Practical gardening advice for UK gardens
What to do this month

September gardening jobs

September marks the change from summer into autumn. Harvests are still coming thick and fast, but cooler nights and increasing rainfall make this an excellent time to plant, divide established perennials and prepare the garden for the months ahead.

Keep watering newly planted trees, shrubs and perennials during dry spells, and adjust each job to suit your local weather, soil and exposure.

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

Key gardening jobs

  • Plant daffodils, crocuses and other spring-flowering bulbs
  • Divide congested herbaceous perennials once the soil is moist
  • Keep watering recently planted trees, shrubs and perennials during dry weather
  • Collect ripe seed from healthy annuals and perennials
  • Net ponds before heavy leaf fall begins
  • Clean greenhouses and cold frames ready for autumn use
  • Cover brassicas and leafy crops with secure bird-proof netting
  • Prepare a leaf-mould area and keep adding suitable material to the compost heap

What to sow and plant

  • Sow spinach, winter lettuce, rocket and other hardy salad leaves
  • Plant overwintering onion sets and protect them until rooted
  • Plant out spring cabbages and protect them from pigeons
  • Sow hardy annuals where they are to flower
  • Sow sweet peas in a cold frame or unheated greenhouse
  • Sow winter green manures on empty vegetable beds
  • Plant new hardy perennials while the soil is warm and moist
  • Plant new strawberry beds or rooted runners

What to prune and harvest

  • Harvest apples and pears as they ripen
  • Lift remaining maincrop potatoes before slug damage increases
  • Harvest autumn raspberries, plums, beans, courgettes and tomatoes regularly
  • Cut out fruited blackberry and hybrid berry canes, then tie in the new growth
  • Continue deadheading dahlias, roses and penstemons
  • Remove collapsed or diseased perennial growth but leave healthy stems and seedheads for wildlife
  • Cut down asparagus foliage only after it has turned brown
  • Harvest pumpkins and winter squash once mature and before frost threatens

Problems to watch

  • Check potatoes and tomatoes for signs of blight
  • Watch for powdery mildew during warm, dry weather
  • Maintain even watering to reduce split roots and tomato ripening problems
  • Protect brassicas and newly planted onion sets from pigeons
  • Check potatoes and low-growing crops for slug damage
  • Remove badly diseased fallen leaves rather than leaving them around plants
  • Check newly planted specimens for drought stress even when the weather feels cooler
  • Identify fungi carefully because many autumn toadstools are harmless
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Guides for your garden

Month tags describe the topic, not the publication date. Wider seasonal and recent articles have their own labels when more guides are needed.