During August the days are still warm and fairly long but night temperatures are starting to drop, resulting in heavy dews, and towards the end of the month the first signs of autumn appear. The rainfall is variable; some years it may be very heavy but in others there will be insufficient for the plants’ requirements and you will need to water.
Strong winds can occur in August, which may cause considerable damage. Stakes, especially those supporting runner beans, should be checked to ensure that they are secure in the ground and that the plants are firmly tied into position.
Continue to deadhead and water as necessary. Cease feeding after the middle of the month. Remove untidy growths in the herbaceous border. Continue to disbud dahlias and chrysanthemums to ensure large blooms, and keep them watered.
Sever stems of carnations and pinks that were layered earlier in the year and have now developed roots. The centers of wallflower plants in the nursery beds should be pinched out when they are 10cm/4in tall.
Order spring bulbs, plant the first hyacinths and ‘Paper White’ narcissi for forcing in bowls. Plant colchicums and autumn crocuses as they become available.
Continue to take cuttings of geraniums and fuchsias. Stop young rooted cuttings to produce bushy plants. Pinch out the growing tips of coleus (solenostemon) to encourage side growths.
Keep the lights and door open, but in cold areas they should be closed at night towards the end of the month. Flowering plants should be fed weekly. Remove the bottom leaves from tomato plants; this helps the fruits to ripen and will encourage the movement of air and so reduce the possibility of disease. Keep a careful watch for mildew on cucumbers. Thin the fruit bunches of grapes, removing all small and malformed berries.
Cut back the canes of loganberries, tayberries and raspberries when they have finished fruiting. Tidy strawberry beds. Continue to harvest soft fruit. Start gathering early apples, pears and plums. Summer-prune cordons and espaliers to produce extra spurs. Complete the thinning of late apples and pears.
Check bands placed around the trees and destroy any insects found. Fruits grown against the wall should be netted to protect them from birds. Trees on dwarfing rootstocks have roots that are greatly reduced in spread and during very dry spells these should be thoroughly soaked once a week.
Failure to do this can result in the trees under stress aborting their fruit. Inspect fruit trees to ensure that they are not producing excessive wood and little fruit. This will almost certainly be due to an excess of nitrogen. Prune back hard in the winter and apply a fertiliser rich in potassium and phosphates.
Pests and diseases
Continue to spray roses against black spot and other fungal infections. Look for signs of aphids, particularly – spray with a systemic or non-systemic insecticide or horticultural soft soap. Be on the lookout for small round holes (the sign of damage by thrips), weevils chewing at the edge of leaves, and large areas of petals chewed by earwigs. Where appropriate, spray with a contact insecticide. Watch out for signs of mildew attack on marrows, peas and flowers such as Michaelmas daisies and rust on antirrhinums. Spray as necessary.
Protect dahlias and chrysanthemums against earwigs by placing an inverted flower pot filled with dried grass at the top of the stake or smear a little Vaseline around the stems to stop pests from reaching the flowers. Look out for black aphids, particularly on dahlias (spray with a systemic insecticide). Red spider mite and leaf miner are major problems on chrysanthemums (spray with a contact insecticide).
Brown rot (in which fruit first turns brown, then produces pustules) will be clearly noticeable this month. Pick affected fruit from the tree, gather any fallen fruits and destroy it all.
Keep a lookout for aphids on marginals; wash them off into the water. Never use insecticides where they might enter the water. When the day temperature is high, switch on the fountain or waterfall to oxygenate the water.
Harvesting of crops is the main activity this month. Pick runner, stringless and French beans; gather them while still young and tender, which will encourage further cropping.
Onions and shallots should be lifted as soon as the tops have dried. On warm days, allow the onions to stay outside in the sunshine; bring them inside during wet days and in the evening when they may be affected by heavy dews. Take great care not to damage the bulbs as once bruised they soon begin to decay. When the skins are fully dried, the onions should be suspended in a net from the ceiling of the garage or greenhouse.
Herbs can be gathered this month for drying. They should be hung in bunches in the greenhouse. Store the leaves in airtight containers.
Continue to remove side-shoots from tomatoes. Pinch out the tops when greenhouse plants carry six trusses and those out of doors four. Make sure that you water regularly during dry spells. Give a weekly liquid feed.
Make a final sowing of ‘All the year round’ lettuce at the beginning of the month and the cos variety ‘Winter Density’. Also sow radishes and corn salad (lamb’s lettuce), which makes a useful addition to early spring salads. Sow Japanese onions such as ‘Senshu Yellow’, which will mature a full month before spring-sown varieties, and winter white bunching onions for early spring onions. Sow spring cabbages such as ‘April’, ‘Harbinger’, ‘Spring Hero’, and ‘Wheeler’s Imperial’.