September in your garden

It doesn’t feel like a month ago I was giving you tips for August and yet here we are in September already! The year is flying by.  Here at Thorngrove we’ve been busy potting up winter cyclamen, pansies and violas ready for the Autumn. So here are a few tips to keep you busy in the garden in September.


  • Now is the time to sow your Sweet peas in a cold frame or Greenhouse for early Summer blooms next year.
  • Sow other hardy annuals such as Calendula, Centaurea, Limanthes and poppies in situ.
  • If you sowed any spring-flowering biennials such as viola, Digitalis or Erysimum, earlier in the summer, they will now need planting out.
  • Its also a good time to plant out new perennials as the soil is still warm but moisture levels are increasing.
  • Don’t neglect your hanging baskets maintenance as a little dead heading, watering and feeding can keep them going until mid-autumn. After this, it’s best to re-plant as Winter/Spring hanging baskets with spring-flowering bulbs, winter heathers, trailing Ivies and Spring-flowering plants. (see our large range of Winter plants and Bulbs at Thorngrove!)
  • Continue to dead head plants such as Dahlias, Delphiniums and Penstemons to prolong the display and colour which will last well into the month.
  • Divide any over grown Alpines and Herbaceous perennials such as Crocosmias, this will invigorate them and improve flowering next year.
  • Take cuttings of tender perennials such as Pelargoniums and Osteospermums.
  • Plant spring flowering bulbs (again, we have a lovely our selection at Thorngrove)

Pests and Diseases

Here are a few pests and diseases to watch out for.

  • White rust on Chrysanthemums.
  • If you see distortion in your Phlox this could indicate the presence of Phlox eelworm. Phlox eelworm does not invade the roots, so you can clean up affected stocks by taking root cuttings, then growing the resultant plants in a different part of the garden.
  • Powdery Mildew can still be a problem in a dry and warm September. – you can find some prevention tips and treatments for this right here: 

Fruit and Veg

  • Pick your Autumn Raspberries
  • Dig up any remaining potatoes before slug damage spoils them
  • Cover leafy vegetable crops with bird-proof netting.


  • Start to reduce the frequency of your Houseplant watering


  • Net your ponds now before leaf fall gets under way




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Thorngrove Garden Centre

Thorngrove Garden Centre