Tomatoes growing in the green house

Your organic garden in September

September sunshine is special - golden and gentle. But the growing days are shorter, with dew drenched mornings and cool evenings. Now is the time to gather your harvest before frosts threaten. And save your seeds before winter sets in.

See below for advice on soil, vegetables, fruit, herbs and flowers as well as the greenhouse and conservatory, lawns and ponds. Plus What to sow and plant in September and Vegetable Growing Cards for advice.

Soil and composting 🔗


  • Use a low nutrient mulch such as leafmould or straw, or even newly fallen autumn leaves, on any bare areas.
  • If it's early in the month, sow some green manures such as winter vetch or grazing rye, to protect and improve any bare soil over winter.
  • Empty the compost bin by bagging up compost from the bottom of the bin/heap. Store it ready for use next spring. Now you are ready to start a new mix. See Home Composting.
  • If you have a worm bin, bring it under cover to protect against frost. See the members' factsheet on Worm composting.

Vegetables 🔗

  • See Harvesting and storage for tips - making sure that only perfect, non-bruised or damaged veg or fruit is stored.
  • Clear away diseased plant material ie blotched or mildewed leaves. Most can be composted, but if in doubt, dispose of via the green waste system.
  • Keep weeding to prevent weeds seeding.
  • Brassica whitefly can survive the winter on Brussels sprouts, broccoli, winter cabbage and kale. These tiny, white creatures fly up in clouds when the plants are disturbed. Their sticky honeydew often encourages black ‘sooty’ moulds to grow on leaves. Pick off infested lower leaves; the young whitefly ‘scales’ live on the underside of these. Spray both sides of remaining leaves with insecticidal soap if the infestation is bad, repeating two or three times if necessary.
  • Pick off any cabbage white caterpillars.
  • Leek rust, a fungal disease with red/orange pustules on the leaves, turns leaves yellow and stunts the plant's growth. There is little you can do to counter it, but the good news is that the leeks are quite safe to eat, just remove affected outer growth. See the members' factsheet on Leek rust.
  • Slugs can be a real problem in a warm wet autumn. Check slug traps daily, especially after damp weather. Nematodes will only work early in the month when soil temperatures are above 10°C.

Fruit 🔗

  • Scatter windfall fruit around the garden as food for wildlife. Plums are a favourite of butterflies - they adore the sugary juice.
  • Clear all weeds around fruit bushes and trees to prevent them seeding.
  • Remove nets from soft fruit to allow birds to clear up pests over the winter. Cultivate the ground lightly around plants to expose pests.
  • Order new fruit trees and bushes; bare-root plants will be ready for delivery in November. Choose varieties that will suit the site (wind, sun, soil type etc) and cultivars that are resistant to pests or diseases. See Fruit planting and care also the members' factsheet on Planting fruit trees & bushes.
  • After picking autumn-fruiting raspberries, do not prune. Wait until late winter/early spring to cut all the canes down to ground level. However, you can remove any weak or damaged canes of summer fruiting raspberries.
  • Complete pruning of stone fruits (including plums and cherries) by the middle of September to avoid silver leaf disease (Chondrostereum pupureum). Cut out all affected growth and any dead wood.

Herbs 🔗

  • Parsley, rocket and coriander can still be sown this month.
  • Cut herbs for drying and use throughout the winter.
  • Save seeds of your organically grown herbs for next spring. Make sure they are dry, then store in airtight containers in a cool place

Flowers 🔗

  • Remove dead and dying flower heads daily, to clear away potential sources of disease.
  • Don't cut back perennials too hard in the autumn 'clear up'. Hollow stems, tussocky plants and piles of leaves swept under a hedge make perfect overwintering sites for a huge number of beneficial creatures.

Keeping the growing area healthy 🔗

  • Brown Rot is an air borne fungal disease affecting pears, apples and plums. It produces concentric rings or white spots on the fruit and is spread by contact. Remove and destroy all infected fruit whether on the tree or on the ground.
  • Fix a sticky band of grease or glue around a fruit tree trunk to stop wingless adult winter moths getting up into a tree to lay eggs in the bark. Winter moth caterpillars will feed on the leaves, blossoms and young fruitlets during spring.


  • The warm days and cool nights of this month require careful management - remembering to open and close the door/windows.
  • Water plants less frequently, and avoid wetting the foliage. Damp foliage = fungal spore germination. Throw out any leaves that start to develop a grey fuzz, or become slimy and brown.
  • If you bring plants into the greenhouse/conservatory check thoroughly for pests. Look for mottled leaves that would indicate spider mite, and treat with an organic spray. Remove rolled and webbed leaves, they indicate tiny caterpillars lurking. Shake off the top centimetre of soil to clear out any pests near the surface and replace with a layer of grit. Next spring shake off the grit, and replace with some clean potting compost.


  • Clear out your pond of weed, overgrown plants and any dead foliage before hibernation starts. Leave all plant debris in a pile by the side of the pond for a couple of days to allow creatures caught up in the strands to crawl back to the water.
  • Early in the month, before heavy frosts set in, is also a good time to set up a pond. You can plant it up in Spring. See the members' factsheets Setting up a pond and Ponds: Maintenance and problems.

Lawns and hedges

  • Lawns can become very compacted during the summer so rake out any thatch, then aerate - either the whole lawn or just compacted areas.
  • Brush a soil conditioner, such as sieved leafmould, into the holes after aerating. Avoid any lawn food high in nitrogen at this time of year. It promotes growth at the wrong time.
  • To manage moss, poor drainage and other lawn problems see The organic lawn.
  • Leave some areas of grass long over winter. Many creatures will be hunting for overwintering shelter from now on.
  • Leave hedge trimmings tucked under the hedge, where they will provide the perfect hibernation site for a whole range of wildlife including hedgehogs and frogs.