Lawn growth slows down in late summer – raise the cutting height of your mower slightly to help the grass resist the wear it suffers at this time of year.
As weeds are growing prolifically at this time of year, make sure you keep them under control. Many safe weed-killers are available for use on patios, driveways, borders and lawns – if you’re unsure, you can get advice from your local garden centre.
Weeds in lawns such as dandelions, daisies, lesser trefoil etc can now be treated with Weedol lawn weed-killer. For best results, don’t mow the lawn for three days before treatment.
Give hedges a final trim over now, as they will only grow a little more before the cold weather stops growth. Hedges trimmed now will grow enough to hide any pruning wounds before the winter.
Rhododendrons and camellias can suffer from bud drop before flowering in the spring. The most common cause of this is lack of water now, when buds are beginning to form. Keep plants well-watered and apply a mulch of composted bark around the base of the plants to help retain moisture.
Give your lavenders a light trim after flowering, but be careful not to prune too and cut into older, leafless growth. Old wood won’t reshoot, and the plant may die as a result.
Wisterias can now be given their summer pruning. All young, whippy side shoots produced this year should be shortened to within five or six buds of the main stem.
Regularly deadhead summer bedding plants and feed them with a high potash fertilizer to encourage more flowers.
Continue to deadhead roses, dahlias, penstemons and fuchsias to prolong the display of colour well into the autumn.
Take cuttings of tender plants like geraniums, fuchsias and osteospermums, and keep them in a light but shaded position until they’ve rooted.
Autumn and spring-flowering bulbs can now be planted into beds, borders, patio pots and window boxes.
Water and feed all plants growing in patio pots and containers – even after a heavy rain, these plants will still require watering.
Fruit & vegetables
Summer-prune espalier, fan-trained, cordon and step-over fruit trees. Check for any signs of aphids or caterpillars, and spray if required.
Onions and shallots should soon be ready to harvest. When the leaves turn yellow and the tops bend over, carefully lift the crop, shake off the soil and leave then out in the sun to dry fully before storing.
Tomatoes growing outside can have their tops pinched out when three or four flower trusses of fruit have formed – this will encourage the fruits to develop and fully ripen before the end of the season.
Harvest early-cropping apples, ensuring the fruit really is ready for picking by gently cupping a fruit in your hand and giving it a subtle twist. If the fruit is ripe it will easily come away from the tree.
Marrows, pumpkins and squashes can be rested on pieces of wood or polystyrene while they ripen. Fruits sitting on the ground can rot or suffer slug attack, especially during wet weather.
Bush cherries and plums should be pruned after they have fruited. Take out any dead, damaged, rubbing or crossing branches, then thin out to let the light and air into the tree.
Support any heavily laden branches of plums, apples and pears to prevent long term damage to the tree.
Regularly harvest fast-maturing vegetables like French and runner beans, courgettes, cucumbers and tomatoes to prevent stringy or tough vegetables, and encourage further cropping.
Cut out fruited canes of summer raspberries, and tie in new non-fruited canes to fruit next year. Select only the strong healthy canes, removing all weak canes completely.
Carrots benefit from protection against the second generation of carrot flies that will appear this month. The most effective control is to cover the entire crop with horticultural fleece.
Check any houseplants which you’ve placed outside during the summer. Be particularly watchful for pests such as aphids, mealybug, red spider mite and vine weevils, and spray with a systemic insecticide such as Bug Clear Ultra.
Now is a good time to apply biological controls for wine weevil. The grubs will be starting to hatch, and soil temperatures are good, so take this opportunity to treat vulnerable plants (both in the ground and in pots) like rhododendrons, camellias, heucheras, cyclamen, fuchsias and primulas.