Feeding plants - To keep fruiting plants (like tomatoes and aubergines) growing well and producing fruit they will need weekly feeding with a high potash tomato feed. You can make your own feed with comfrey soaked in a bucket and added to water. See recipe in shop or ask at PL Alan Smith and at HL Joe Brister.
Because they are hungry plants with a long growing season, brassicas need a different feeding regime. Top dress with a balanced fertiliser like Growmore once established. You need to maintain continuous growth or cabbages will also run to seed.
Hoeing - Weeds will be growing as well as crops and taking nutrients, your crops need so it is important to keep hoeing regularly. It is also important to get rid of the weeds before they seed, making less work for next year.
Crop protection - Make sure your brassicas are netted to protect them from cabbage white butterflies and pigeons.
Keep plot clear of old withered foliage because this attracts slugs. Slugs don't like hot dry weather, so an evening patrol is a good time to collect them. You can put down small pots of beer as traps to catch slugs and if you must use pellets please use them with great care.
Watering - Apart from targeted watering of the very water hungry plants like courgettes you only need to water in very hot weather. However, when weather is very hot and dry you will need to water onions and lettuces to reduce the risk of them running to seed. Check the soil is damp under the surface near plants and if water is needed remember that one good soak is best. The runner bean is the only plant that needs water on its leaves. When they start flowering an occasional fine spray of water will improve pollination.
More sowing - There is still time to grow salad from seed this month (lettuces take 8 weeks to mature). Sow direct or begin on windowsill. Most varieties will also work as cut and come again and there are lots of interesting salad seed mixtures on sale.
Plant your spring cabbage and broccoli seeds this month.