August is the last official month of summer, so it’s the perfect time to enjoy your garden while it’s still at its best. Children are on school holiday, lawns are in full use, and there’s plenty of delicious fruit and veg to fill your dinner plate.

If you’re planning a holiday in August, remember to get a friend or family member to water your lawn whilst away.


Timely Tips

August isn't the time to take your eye off the ball in the garden. Here are some of the main jobs:

  1. Top up ponds and bird baths regularly.
  2. Water fruit and veg plants daily.
  3. Prune all summer flowering shrubs, such as climbing hydrangeas, once the blooms are finished.
  4. Keep on top of weeds as they compete with your crops for nutrients and water.


In The Flower Garden

  • Water evergreen shrubs like camellias and rhododendrons thoroughly this month to make sure that next year's buds develop well.
  • Keep patio container plants well-watered and feed with a liquid fertiliser every fortnight.
  • Stake tall or top-heavy dahlias and lilies to prevent wind and rain damage. Dead-head lilies for a better flower display next year.
  • Dead-head annual bedding plants and perennials to encourage them to flower into the autumn and stop them self-seeding.
  • Cut back faded perennials to keep borders tidy.
  • As penstemon flowers fade, cut them back to just above a leaf to encourage more flowers.
  • Cut back herbs now to encourage a new flush of tasty leaves you can harvest before the frost.
  • Prune wisteria after flowering by removing all the whippy side-shoots from the main branch framework to about 20cm from their base (about five leaves from the main stem).
  • Trim any lavender plants after they've finished flowering to keep them compact.
  • Collect ripened seeds and store them for next year. Leaving some seed heads in place can be attractive and allows the plant to self-seed in the surrounding soil.
  • Mow meadows now to help scatter established wildflower seeds.
  • Take cuttings of your favourite tender perennials such as pelargoniums and fuchsia to propagate them for next year.
  • Finish dividing clumps of bearded Iris now, so they have time to form roots and flower buds for next year before the cold weather arrives.
  • Prune climbing roses and rambling roses once they've finished flowering (unless they’re repeat-flowerers in which case leave them).
  • Spray ground elder (and other perennial weeds) with a glyphosate-based weedkiller, the plants now have plenty of leaf surface area with which to absorb it.
  • Look out for symptoms of 'clematis wilt' including black discolouration on the leaves and stems of your clematis. Cut out any infected plant material and dispose of it in your household waste.


In the vegetable garden

The vegetable garden comes into its own in August, with plenty of delicious home grown produce to harvest. Here are some tasks to keep you busy this month:

  • Water sweetcorn plants regularly and feed with tomato food  to get the best cobs.
  • Apply a high-potash fertiliser such as tomato food once fruits start to form on peppers, cucumber and aubergine plants.
  • Continue to feed tomato plants with tomato food and remove lower leaves to help with air circulation and prevent disease. Pinch out the top of tomato plants to concentrate the growth into the fruit that has already formed. Aim to leave 5 or 6 trusses of fruit per plant.
  • Cut back herbs to encourage a new flush of tasty leaves that you can harvest before the first frosts. Dry or freeze excess herbs to use in the kitchen later.
  • Thin parsley to help it establish a good root system before winter. Leave 25cm between each plant.
  • Pinch out the tips of your runner bean plants once they reach the top of their support. This encourages side-shooting and more beans at a manageable height for picking.
  • Pinch out the growing tips of your aubergine plants once they have 5 or 6 fruits. Pick fruits while they’re young and shiny.
  • Limit the fruits on a squash plant to about three, but make sure these fruits are well established before pinching out the surplus.
  • Spring-sown carrots and beetroot will be ready to harvest now although they can be left in the ground to keep growing.
  • Continue to harvest second early potatoes now — perfect for salads!
  • Start harvesting your main crop potatoes as the leaves yellow and die back. Store your potatoes in hessian sacks which exclude light but allow ventilation.
  • Sweetcorn is ready to harvest when you can pop a corn with your thumbnail and the juices are milky.
  • Lift and dry onions, shallots and garlic once the foliage has flopped over and yellowed. Store them in onion bags to prevent mould developing.
  • Harvest French and runner beans little and often to prevent them from setting seed. Pick runner beans regularly to prevent them becoming stringy and to make room for developing pods. Leaving mature pods to set seed can prevent further flowers developing and reduce your crop.
  • Keep harvesting courgettes before they become too big!
  • Take cuttings of herbs such as rosemary, sage or mint now to bulk up supplies. Put cuttings in moist, well-drained potting compost (one part grit to one part compost) and place in a cold frame. Established clumps of chives can be divided now.
  • On a sunny day, collect seeds of herbs such as dill, bronze fennel caraway and chervil and dry in a warm spot out of direct sunlight. Chervil must be sown immediately.
  • Keep an eye out for potato and tomato blight and remove and destroy any affected plants immediately to prevent its spread.
  • Check for cabbage white butterfly eggs under brassica and leafy green leaves and squash any that you find. Alternatively use nematodes to kill the caterpillars.
  • Clear away any diseased and spent foliage around your veg plants to discourage pests and diseases spreading