Remove spent blooms now to encourage a fresh flush of colour before the first frosts
August is the perfect time to give flowering plants a little extra attention (even as scorching temperatures show no sign of dipping). While it can be tempting to leave faded blooms in place, removing them can encourage many plants to put their energy into producing fresh flowers, rather than seeds.
From colourful dahlias to pollinator-friendly cosmos, these are the plants worth deadheading this month for more flowers in the weeks ahead.
Bright dahlias are the stars of the late-summer garden, but regularly removing faded flowers will help keep them producing new blooms, rather than wasting nutrients on old flowers.
‘Cut old flowers down back to the main stem or next set of leaves, cutting at a slight angle so that water will not pool on the cut,’ explains Richard Barker, horticultural expert and commercial director of LBS Horticulture.
Check plants regularly and remove flowers as soon as they start to fade. Dahlias also benefit from consistent watering during dry spells, particularly when they are actively flowering.
Repeat-flowering roses can continue blooming well into autumn, but deadheading in August is key to encouraging another flush of flowers.
'Trim just below the old flower or back to the first set of leaves, but do not continue deadheading beyond August,' says Richard.
This is an important distinction, as pruning too late in the season can encourage soft new growth that may be vulnerable to frost. It’s also a good idea to feed them if they are still actively flowering, in order to support continued growth.
Also known as African daisies, Arctotis can produce an impressive succession of colourful flowers when faded blooms are regularly removed.
'Just cut back the spent flower stem to just above a leaf joint,’ says Nick Hamilton, owner of Barnsdale Gardens. ‘I like to cut back into the clump of leaves so that you don’t just see a whole load of cut stems.’
Arctotis thrives in a sunny, sheltered position and needs free-draining soil, making it particularly well suited to containers and warmer parts of the garden.
With their tubular flowers, penstemons are excellent late-summer plants and can provide valuable colour towards the end of the season.
'On faded flower stems, cut back to a healthy side shoot or pair of leaves,' Richard tells us. 'This will also help to keep the plant looking tidy instead of remaining dry and brown.'
Penstemons prefer a sunny position with well-drained soil. Avoid allowing the roots to sit in water and water newly planted specimens during dry spells. Then, a light trim after flowering can also help maintain a neat, compact shape.
If you're growing cosmos, August is a good time to stay on top of deadheading. These cheerful, daisy-like flowers can continue producing blooms until October if deadheaded.
'The new flowers can provide a supply of late-season nectar for bees and butterflies,' Richard adds.
Cut faded flowers back to the next leaf node or bud. If the entire stem has finished flowering, it can be removed completely to encourage new side shoots.
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