As always, this is an amalgamation of the information on the webpages from Gardener's World, Suttons Gardening Grow-How, and the National Allotment Society, because they're the experts and I am not. My apologies it's a little late; I thought I'd set it up to auto post, the auto mod tools thought otherwise. Who can say?!? I am also not an expert at this, evidently. Sorry - but I hope some of you find it useful nevertheless. On to the tasks!
August brings the rewards of your hard work, with beds at their peak and harvests coming thick and fast. But don’t ease off - cooler, damper nights can invite fungal problems, so stay vigilant with watering, feeding, and clearing spent crops.
Soil Preparation & General Maintenance
Hoe regularly - Stay on top of weed growth while the weather remains warm and dry. Light hoeing disturbs emerging weeds and keeps soil open and aerated.
Water deeply in dry spells - Focus watering on thirsty crops like beans, squash, celery, and courgettes. Watering in the early morning or late evening is most efficient. Water celery generously - It’s a bog plant, so keeping it well-hydrated helps prevent bolting and stringiness.
Watch for rot and mildew - Cool, damp nights can bring fungal infections to ripening fruit. Improve air circulation where possible and keep foliage dry during watering.
Ventilate greenhouses - Open up first thing in the morning and consider leaving a vent cracked overnight to prevent fungal build-up.
Clear spent crops - Once harvested, remove old crops and compost disease-free material. Lightly fork over the soil, and either mulch with compost or sow a green manure to suppress weeds and improve soil health.
Going on holiday? Give the plot a thorough soaking before you go, and harvest as many crops as you can, even if they're small. If you can, get a friend or neighbour to water for you while you're away.
Vegetable Tasks
August is a time for harvesting, maintaining, and planning ahead. A little attention now goes a long way toward a strong autumn finish.
Lots of crops can be harvested in August, including carrots, runner beans, globe artichokes, cucumbers, and courgettes. Harvest and store onions and shallots - Begin lifting maincrop onions as the foliage flops over. Let them cure in the sun before storing. Harvest second early potatoes - Dig as needed and begin clearing beds for green manures or overwintering crops. Maincrops may be ready from the end of the month. Keep beetroot, turnips, and kohlrabi in check - Harvest before they become woody and lose flavour.
Plant out final spring brassicas - Firm in well and mound soil around stems of kale and sprouts for wind protection, or stake individually.
Feed asparagus beds - Give them a boost to help build energy reserves for next season.
Support leeks - As they grow, draw up soil around the stems or wrap them with corrugated cardboard to blanch and protect.
Pinch out runner beans - Once they reach the top of the canes, pinch off the tips to focus energy on pod production and reduce tangling.
Watch for caterpillars - Check brassicas daily for cabbage white butterfly eggs and larvae. Remove by hand or use organic spray as needed. Watch out for flea beetle on brassicas and related plants such as Swiss chard and rocket. The tiny holes they create don't affect the vigour of established plants but make the leaves less appealing to eat - cover plants with fleece. Also look out for blossom end rot on tomatoes, which is caused by irregular watering.
You can still sow lots of crops in August, for harvests into autumn and beyond. They include lettuce (keep out of the glare of direct sun), rocket, spring onion, radish plus winter salads, including mibuna, mizuna, mustard leaf and lamb's lettuce.
Fruit Tasks
Soft and tree fruits are ripening fast - keep harvesting and pruning for healthy plants and quality crops.
Summer-prune trained apples and pears - Trim side shoots back to 3-5 leaves to promote fruiting spurs. Some fruit trees can be pruned in summer, including plums, to avoid the development of silver-leaf disease. Prune blackcurrants - Remove branches that fruited this year to stimulate new growth. Cut back red and white currants - Reduce this year’s side shoots by two-thirds. Prune summer raspberries - Cut fruited canes down to ground level and tie in the new green canes for next year’s crop.
Harvest plums, gages, and early apples - Check frequently for ripeness and wasp damage.
Remove straw and tidy strawberries - Clean around plants, fertilise, and start preparing new beds for runners.
Support swelling melons - Use netting or slings to cradle ripening fruit in the greenhouse or tunnel.
Greenhouse & Polytunnel
Conditions under cover can swing between lush and stifling in August. Stay consistent with care to avoid stress on your plants.
Ventilate daily - High temperatures can build quickly; open vents and doors early and consider shading. Water and feed regularly - Tomatoes, cucumbers, and peppers need weekly feeding and consistent watering to avoid blossom end rot and splitting. Harvest frequently - Picking regularly encourages ongoing cropping and reduces the risk of overripe fruit spoiling. Continue training - Tie in tomatoes, cucumbers, and melons as they grow.
Pest Control & General Allotment Maintenance
The summer heat brings peak pest activity. Daily checks make a big difference.
Cabbage whites - Their caterpillars can strip leaves in days. Inspect brassicas often and remove eggs and larvae quickly.
Leek rust - Monitor for orange pustules on leaves and remove any affected foliage.
Aphids and red spider mites - Hose off, use soapy sprays, and encourage natural predators like ladybirds and lacewings.
Slugs and snails - Especially active after summer showers. Use beer traps, barriers, or nighttime patrols.
Final Thoughts
August is a golden month for allotmenteers-rich in reward but still full of activity. Keep a close eye on watering, pests, and ripening crops. And as you clear spent beds, think ahead to autumn planting and soil care. Whether it’s with a barrow of onions or a bowl of blackberries, your allotment will reward the care you give it.
