August in the flower garden can be a bit of a challenge. Summer is well under way and many herbaceous plants have reached their optimum flowering peak. You could be forgive for thinking that this month is a month of tidying up. However, with a bit of forward planning and some gentle encouragement you can design a planting scheme that will ensure that you have plants that flower well into the fall as well as encouraging those earlier flowering ones to produce second flushes. So in-between relaxing and enjoying summer in your garden, take a moment to check this short reminder of things you should be doing in the flower garden during August.
Once rambling roses have finished flowering prune them back, removing shoots that have finished flowering. Continue to deadhead herbaceous plants such as lady’s mantle, nepeta and delphiniums. Trim back any fading perennials and put the cuttings onto the compost heap. To ensure the continuation of tender perennials, take cuttings and bring them on in the greenhouse. Also take cuttings of lavender, sage and perennial wall flowers. Take cuttings of shrubs such as heather, geranium, hydrangea and fuchsia.
Buy bulbs for fall planting such as tulips, alliums, iris and crocus. Narcissus bulbs can be planted out now to flower next spring. Plant the rest towards the end of the month except for tulips which shouldn’t be planted until at least November. Remove any leaves on roses that show signs of blackspot and continue to deadhead as long as you don’t want the plant to produce hips in the autumn. Clear away any spent bedding plants and replace with forget-me-nots and wallflowers. Deadhead dahlias and they will continue to flower well into fall. Once lavender has finished flowering, remove the flower heads and trim lightly into shape.
Collect seed from those perennials that have finished flowering and store in labelled paper envelopes until you are ready to sow them next spring. Towards the end of the month is a good time to plant shrubs such as conifers and hedging plants. Prepare the soil first by digging in plenty of well rotted manure or compost. Make sure any tall growing late perennials such as chrysanthemums are staked to plant supports.