August

Still plenty of time to sow:

Lettuce, short carrots, radish, spinach, spring onions, chard, courgettes, runner beans, rocket, pak choi.

Other jobs:

Tomatoes – take side shoots off tomatoes and remove yellow leaves. Pinch tops out when they reach the top of greenhouse.
Onions – ripen by bending leaves just above neck of each plant.
Leeks – blanch by earthing up around stems, be aware that early maturing leeks may not last over winter.
Broad beans – If you cut them to 3 shoots they will grow again and you will have a few extra beans.
Runner beans – pinch out tops when they reach the top of the cane.
Cabbages – feed winter cabbages with a nitrogen feed.
Cauliflowers – harvest and wrap in cling film, they will last longer in fridge.
Courgettes – pick by twisting them off. Make sure you pick them regularly or they will stop fruiting.
Potatoes – If you want to store for a bit longer, cut the tops off and leave in ground for 10 days, then lift.
Pick – cucumbers by cutting with a sharp knife, pick runner beans young, they taste better and are less stringy, pick French beans when they snap easily.
Weed around plants.
If you have any empty ground try sowing some green manure, it will improve the fertility of your soil.
Stake brussel sprouts and purple sprouting.

Fruit:

Prune simmer fruiting
Prune stone fruits such as plums, peaches, etc. If you prune these in winter they will get silver leaf which can kill the tree.
Summer prune apples and pears.
Pot on strawberry

Pests and diseases:

Damp down greenhouse to avoid red spider mite.
Check brassicas regularly for any signs of cabbage white butterfly caterpillars, or whitefly.
Check for maggots in plum and apple trees, if you have them next year put up pheromone traps.
Look out for blight on potatoes.

Sources: