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What to Do in the Vegetable Garden This August

Published on August 8th 2020
A pile of orange tomatoes
Happy National Allotments week! This year's theme highlights the importance of growing your own for a sustainable future. You can get involved and grow your own just about anywhere, whether in our gardens, on our balconies or even inside our homes. Join us in celebrating growing your own this week with a well-earned harvest of tasty produce from your own outside space!
Get growing with the fruit and veg collection:

Fruit and Veg

Old Hogden
Chantenay carrot seed. Royal. Open pollinated
Free delivery
Old Hogden
Carrot seed - Purple Sun F1
Free delivery
Old Hogden
Carrot seed - Atillo F1
Free delivery
Old Hogden
Chantenay carrot seed. Red cored. Open pollinated
Free delivery
Pennard Plants
Fruit Bush - Citrus, Lemon
Free delivery
Pennard Plants
Fruit Bush - Citrus, Lime
Free delivery

August is a glorious month to be out in the garden, especially if you grow your own food. Abundance is all around, and it's time to make the most of it!


  • Cabbage, Cauliflower, Sprouts and other Brassica plants get a multitude of pests at this time of year. Use fine mesh to protect vegetable crops against flying pests. It is particularly effective against Carrot and Cabbage Root Fly and caterpillars.
Insect proof net over cabbages in a garden
  • If you would rather not cover your vegetables with netting to keep pests off, try regular sprays of diluted garlic spray.
how to make organic pesticide

Make organic pesticide

Are you tired of those nasty aphids munching on your babies? Try this quick and easy organic pesticide to help clear the problem.

  • Fill spaces in the veg patch by sowing quick maturing items such as turnips or, better still, varieties that will provide tasty winter salads like , Corn Salad (lamb’s lettuce), Rocket, and Radicchio. These are not hard to grow and will provide tasty, nutritious homegrown salads in the middle of winter!
  • Trees that produce fruit with stones, rather than pips, should be trimmed now. Plums, Cherries, Apricots, Peaches and Nectarines are best pruned during the summer when they are less likely to get infected with the incurable Silver Leaf Disease. Immediately paint any significant cuts (over 1” diam.) with Seal & Heal wound healing paint.
  • Sow seeds of autumn onion [sometimes called Japanese onion] this month for the earliest crop of next year. You’ll be able to buy onion sets next month, but seeds are cheaper!
onion plants
  • Keep picking Runner Beans and Courgettes regularly. If you don’t, they will stop producing more. Both can be used to make excellent chutney or can be given to neighbours and friends.
  • Dig up your Potatoes. Dry and store undamaged tubers in a dark, frost-free place for winter. Late main-crop and winter salad Potatoes will need a little longer in the ground and may put on a lot of tuber growth in the next few weeks. First early, and most second early, varieties will be ready to lift now.
  • Harvest all Marrows and Cucumbers regularly. If you don’t, they will stop producing. Give excess produce away or conserve them. Even throwing them on the compost is better than leaving them on the plants.
A person holding cucumbers
  • Watch out for early blight on Potatoes. Only a few sprays are effective, so it might be best to cut the tops off if your crop is infected. If you don’t, the spores can be washed from the leaves and infect the tubers underground.
  • Plant more winter vegetables. As it’s late in the year for most, try to buy plug plants or baby plants. This is especially true for Leeks, Purple Sprouting, Beetroot and Kale.


  • Prune out summer fruiting Raspberry canes that have finished cropping.
  • Order fruit trees and bushes for autumn and winter planting.
  • Order Strawberry runners for late summer and autumn planting. Don’t forget to order some for planting into grow-bags - or other containers - to force under protection for the very earliest berries.
Strawberry plants and a grow bag
  • Summer prune intensively trained fruit trees. So that's plants which are espalier, cordon, fan and step-over trained.


  • Turn your compost heap over and water it thoroughly if it appears dry.
  • You can accelerate the decomposition process by mixing in some compost activator. Cover the top with an old carpet to keep in the heat generated by all the useful micro-organisms that will be breaking your garden pruning down to form good garden compost to dig in the borders in autumn.
Get some more compost tips here:
  • Compost heaps can get too dry, so check and soak them if necessary. If they are too dry, the decomposition slows down.
Composting bins in a garden

Soils, mulching and weed control

  • Creeping Thistles, Nettles and Brambles can be controlled with SBK Brushwood Killer now.
  • It’s not too late to mulch your beds and borders to control weeds. Use chipped bark, composted green waste, mushroom compost or decorative gravel.

Greenhouse and protected crops

  • Remove the leading shoot when your greenhouse Tomatoes have set five trusses of fruit. This will encourage all the fruit to ripen before late autumn.
  • Regular feeding with a Tomato feed will help this and also makes the fruit tastier!
tomatoes on the vine
  • Check greenhouses for Whitefly. They are a little bigger than midges and will fly up in clouds if you disturb them. Yellow sticky pads will trap lots of them, but don’t use them if you have introduced or encouraged natural predators into your greenhouse. S B Invigorator sprays have a physical (not chemical) mode of action, but you will need to spray very thoroughly. If you have to use chemicals, Provado Ultimate Bug Killer is currently the best available.
Find eco-friendly ways to treat pests here:
  • Powdery mildew can be a problem on some Cucumbers so remove leaves as soon as you see the typical white powdery coating. Ensure that the roots are kept moist and try controlling with a solution of 50:50 milk and water.
  • Watch out for Red Spider Mites on greenhouse plants. Symptoms include pale speckles appearing on the shoot tips, webbing of the same areas and tiny insects just visible to the naked eye. Introduce predatory mites as soon as you see this troublesome pest.
Red Spider Mite on cucumber leaf
  • Pot up a few roots of garden Mint. Kept inside you will get fresh mint well into winter.
  • This is a good time to control Vine Weevil using a nematode biological predator. It’s simple to water onto pots and borders but make certain that they are wet first and agitate the solution as you apply it.

Once you have tended to your fruit and veg, show your beds and borders some love! Find everything you need for gardening in August in the hand-curated collection:

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