By the end of August, the garden is beginning to show what has worked and what has struggled. Some plants are still flowering strongly, some have useful seedheads or foliage, and others have clearly run out of steam. This is a good moment to walk around with a practical eye and decide what to keep, what to cut back, and what to replace.
What to keep for late-season interest
Keep anything that still adds structure, colour, or wildlife value. Dahlias, salvias, penstemons, rudbeckias, echinaceas and hylotelephiums can all carry the garden into September if they’re healthy and watered. Deadhead where more flowers are possible but leave some later seedheads where they add shape or food for birds.
Ornamental grasses are worth keeping standing. Their flowerheads catch low light beautifully and will continue to give movement as the garden shifts into autumn. Eryngiums, alliums, teasels and poppy seedheads can also earn their place, especially in naturalistic borders.
What to cut back now
Cut back plants that have collapsed, mildewed badly or finished untidily. Hardy geraniums and nepeta often respond well to a trim, producing fresh foliage and sometimes another flush of flowers. Remove yellowing leaves from daylilies, hostas and tired perennials, but do not strip borders bare for the sake of neatness.
Where stems have flopped over paths, cut them back or tie them in. Good late-summer maintenance should make the garden easier to enjoy, not leave it looking empty.
What to replace for autumn colour
Containers are usually the first place to refresh. If bedding has stopped flowering, become leggy or looks beyond rescuing, it is worth refreshing the compost and replanting. Violas, pansies, cyclamen, heucheras, compact grasses and evergreen herbs can bring a more autumnal feel whilst still looking attractive now.
In borders, note gaps before the foliage disappears. You may not need to fill everything immediately, but this is the best time to see where stronger late-season plants are needed. Japanese anemones, asters, hylotelephiums, grasses and autumn bulbs can all help extend interest.
Judge what has earned its place
A plant has earned its place if it gives more than one moment of interest. It might flower well, attract pollinators, offer foliage, hold seedheads, or give winter structure. If it only looks good for a fortnight and then leaves a mess, it may need better companions, a new position or to be replaced with something more reliable.
At summer’s end, the goal is not to make the garden spotless. It is to edit thoughtfully, keeping the plants still working, cutting back what has finished, and replacing what no longer adds to the display. This way, the garden moves into autumn with purpose rather than simply fading away.
Focus Plant - Caryopteris
Caryopteris is the shrub that seems to arrive just when the garden needs a lift. Its soft, blue-purple flowers appear in late summer and early autumn, bringing a fresh note to borders after many earlier shrubs have finished. The leaves are usually grey-green and aromatic, giving the plant interest even before the flowers open.
It is particularly useful in sunny borders, gravel gardens and wildlife-friendly planting, where its flowers attract bees and other pollinators. Caryopteris × clandonensis ‘Heavenly Blue’ is a well-known choice, with bright blue flowers and a compact habit. ‘Dark Knight’ has deeper blue-purple flowers, while ‘Hint of Gold’ offers golden-green foliage with blue blooms for extra contrast.
Caryopteris grows best in full sun, in free-draining soil. It dislikes cold, wet ground, especially in winter, so avoid heavy soils that stay waterlogged. It can also work well in containers, provided the pot drains freely, and plants are not left sitting in wet compost. At the end of August, care is mainly about enjoying the flowers and keeping container-grown plants watered during dry spells. Avoid hard pruning now. Caryopteris flowers on the current season’s growth, so cut it back in spring to encourage strong new stems and a better late-summer display.
Fun fact: Caryopteris is often called bluebeard, a name inspired by the fluffy clusters of blue flowers that appear around the stems.
Gardening Jobs
1. Plant colchicum bulbs now for late-season colour. These autumn-flowering bulbs can appear quickly after planting, producing goblet-shaped blooms before the leaves emerge in spring. Choose a sunny or lightly shaded spot with fertile, well-drained soil, and wear gloves when handling the bulbs.
2. Sow winter purslane for cold-season salad leaves. Also known as miner’s lettuce, it is hardy, mild-flavoured and useful for winter pickings. Sow in late summer, either direct or in trays, then keep seedlings watered while they establish.
3. Water cranberries and lingonberries with rainwater during dry weather, especially if they are growing in containers. Both are acid-loving plants, so avoid hard tap water where possible. Keep the compost consistently moist, but do not leave pots sitting in waterlogged soil.
4. Remove badly mildewed courgette leaves to improve airflow and make harvesting easier. Powdery mildew is common later in the season, especially in warm, dry conditions. Take off the worst leaves, but leave plenty of healthy foliage to keep feeding the plant.
5. Check bay, box and laurel for scale insects. Look for small, shell-like bumps on stems and leaf undersides, along with sticky honeydew or black sooty mould. Light infestations can often be wiped away by hand before they spread further.
Did you know?
Foxgloves are cleverly shaped for bumblebees. Their tubular blooms act like little tunnels, with spotted throats guiding visitors towards nectar. Fine hairs inside help deter smaller insects, favouring larger bees that can brush against the pollen.
Walnuts, especially black walnut, are famous for juglone, an allelopathic compound found in roots, leaves and nut husks. Sensitive plants growing nearby may become weak, yellow or stunted, so choose planting companions carefully.
Asters have wonderfully poetic old names. “Starwort” reflects their starry daisy-like flowerheads, while “farewell to summer” suits their late-season colour, arriving as the garden begins to turn towards autumn and supporting late-flying insects.
Each visible lithops “stone” is really a pair of swollen leaves. The flattened tops contain translucent windows, letting light reach internal photosynthetic tissue while the plant stays disguised as a pebble, helping it cope in harsh, bright habitats.
