to germinate. Grow in rich, well-drained soil with full sun.
  • Try ‘Black Forest’ F1 or ‘Defender’ F1 ) again the seed packet may tell you that end of June is your last sowing, but they are always worth a go if you have the right conditions)
• French Beans (bush or dwarf varieties) – Can be direct sown in a greenhouse border or in large containers.
  • Try ‘Faraday’ or ‘Purple TeePee’
• Spring Onions – Start under glass or outdoors in a sunny position. Keep soil moist for even germination.
  • Try ‘White Lisbon’ (Winter Hardy) or ‘Ramrod’ (salad bunching)

These crops need warm, sheltered environments and consistent moisture. Mulching  can help retain soil temperature and reduce evaporation. Make sure you water regularly.

Under Cover:

If you have a cold frame, cloche, or even a greenhouse or polytunnel, now is a great time to make use of it. These protect seedlings from harsh winds, pests, and temperature fluctuations—especially helpful for late sowings.

Ideal crops to sow or harden off under cover include:

• Pak Choi – Prefers moist, fertile soil and partial shade; great under glass.
  • Try ‘Hanakan’ F1 or ‘Rubi’ F1
• Spinach – Sow into pots or borders under a cold frame for autumn harvests.
  • Try  ‘Rubino’ F1 spinach or ‘Comred’ F1
• Herbs like coriander, parsley, and chervil – Prefer cooler temperatures and partial shade.

Ventilate cold frames during the day to prevent overheating, and water in the early morning to avoid fungal problems overnight. Keep green house or poly tunnel doors open for good airflow and pollinators.

In Summery

With a little planning and the right sowing methods, your garden can keep producing long after summer ends. Sow leafy greens in modules for transplanting, direct sow quick roots and salads outdoors, and take advantage of polytunnels and frames for warm-loving or late crops. Keep soil moist, provide some shade for tender seedlings during heatwaves, and ensure plenty of airflow for healthy growth.

As with all gardening there are tried and tested methods – but equally if you have the time and the space you have nothing to lose from a little experimenting. If it grows, brilliant – if it doesn’t then you will have learned something about your growing season. Both are equally valuable lessons.

Let me know in the comments what you are planning to sow this Autumn (Fall) and what zone you are gardening in. It’s fascinating to hear about the variety of vegetables that can be sown around the globe.

Thanks for reading – solitaire gardener