Is it worth sowing vegetable seeds in a drought?
Yes, it is worth sowing in a drought, as long as you choose crops that germinate fast and get past two or three true leaves quickly. After that point chard, beetroot, kale, rocket, mustards and spring onions all cope with dry spells far better than anything sown in spring.
The soil is on your side in August. It is warmer than at any point in the growing year, so seed that would sit sulking in April can be up within days. What you have to manage is moisture at the surface for the first week, and that is a technique problem rather than a weather problem.
- What to sow in August
- Salads that work in the heat
- Getting seed to germinate in dry soil
- Watering: deeply, not often
- Shade, and improvised cloches
- Why summer lettuce will not heart
- Frequently asked questions
What to sow in August
August is a second act rather than a closing chapter, and the best beds for it are the ones just cleared of peas or early potatoes.
- Radish. The sprinters, ready in three or four weeks, and they love warm soil. 'French Breakfast' is the reliable one.
- Spring onions. Hardy enough to establish now and stand through the cooler months. 'White Lisbon' is the standard for a reason.
- Chard. Fast, generous and still cropping into autumn. A brightly coloured mixture like 'Fireworks' earns its place twice over, since it looks like an ornamental.
- Beetroot. For baby beets or for the leaves. Choose a bolt-resistant variety.
- Kale and spinach. Both grow sturdily as the temperature eases off.
- Dwarf French beans. Bush varieties only, not climbing, sown early in the month for a late flush of pods before the first frost.
Shortening days work in your favour with leafy crops. They grow tender and well-flavoured instead of bolting, which is the opposite of what happens to the same seed sown in June.
Salads that work in the heat
Cut-and-come-again is the right model for an August sowing. You are after leaves you can pick repeatedly, not a crop that has to reach maturity before the weather turns.
- Loose-leaf lettuces such as 'Lollo Rosso', 'Salad Bowl' and 'Oakleaf', which cope with warmth and can be cut again and again
- Rocket, which behaves far better sown in August than in midsummer, and suffers less flea beetle damage as the season cools
- Oriental greens such as mizuna, mibuna and tatsoi, which are very fast indeed
- Mustards such as 'Red Giant' and 'Green Frills', which actually enjoy the lingering heat
- Corn salad, sown towards the end of the month for picking through autumn and into early winter
Our own seed range is small and chosen rather than comprehensive, so you will find the chard, radish and spring onion above in it but not the full salad list.
Getting seed to germinate in dry soil
This is the part that decides whether an August sowing works, and there is one technique worth more than all the rest.
Cover the seed row with a plank or a piece of cardboard for three to five days. It traps moisture, shades the soil and holds a cool, still, damp microclimate exactly where the seed is. Lift the cover the moment the first seedlings show, and water gently from then on. Leave it on a day too long and you get pale, drawn seedlings.
Around that:
- Water the drill thoroughly before you sow, not after. Watering a dry surface afterwards runs off or crusts.
- Sow slightly deeper than usual, while staying within the depth on the packet, to keep the seed away from the hottest surface layer.
- Mulch lightly around young plants once they are up, with compost or fine leaf mould, to slow evaporation.
Watering: deeply, not often
The aim before germination is different from the aim after it. Until the seed is up you are keeping the top centimetre damp. Once it is up you are training roots downwards, and light daily sprinkles do the opposite by keeping every root near the surface.
- First three to five days: water each evening
- After emergence: every two or three days, a proper soak each time
- At two true leaves: often down to twice a week, depending on rain and soil
Sandy soil needs it more often, clay holds on longer. And do it in the evening. The soil is cooling, evaporation drops away, and the seed gets a full night in moist ground rather than a few hours before the next day's heat. In a hot spell, sowing after six o'clock becomes the ritual.
Shade, and improvised cloches
A few days of shade through the hottest part of an August afternoon makes a disproportionate difference to a new sowing.
A propped board or an old sheet will do. If you want something more permanent, bend lengths of chicken wire into a V or tent shape over the row and drape horticultural fleece across it, held on with clothes pegs. It shades, it holds a little humidity, and it keeps the pigeons off. We do not stock fleece, so that is a garden centre errand rather than a plug.
Containers are easier still: move them somewhere sheltered and shaded until the seedlings are established, then bring them back out.
Why summer lettuce will not heart
Hearting lettuces are cool-weather plants. In August heat they grow loosely rather than forming a tight centre, and they bolt more readily, which is why a summer sowing so often ends in a bitter, leggy plant.
That is not a failure of technique. Light shade and steady moisture will reduce the stress, but they will not produce a heart in the middle of a hot month. Sow loose-leaf types now and keep the hearting varieties for early spring or early autumn, when they will do what you want without a fight.
The rest of the growing kit sits in Gardening & Growing, and there is more on compost and seed-sowing mixes in our guide to coir compost.
Frequently asked questions
Is it too late to sow vegetables in August?
No, and in some ways August is easier than spring. The soil is warmer than at any other point in the year, so seed germinates quickly, often within days, and shortening days encourage leafy crops to grow tender rather than run to seed. Radish, spring onions, chard, beetroot, kale, spinach and dwarf French beans all suit an August sowing. A bed just cleared of peas or early potatoes is the obvious place to put them, and you get a crop from ground that would otherwise sit empty.
How do you keep seeds moist enough to germinate in dry soil?
Water the drill thoroughly before sowing rather than after, sow slightly deeper than usual while staying within the depth on the packet, and then cover the row with a plank or a piece of cardboard for three to five days. The cover traps moisture and shades the soil, creating a cool, damp pocket exactly where the seed is. Lift it as soon as the first seedlings appear, or they will be drawn and pale, and water gently from that point on.
How often should you water newly sown seeds in a drought?
Every evening for the first three to five days, to keep the surface damp until the seed germinates. After emergence, switch to a deep soak every two or three days rather than a daily sprinkle, which trains roots downwards instead of keeping them at the surface. By the time plants have two true leaves you can often drop to twice a week. Sandy soils need watering more often than clay, and a light mulch around young plants cuts evaporation considerably.
Is it better to sow in the morning or the evening in hot weather?
The evening. The soil is cooling, evaporation slows right down, and the seed gets a full night in moist ground before it has to face any heat. Morning sowing is fine on a mild day, but in a hot spell the surface dries out within hours and you lose the moisture you have just added. Evening watering also lets seedlings take up water and root a little before the next day's sun. Salads and spinach benefit most, though chard and beetroot notice it too.
Why do my summer-sown lettuces not form hearts?
Because hearting lettuces are cool-weather crops and August is too warm for them. In heat they grow loosely rather than forming a tight centre, and they are far more likely to bolt and turn bitter. Light shade and consistent moisture reduce the stress but will not produce a heart in the middle of a hot month. Sow loose-leaf types such as 'Salad Bowl' or 'Oakleaf' for a summer crop, and keep hearting varieties for early spring or early autumn sowings.
Written by David Hurrion
David Hurrion is a trained horticulturist, teacher and journalist who has worked on nurseries, taught at colleges, and edited some of the nation's leading gardening magazines. He chooses everything Norman & Vera stocks, and makes practical gardening videos for BBC Gardeners' World Magazine.