What to do in your garden in Setpember

September is generally a cooler month than August, however it is starting off very warm and the forecast suggests it might be drier than August was. If you have been growing fruit or vegetables this year you’ll be kept busy harvest the fruits of your labour. Now is also the time to start planting spring-flowering bulbs for next year. Make sure you make the most of and sunny days and the remaining warmth while you can this month!


  • Divide herbaceous perennials
  • Harvest autumn crops
  • Collect seed from perennials and hardy annuals
  • Cover ponds with netting before the leaves start falling from trees
  • Reduce the frequency of houseplant watering
  • Clean out cold frames and greenhouses in preparation for autumn planting
  • Plant spring flowering bulbs
  • September can often be warm so remember to keep watering
  • Keep weeding as most perennial weeds are susceptible to weedkiller this month

Fruit & Veg

  • Harvest fruit and vegetables as they are ready
  • Dig up remaining potatoes before slug damage spoils them
  • Cover leafy vegetable crops with bird-proof netting

This is the time of year to give your greenhouse and coldframes a good clean out. Once your tomatoes and other crops have finished, thoroughly cleaning your greenhouse helps prevent pests from making a home over winter. It also prepares the space ready for autumn planting.


  • Reduce the frequency of mowing
  • Now is a good time to lay turf or plant seeds
  • Aerate and apply a top dressing
  • Trees, shrubs & Climbers

  • Clip hedges before mid September – leylandi, lonicera, privet, hawthorn, beech and yew
  • Prune climbing roses and keep deadheading those still flowering
  • Trim lavender bushes lightly with hedging shears. Don’t be too aggressive, if you need to get drastic, leave it until spring
  • Now is the time to plant or move conifers and evergreens
  • Bulbs & Flowers

  • Now is the prime time for planting spring bulbs
  • If you want indoor bulbs for Christmas plant before mis September
  • Bring tender perennials into shelter
  • Deadhead spent flowers to keep the garden looking tidy
  • Support tall flowers now before the autumn storms arrive