September Gardening Calendar

September sees the beginning of autumn, although the days are still long and often remain pleasantly warm. Keep your garden interesting with Japanese anemones and the first asters, while regular dead heading will ensure ending summer displays stay beautiful.

Flowers and shrubs

  • Empty pots of faded early summer bedding and cut back annuals and perennials best their best, adding old plants and cuttings to the compost heap
  • Dig up tubers of dahlias, gladioli and begonias, clean them off and store them until spring in dry compost in a cool, frost-proof place. Alternatively, in milder areas, protect those left in the ground with a thick mulch of straw or bark
  • Take cuttings of your favourite roses, check for suckers and cut off any you find just below ground level, and prune back old rambling stems that carried flowers to prevent wind rock. Collect fallen leaves from around roses to reduce the risk of any diseases carrying over to next season
  • Lift and divide congested clumps of perennials; dig and pot up tender perennials in the greenhouse or conservatory to protect them over the cold winter months
  • Collect seeds and plant in compost immediately, or lay them out to dry and store in labeled envelopes
  • Take lavender cuttings by pulling off new shoots and inserting them in gritty compost
  • Take cuttings from pansies and violas
  • Fork over bare patches ready for planting spring bulbs - plant daffodil, hyacinths, crocus, fritillaries and other dwarf bulbs in pots and borders or to naturalise under trees
  • Plant out spring bedding, including wallflowers, forget-me-nots and pansies
  • Plant new climbers and shrubs into soil that's well dug over and enriched with compost
  • Sow sweet peas in pots and protect the plants in a cold frame over winter for bigger, earlier blooms next year - pinch out seedling tips for bushier plants and more flowers
  • Sow hardy annuals outside in borders for early flowers next summer

Fruit and vegetables

  • Keep picking summer-sown salads to prevent the plants running to seed
  • Harvest sweet corn, marrows, runner beans, haricot beans, globe artichokes, apples, pears, plums and gages as they ripen - store the best ripe apples wrapped in newspaper and placed in wooden fruit crates to keep during the winter
  • Dig up onions and main crop potatoes and lay them out in an airy space to dry before storing
  • Cut down the ferny shoots of asparagus to soil level
  • Clear crops once they've finished and fork over flower beds
  • Plant garlic cloves outside in mild areas or in modular seed trays ready to plant out later this autumn
  • Plant out spring cabbages
  • Sow broad beans and hardy peas for early crops next year and turnips for spring greens in March and April
  • Dig up strawberry runners and pot them up or plant new strawberry beds
  • Cover herbs like basil and parsley with cloches, or bring potted ones under cover into a porch or grow on the window sill to use in winter
  • Stake tall Brussels sprouts to stop them from blowing over
  • Wrap grease bands around the trunks of apples, pears, cherries and plums to trap the crawling female winter moth
  • If the weather turns cold, cut off whole trusses of unripe tomatoes from outside plants before they're hit by frost and ripen in a sheltered, sunny spot
  • Finish summer pruning trained forms of apple and pear trees, as well as out fruited blackberry stems
  • Harvest seeds from good varieties of beans, herbs and tomatoes that you've enjoyed this year
  • Net autumn raspberries and blackberries to protect them from birds
  • Lift and dry main crop potatoes and store in paper sacks in a cool, dark place
  • Vegetables to sow now include cress, endive, lettuce and salad leaves, Japanese onions, spinach, spring cabbage, spring onions, turnips for green tops, winter radishes

In the greenhouse

  • Ventilate the greenhouse on warm days but close doors and vents every evening to trap in the warmth
  • Remove shading paint and netting and scrub down the glass to let in plenty of light. Check your greenhouse heaters are in working order
  • Pot up tender perennials grown outside, such as fuschias, and bring under cover, along with pots of summer bulbs, late-flowering chrysanthemums, agapanthus, aeoniums, eucomis, peaches and nectarines when frosts are forecast
  • Take root cuttings from Japanese anemones and oriental poppies
  • Pot up rooted cuttings taken in summer and early autumn
  • Sow sweet peas in pots for early flowers next summer
  • Pot up prepared hyacinths into bowls for indoor displays
  • Plant Paper-White narcissi, freesias and dwarf bulbs, such as iris, crocus, chionodoxa and scilla, in pots
  • Take cuttings of succulents such as sedums
  • Water crops in pots and grow bags more sparingly but continue feeding weekly
  • Water dormant pots of cyclamen that were left to die down for the summer, and keep them in cool conditions
  • Stop watering pots of achimenes, gloxinia and tuberous begonias to let them die down completely before storing tubers in dry compost for winter
  • Let sweet peppers develop their full colour and size before picking
  • Pick remaining outdoor green tomatoes and lay out on staging to ripen
  • Insulate your greenhouse with bubble wrap for winter insulation
  • Check all plants for signs of pests and treat immediately

Lawn and trees

  • Rake autumn leaves, moss and thatch, fungi and mushrooms from lawns
  • Raise the cutting height of your lawnmower  and continue composting clippings
  • Improve drainage on compacted lawns by spiking the ground with a fork or aerator
  • Prepare bare patches of lawn or soil ready for sowing lawn seed or laying turfbut don't actually lay or re-sow until the damper autumn weather kicks in - seed should be sown evenly at 50g/2oz per square metre and soil should be lightly raked afterwards
  • Apply an autumn lawn feed to treat weeds, promote strong root growth and prepare the grass for winter. If it’s a late summer, delay this until there is plenty of proper rain and you can see the grass growing again
  • Trim conifer hedges to neaten their appearance and control their height
  • Plant new or move conifer hedges and evergreen shrubs and keep them well watered

General maintenance

  • Stretch netting across ponds or water features to stop autumn leaves falling in and rotting
  • Build a leaf bin out of wooden posts and chicken wire to collect autumn leaves and turn into leaf mould
  • Bulk up the compost heap with spent flower heads and stems from around the garden
  • Cut everlasting flowers and ornamental grasses to dry and use in displays indoors
  • Start watering houseplants less frequently and move them off very cold window sills at night
  • Top up bird baths regularly and leave out sunflower seeds for birds to feed on
  • Clean out water butts and check downpipe fittings are not leaking; collect sprinklers, drip-feed systems and other watering kit to store in the shed during winter; wrap insulation foam around outdoor taps and pipes
  • Protect large ceramic or delicate glazed pots from frost damage by wrapping them in bubble wrap or moving them into a shed or somewhere undercover during winter

Plan ahead

  • Install a water butt under the gutter of your greenhouse, shed or house to collect autumn rain fall
  • Order bare-rooted roses, shrubs, fruit trees and hedging to plant during autumn
  • If you haven’t already, quickly buy spring bulbs for autumn planting
  • Buy tulips now while they’re freshly available but hold off planting them until late October to November

Little green fingers

  • Get the kids involved with planting out spring bulbs - either in pots and borders or underneath trees in the lawn (which handily look best with a natural, haphazard pattern)
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