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August: Sowing, Planting & Care in the Plot

Runner bean flowers and pods

August with a little luck brings us the best of the summer weather. But being the traditional holiday month, it can be hard to keep on top of the vegetable plot with a fortnight away even if a neighbour can be persuaded to water as required, and with Coronavirus restrictions still in evidence. 

Direct Sowing in August

There are still quite a few things you should be sowing in August. Spring and Chinese cabbages, which are a late crop, as well as hardy lettuce. Although we think of lettuce as a summer crop, it is a surprisingly hardy plant. Protected under a cloche or in the greenhouse, it can easily be available for a Boxing day salad. It’ll be nicer than some tasteless import from sunnier climates.

Sow spring onions like “White Lisbon Winter Hardy”. It will grow, albeit slowly, and add zing to that salad along with some fast-growing radishes.

Late spinach can be sown in August with a last sowing of kohlrabi and turnips.

Planting Out in August

Plant out savoy cabbages and cauliflowers to grow on for the earliest crop of the year as well as hardy kales.

Cultivation, Pests & Problems

Your runner beans will be at the top of the canes now. So, pinch out their growing tip to encourage bushier growth below. Pick all runner, climbing and dwarf beans regularly except for the haricot varieties such as Borlotti where we want the bean rather than pod for table.

Stop tomato plants now to encourage fruit to swell and ripen. Stopping is the process of cutting off the growing tip so the plant’s energy is not diverted from fruit into foliage . Keep your tomato side shoots in check. You want tomatoes not masses of foliage. Ensure they are watered regularly, as drying out prevents the plant from taking up sufficient calcium. Its deficit causes blossom end rot.

Keep on top of pests. Aphids and Blackfly are a particular problem in the greenhouse although they are certainly about in the open plot as well. You can control them with pesticides or just wash them off many plants with a strong jet of water.

A squirt with a soft soap solution will do no harm to the plants and will reduce the numbers by stopping the pests breathing. In the greenhouse, biological controls are most effective and don’t forget the traditional sticky yellow cards which attract the whitefly.


If we do get a prolonged dry spell, fruit bushes and trees will require watering. Swelling apples and currants need water as much as leafy vegetables. Give a good soaking rather than little sprinkles that encourage surface rooting.

It’s the last chance for summer pruning. Watch out for overladen plums and damsons. If needed, you can support  branches by inserting a length of 2×1 notched at the top (like an old fashioned line prop) to support the branch or tie to the stem with robust twine.

Keep the base of trees weed and grass free, mulch to keep in moisture and add fertility with garden compost.

Protect autumn raspberries from birds with netting before the fruits arrive and they eat them.

In the Greenhouse / Polytunnel

Ensure good ventilation. It can get incredibly hot in a greenhouse with strong sun and scorch your plants. You should also consider shading the house with blinds, films or a shading wash

Keep pinching off tomato plants side shoots and stop them a few leaves afbove a truss by pinching out the growing stem. Keep an eye out for pests such as aphids, whitefly and red spider mite. If you are subject to attack by these pests, it is worth checking out biological controls as they are perfectly safe to use. Used correctly, they are also more effective than traditional chemical controls.

Harvest Regularly to keep plants productive