August might feel like the tail-end of summer, but there’s still plenty to be getting on with in the garden. While the days are long and warm, it’s the perfect time to stay ahead of late-season growth, keep your beds and borders blooming, and give your veg patch the attention it deserves. August is a month of maintenance and momentum, keeping things ticking over, you’ll thank yourself come autumn!
This is the time to feed generously and make the most of what’s already thriving. Whether you’re topping up your compost heap, pruning spent shrubs, or giving your kitchen garden a mid-season boost, it’s all about keeping the garden happy and productive. There’s still colour to enjoy, crops to pick, and the promise of more to come.
So grab your trug and let’s dig into the key jobs that’ll help your garden stay healthy, tidy, and full of life right through to the first frosts. From borders to beans and compost bins to clematis, August is far from sleepy… It’s your garden’s second wind.
Start with Glorious Beds and Borders
Give your border plants a helping hand through prolonged periods of dry weather by covering bare areas of soil with a thick layer of mulch. A 10cm thick carpet of garden compost, leaf mould or well-rotted manure will lock in moisture for longer. Water the soil first or apply once it has rained.
Control leaf disfiguring powdery mildew on Michaelmas daisies by spraying with a copper-based fungicide. Repeat the treatment every two weeks.
Rejuvenate large clumps of iris. After a few years, the centre of clumps can die off and plants will be reluctant to flower. To restore vigour, prise from the ground with a fork and divide up the outer sections of the plant with a knife. Cut straight across the leaves, 15cm from the roots, and replant 15cm apart.
If you are growing any top-heavy perennials that flower late in the season, give them support to prevent them from toppling over in a sudden downpour or gust of wind. Place four stout canes around dahlias, asters, and helianthus, then tie a length of twine to a cane and enclose all the stems by wrapping it around the rest of the canes. To ensure plants don’t flop, keep the twine tight.
Enjoy delicate splashes of colour in September and October by planting colchicums in borders now. These sophisticated bulbs, also known as autumn crocus, have funnel-shaped flowers in white and many shades of pink. Plant 10cm deep, in a sunny spot.
Sweet and Delicious Fruit!
It is super easy to make more strawberries by potting uprooted baby plants, also known as runners. Severe the stem between the runner and mother plant, then prise it carefully from the soil with a hand fork. Remove any dead leaves and pot into a small container filled with compost.
Grab your secateurs and give cordon, espalier and fan trained apple and pear trees a summer prune. Start by looking for this season shoots and cut any that are 20cm long and growing from a side branch, back to one leaf. Any new shoots growing from the main branch should be reduced to three leaves.
Order new trees, bushes, and cane fruit for planting in autumn.
Reduce the risk of brown rot fungal disease spreading to healthy apples and plums on the trees by removing any fruit that has rings of white spores or soft brown patches on the outer skin. Put in the wheelie bin, not on the compost heap.
Kitchen Garden Treats!
For the best greenhouse cucumbers, pinch out the leader, or uppermost shoot, when it reaches the top of the structure and shorten side shoots, leaving two leaves beyond each developing fruit.
Speed up the ripening of squash plants by removing any large leaves that shade the developing crop from the sun.
Lift onions from the soil when leaves have withered and turned a straw-brown colour. If the weather is good leave them on the soil for a couple of weeks to dry or bring them indoors if raining. Store in wooden fruit boxes.
If you find a black, flat hard patch on the bottom of tomatoes, this is a sign of blossom end rot. A common problem caused by a lack of calcium, which is found in water. Avoid damage to your fruit by watering daily, or even twice a day during hot weather.
Sow overwintering salad onions, Japanese onions, spring cabbage, turnips, and carrots in vegetable gardens.
Ensure courgettes remain productive by picking young fruit regularly. Harvest when they are about 10cm long to encourage more to grow and to prevent them from turning tough and woody.
Pay Trees and Shrubs Some Attention
Trim evergreen hedges so they look good across winter. During summer, box, privet, laurel, and other hedging plants will have put on lots of growth, turning a crisp outline into a shaggy eyesore. Use a pair of hand shears or a powered hedge trimmer, start by cutting the top of the hedge flat and then trim the sides, ensuring the top is narrower than the base.
Trim lavenders lightly when blooms start to fade, aiming to remove the spent flower heads. Prune harder in early spring, aiming to remove about 5cm of growth.
Large-flowered clematis will now be in full flight, but are particularly prone to clematis wilt disease. Avoid problems by planting new clematis deeply – 10cm below the level it was in its pot is ideal.
If left to its own device’s wisteria will outgrow its allotted space and flower poorly. First, tie in any stems to fill any gaps on walls or trellis, then ensure a great floral display next year by cutting back all the whippy shoots produced during the current season to five to six leaves – this will encourage buds to form.
And Finally…
Compost heaps can stop working in hot, dry weather, so ensure all your spent garden waste continues to rot by occasional watering heaps and turning with a fork. If it does not have a lid, place a sheet of cardboard or a piece of old carpet on top to retain moisture and heat.
A spell of hot weather can dry up birdbaths, so top them up regularly to ensure there is always a fresh supply of water.
As the evenings start to get cooler, close greenhouse vents, doors, and windows at night to lock in warmth. Remember to open again in the morning to avoid the build-up of excessive temperatures during the day.
