September is usually a good month weather-wise, especially as at the time of writing some forecasts were predicting that the heatwave will continue late into the month! The evenings haven’t drawn in too much, and the dew in the morning gets heavier and turns the spiders webs into crystal strands.

This is a good time of year to review your herbaceous borders before all the plants die back. Some plants will need to be lifted and divided, and some will need replacing or moving to a different position. If something is disappointing, don’t put up with it year after year – get rid of it and get something else!

Most herbaceous plants need dividing up every three to five years, as they start to get too congested and don’t flower as well as they used to. This work can be undertaken in autumn when the soil is moist and the weather is kind.

Perennials are perfect to plant in your border

Chop dug-up clumps of perennials and keep the young offshoots from the sides, discarding the old woody centre bits. Replant in soil to which fresh compost, bonemeal, etc. has been added. Leave grasses, silvery foliage plants and late-flowering plants until spring to sort out. You can also pick up some perennial bargains from your local nursery or garden centre, which they’ll want to get rid of in order to make room for new stock. These are perfect to plant in your border now so that they are ready to do their thing next year!

Another group of plants to think about including in your garden are the herbaceous clematis. These plants are invaluable at this time of the year, and as they are non-clinging, they wind their way through the borders, sprinkling their pretty flowers amongst the other border plants and lifting the whole display. Try ‘Arabella’ with its stunning purple/blue flowers, which will keep flowering from June to September, and actually does very well in a pot if you are short of space.

Colchicums make a lovely late display

Now is also a good time to plant Colchicums (autumn flowering crocuses). They like sheltered but sunny positions under trees – if too exposed they get beaten down by wind and rain. They look like crocus but have six anthers instead of three, which crocus have. You buy them as dry corms and arrange in small groups of seven or more where they will be readily seen in the autumn and will make a lovely late display. A word of warning – all parts of the colchicum plant are poisonous so be sure to wash your hands quickly after handling!

To keep your garden wildlife happy as autumn and winter approach, cover small ponds with netting to keep the falling leaves out as the trees start to turn. I usually leave a passage through for the frogs and toads so they don’t get all caught up!