Sowing and planting
Plant wallflowers, forget-me-not, Bellis, Primula, Viola (including winter pansies) and other spring bedding plants in prepared ground or pots.
In mild areas, it is still just possible to sow hardy annuals outside, to overwinter for a display next year.
Continue to plant spring-flowering bulbs.
Now is also good time to plant new herbaceous perennials, as the soil is still warm, but moister than it was during the summer.
Lily bulbs can be planted up in pots this month.
Cutting back, pruning and dividing
Cut back faded herbaceous perennials and add to compost heap.
Lift and divide poor flowering or overcrowded herbaceous plants.
Maintenance
Wait for first frosts to hit dahlias and cannas before lifting the tubers or rhizomes. They may overwinter in the ground in warmer regions if covered with a protective layer of straw or bracken, but flowering may be late and/or poor next year.
Lift tender bulbs if you live in a cold area; Galtonia and Tigridia bulbs, for example, need lifting and storing over the winter.
Any remaining summer bedding plants struggling on in milder areas are best cleared and replaced, for a fresher display.
Don't neglect hanging basket maintenance - a little deadheading, watering and feeding can keep them going until mid-autumn. Once they are past their best, re-plant with spring-flowering bulbs, winter heathers, trailing ivies and spring bedding plants.
General maintenance
Raise patio containers on to bricks or purpose-made pot feet to avoid them sitting in water during the winter.
Move alpine troughs to a covered porch or lean-to to protect them from the rain.
Pick over alpines regularly, removing any autumn debris and covering died-back patches with extra grit to encourage their re-growth.
Make sure you have finished bringing all tender plants into the heated greenhouse or conservatory for the winter.
Remove stakes and other supports as herbaceous plants die down for the winter.
Check any bulbs being forced in darkness. If they show signs of top growth and have a healthy root system when knocked out of the bowl, bring them into a cool, light room to induce flowering.
Planning ahead
Continue collecting and storing seed from perennials still forming seedheads.
Pest and disease watch
Check chrysanthemums regularly for signs of white rust and treat where necessary.
Discoloured leaves on herbaceous plants such as Chrysanthemum, Anemone and Penstemon, could be leaf and bud eelworm.
Grey mould (Botrytis) can be problematic in wet weather. Remove affected leaves and other parts as soon as the symptoms are seen.
Powdery mildew may still be a problems in dryer, warmer regions having a good 'Indian summer'. It is best to control this disease by cultural methods or by cutting back fading growth, rather than by spraying, which is less effective at this time of year.
Avoid feeding plants late in the season, as this will encourage soft, sappy growth that is more vulnerable to damage by frost and by wet, and can encourage fungal diseases to develop.
Digging the soil, especially bare patches or newly cultivated land, will expose many pest larvae and eggs to birds and frosts, as well as clearing weeds and improving soil structure. Don't leave soil uncovered for too long, however, as it runs the risk of erosion and washing away of valuable nutrients. Black polythene sheeting will protect it in the absence of planting or mulch.