Tips for August

Flower garden

Watering container plants

Ensure containerised plants especially evergreens never go short of water during the summer while they're developing their flower buds for next spring's display. A shortage of water now can lead to a case of bud drop next year for plants, such as camellias and rhododendrons. Pots that have dried out should be submerged in water and left to soak for a few hours, ideally in a bowl, bath or water-butt. Even if it rains, pots often remain dry as they stand in the rain shadow of a house and their foliage acts as an umbrella. Keep your containerised plants healthy with our tips for effective watering.

Supporting plants

Support the stems of tall perennials and lilies with bamboo canes and watch out for lily beetles and their larvae. Pick any off and destroy them immediately.

Deadheading

Deadhead roses as the blooms fade, cutting off the flowers just above the uppermost leaf on the stem. Trim back lavender bushes after flowering to remove the old blooms and shoot tips. Take care not to cut back too heavily into any old wood. Removing faded flowers from perennials and annual plants will also ensure a continued display of blooms.

Dried flowers

Cut everlasting flowers, such as helichrysum and achillea, and grasses, such as pennisetum, when they are at their peak. Hang them upside down in a warm, airy position to dry naturally, ready for decorative arrangements.

Prune wisteria

Summer prune wisteria this month, shortening their long wispy sideshoots back to about five or six leaves from the main framework. If the plant's flowering performance was poor last spring, drench the soil with a high-potash fertiliser for an improvement.

Clematis

Clematis thrive in fertile, well-drained soil in sun or partial shade, but ensure the roots and base of plants are in the shade to keep them healthy. Blackened shoot tips may indicate clematis wilt. Cut out affected stems, but leave the main pruning until late winter and early spring. Discover the best way to train clematis. Pruning wisteria and trimming clematis are among the jobs for August

Greenhouse

Shading

Make sure your plants are well shaded on hot days to prevent scorch. The easiest way to do this is to apply netting or shade paint to the outside of the glass. Scorch is exacerbated if leaves are wet, so take care to water plants carefully.

Damping down

Damp down the greenhouse floor every morning on hot days to increase humidity. The plants will love this and it also helps to discourage red spider mite.

Tomatoes

Regularly pinch out any tomato sideshoots and tie the leading shoot to its support. Feed plants weekly with a high-potash tomato fertiliser, never letting them go short of water. Our guide to using a growing bag has more tips for growing tomatoes.

Cucumbers

Pinch out the tips of sideshoots to a couple of leaves beyond any developing fruits. Remember to pick any cucumbers regularly, as leaving old fruit on plants delays further flowering. Greenhouse jobs to do throughout August include watering and damping down

Kitchen garden

Harvesting crops

Regularly pick small and tender courgettes, carefully cutting them off at the base with a sharp knife. Wear gloves if your hands are particularly sensitive to their prickly leaves and stalks. Many other crops will also have a better flavour if harvested when still quite small.

Soft fruit

Pick the last raspberries, then prune the stems of summer varieties down to soil level. Tie in new shoots, about 10cm to 15cm (4in to 6in) apart, and remove excess ones. Prune back the main shoots and sideshoots of gooseberries to five leaves to encourage them to produce fruiting shoots for next season. Peg down strawberry runners from new plants into the soil or pots of compost to root. Shear off the foliage just above the crown of each plant and clear away any debris.

Transplant crops

Transplant young winter vegetable crops from their seed-bed when their stalks are about the thickness of a pencil.

Crops to sow

The following vegetable crops can be sown now directly outside: lettuce, Chinese cabbage, spring cabbage, endive, kohl rabi, radish, winter spinach and turnips for their green tops.

Potatoes

Hot and humid conditions can encourage a rapid spread of potato blight, so you could consider spraying the crops with a chemical fungicide to prevent an attack. Extra water given to potatoes can also boost yields.

Apples

Finish summer pruning the sideshoots on trained apple trees. Find out how to grow espalier apple trees.

Crops to sow

The following vegetable crops can be sown now directly outside: lettuce, Chinese cabbage, spring cabbage, endive, kohl rabi, radish, winter spinach and turnips for their green tops. Pruning soft fruit and harvesting are essential tasks for August

General care

Holiday watering

There are several things you can do to help prevent plants drying out. Move any baskets and containers out of full sun to a position where they are shaded at the height of the day. Stand terracotta pots on gravel trays topped up with water, so the pots can gradually absorb the reservoir of liquid. You can also install an automatic trickle watering system on an outside tap, which is controlled by a timer and will turn water on and off each day.

Take Cuttings

Continue taking summer cuttings of fuchsias, pelargoniums and tender perennials. These root quickly at this time of year, forming sturdy young plants that will successfully overwinter on a bedroom windowsill. Many houseplants, including coleus and African violets, can also be propagated from cuttings now. Take a look at our propagation section to discover which other plants can be grown from cuttings.

Trim hedges

Trim hedges, especially hedging conifers that can become tall and annoy neighbours. Be considerate, and cut their tops down to 3m (10ft) at a maximum. Our guide to pruning hedges has more useful tips.

Pests

Watch out for ants nesting in patio pots, where they can disturb root growth and reduce a plant's performance. Standing pots in a large saucer of water helps deter them from settling in. Vine weevil is a particular problem in greenhouses and patio pots. Now is a good time to treat compost with biological pest control nematodes, which search out and kill weevil larvae. They can also be applied to the soil around attacked plants.

Lawns

To achieve a fine finish, cut your lawns more than once a week. Spot treat and dig out weeds, filling holes with gritty compost, and rake a little grass seed into bare patches if necessary. In hot, dry weather, keep grass longer by setting the mower blades higher.

Weeds

Hoe weeds out of gravel paths, then carefully apply a residual path weedkiller to keep the area weed-free.

Pond care

Top up the sunken water-levels in garden ponds

Bulbs

Order spring-flowering bulbs from mail-order suppliers ready for autumn planting.

Pond care

Top up the sunken water-levels in garden ponds