Practical gardening advice for UK gardens
What to do this month

August gardening jobs

August is a month of abundant harvests, mature borders and increasingly noticeable signs that the growing season is beginning to change. Hot, dry weather remains possible across the UK, although cooler nights and periods of heavy rain can become more frequent as the month progresses.

Regular harvesting, watering and deadheading keep productive and flowering plants performing well. There is also plenty to sow for autumn, winter and early spring, particularly salads, oriental greens and spring cabbage. As spaces appear after crops are cleared, bare soil can be covered with green manures. This is also an important month for collecting seed, taking cuttings and preparing plants for the months ahead.

UK conditions vary. Adjust timings for your local weather, soil and exposure.

Key gardening jobs

  • Water containers, vegetables and newly planted trees and shrubs thoroughly during dry periods.
  • Feed flowering containers and hanging baskets where plants are still growing strongly and producing flowers.
  • Deadhead dahlias, roses, penstemons and bedding plants regularly to prolong flowering into autumn.
  • Collect ripe seed from suitable garden plants on a dry day and store it somewhere cool and dry.
  • Remove weeds before they flower or set seed, paying particular attention to recently cleared vegetable beds.
  • Sow green manure over empty vegetable ground that will not be replanted immediately.
  • Lift rooted strawberry runners and plant them into prepared soil or pots to establish new plants.
  • Keep ponds topped up during dry weather and ensure wildlife can enter and leave the water safely.

What to sow and plant

  • Sow winter lettuce, rocket and other hardy salad leaves outdoors for autumn and winter picking.
  • Sow spring cabbage outdoors or in modules for planting out once seedlings are large enough.
  • Sow pak choi, mizuna and other oriental greens outdoors for autumn harvesting.
  • Sow spinach, perpetual spinach and chard outdoors for later crops where conditions remain suitable.
  • Sow winter radish, turnips and kohl rabi outdoors for harvesting later in the season.
  • Sow autumn onion seed outdoors in suitable areas, adjusting timing to local climate and variety.
  • Sow hardy annual flowers outdoors towards the end of the month for earlier flowering next year.
  • Plant autumn flowering bulbs such as colchicums and autumn crocuses as soon as available.

What to prune and harvest

  • Summer prune wisteria by shortening long new shoots to around five or six leaves from the main framework.
  • Prune rambling roses after flowering where necessary, removing some older flowered stems and tying in strong replacements.
  • Lightly trim lavender after flowering without cutting deeply into old woody stems.
  • Cut old summer fruiting raspberry canes to ground level once all fruit has been harvested.
  • Harvest sweetcorn when the tassels have turned brown and the kernels release a milky liquid when tested.
  • Lift onions and shallots once their foliage naturally begins to die back, drying the bulbs thoroughly before storage.
  • Harvest maincrop potatoes as plants mature, particularly where slug damage or prolonged wet weather threatens the crop.
  • Pick tomatoes, cucumbers, courgettes, beans and other productive vegetables frequently to prevent crops becoming over mature.

Problems to watch

  • Watch tomatoes and potatoes for blight during warm, humid weather and remove affected material promptly.
  • Check cucurbits and other susceptible plants for powdery mildew, particularly during dry conditions.
  • Maintain steady watering of tomatoes to reduce problems with fruit splitting and blossom end rot.
  • Inspect brassicas for cabbage white caterpillars and check protective netting for gaps.
  • Watch ripening plums, apples and other fruit for wasp damage and remove badly damaged or rotting fruit.
  • Check roses for black spot and remove heavily affected fallen leaves from around plants.
  • Watch container plants for vine weevil damage, especially where otherwise healthy plants suddenly wilt or become loose in their pots.
  • Check beans, cucumbers, celery and other moisture demanding crops for drought stress during prolonged dry spells.
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