Sultry August

Sultry summer days, heat haze, parched grass or torrential storms, the high summer mix. Swallows and house martins are beginning to gather in flocks before leaving for their migration to Africa to avoid the European winter. Lammas, on the 1st of August, traditionally celebrates the grain harvest and offerings of bread to the pagan gods. Meadow plants too have ripened seeds and are ready to cut, to be left on the ground to dry until the seeds fall, then raked up and removed to reduce fertility and allow the recovery of the sward for the following year. Hedgerows and trees are full of ripening fruits, berries and nuts; autumn is approaching. In dry weather the August garden can look listless. Earlier summer plants are on the wane and those that flower into the autumn may not yet have bloomed, but there are repeat flowering plants and drought tolerant species bringing colour and interest to the fading greens of late summer.

In the garden

Purple fountain grass (Pennisetum x advena 'Rubrum')

Purple fountain grass (Pennisetum x advena ‘Rubrum’), Mokkie,, CC BY-SA

Many ornamental grasses look their best in August, their tall flowering spikes reaching up from a leafy base to form gently swaying translucent curtains. They have an architectural form that remains for most of the year, creating texture, depth and movement in a garden. In late summer the seed heads shimmer in bright light glowing gold, pink and silver in the sun. Stipa gigantia has clumps of grey green leaves, tall stems and oat like, golden seed heads. Pennisetum x advena ‘Rubrum’ with its purple tinged leaves has large, soft, bottlebrush like flowering heads of pink and gold. Molinea caerulea subsp. arundinacea ‘Transparent’ has ribbon like leaves, tall stems and tiny seeds creating a gauzy curtain which dances in the breeze.

Monbretia (Crocosmia ‘Spitfire’)

Monbretia (Crocosmia ‘Spitfire’), Mike Peel, CC BY-SA

There are other late-summer perennials that bring colour to the garden in August. These include the Mediterranean species such as lavender, rosemary, oregano and hyssop that are drought tolerant and thrive in the sun. Many daisy like, prairie plants are also in flower. Vibrant sneezeweed, Helenium with rich, warm coloured petals and contrasting rounded centres, bright Rudbeckias, many with dark centres and yellow petals that lighten up the borders and the elegant, often drooping, flowers of the coneflower, Echinacea sp. Amongst these the tall and airy purple sprays of the purple top vervain, Verbena bonariensis and the vivid, trumpet like flowers of monbretia, Crocosmia and the perfect, deep blue, spiny, spherical flowers of the globe thistle, Echinops. Shrubs in full bloom this month include the large, spires of the butterfly bush, Buddleja; the simple, soft, saucer like flowers of the mallow, Lavatera, and the cloudy plumes on the smoke bush, Cotinus coggygria above its brilliant deep purple leaves. The vigorous viticella clematis group, flower from July to September, scrambling through shrubs or covering walls and trellises with their rich colours. They are native to Spain and southern Europe so love the sun. Clematis ‘Etoile Violette’ has deep purple flowers, Clematis ‘Madame Julia Correven’ with rich ruby flowers and wine red Clematis ‘Royal Velours’ all bring an abundance of colour.

Other species offer repeat flowering, so it is possible to plan for a succession of plants to flower right through the summer, providing distraction from the gaps as individuals emerge at different rates and naturally begin their annual decline.

Small tortoiseshell butterfly

Small tortoiseshell butterfly, Rob Young, CC BY-SA

These late-summer flowers are essential to pollinators and other nectar seekers. Late flying butterflies such as Painted Ladies and Small Tortoiseshells, the Hummingbird Hawk moth, a day flying moth, and dusk flying moths all appreciate the provision of late nectar. Some plants such as the teasel, Dipsacus fullonum and sunflower, Helianthus annus, have seeds ripening for birds to stock up on energy as we head toward autumn.

With long periods of drought it is still important to keep an eye out for those areas in the garden that even a hard rain may not reach. These rain shadows may be under densely canopied trees or shrubs or against walls and fences, and the plants growing in them may have missed out on any rain that is offered.

Keeping plants well irrigated is essential to their survival and also reduces powdery mildew, which is particularly aggressive with plants that have been allowed to dry out. No matter how hard and long the rains falls, containers need regular irrigation because rain is more likely to drain off the plants’ foliage than into the container and their soil can dry out very fast. Consider reusing grey water from baths or fill a bucket while waiting for the shower water to heat up to save water. And don’t forget birds and mammals, these too need access to water in dry weather.

Cut back repeat flowering plants

Geranium 'Rozanne'

Geranium ‘Rozanne’, Dominicus Johannes Bergsma, CC BY-SA

Many cottage garden plants are repeat flowering. Hardy geraniums such as ‘Rozanne’ and ‘Patricia’, delphiniums, centarea, Salvia nemorosa ‘Caradonna’ and lupins can be cut back after flowering as the stems start to fade. If they are then watered well and given a good liquid feed, a second flush of leaves and flowers will emerge in late summer.

Make your own liquid fertilizer

Making your own liquid fertilizer is cheap and easy. All you need is a bucket, water and vegetable waste, weeds or high nutrient plants like nettles or comfrey. You will be using waste plant material and reducing the environmental costs of chemical fertilizers. Essentially just put the plant material in a bucket, fill the bucket with water and leave to steep for around 4 weeks. The dark liquid can become smelly so leave the bucket outside. Once it is rich and brown pour it onto your plants or crops.

Plant out gaps

Canna lily

Canna lily, Mokkie, CC BY-SA

If there are gaps in your beds or borders, after other plants have died back you can move tender or greenhouse plants such as perlagoniums, canna lilies or dahlias out into the garden to fill them. Those that were inside should be kept in the shade for a few days to adapt to the heat and higher levels of light before being placed in the sun. Ornamental edibles can also be used. Small brassicas, cabbage, broccoli and kale, oak leaved lettuce or mustard greens can be bought cheaply and grow quickly to fill the gap and in addition provide a crop later in the year.

Mass pots of a splash of colour

If the garden is generally looking faded and dull a strong splash of colour in one area will help lift it. Mass pots and containers full of flowers to brighten the most heavily used areas. Many tender perennials and summer bedding plants are now being sold off cheaply in garden centres to make way for the new autumn stock. These cheap plants are likely to last up to November if watered, deadheaded and feed through the autumn.

Leave seedheads and hips as winter fodder for wildlife

Brown and fading seed heads, orange and red rose hips bring an autumnal feel to the garden. Many create a framework of persistent spires, pods and spikes and seed heads that can give interest well into the winter. In the past it was normal to deadhead and tidy the garden as the summer progressed but if you prefer to garden with nature, the drying stems and fruits can give a further season to your plants and provide a welcome source of food for garden creatures. The fading flowers, ornamental grasses and perennials take on tints of gold, russet and silver, transformed when back lit by the lowering sun and can be especially magical, shinning silvery white, in a frost.

Gardening tasks in August

  • Water plants well at least once a week during periods of dry weather especially recently planted trees and shrubs. Distressed plants can recover after a thorough soaking. Container grown plants are likely to require more watering and be sure to water these so that the water just dribbles out of the bottom of the pot.
  • Source spring flowering bulbs such as daffodils, crocus, hyacinth and allium for planting in autumn.
  • Sow hardy annuals to overwinter in beds and borders at the end of the month.
  • Prune lavender by removing old flowering spikes back into 2-3 cm of green growth whilst maintaining the form of the plant.
  • Prune Wisteria by cutting back the lateral and side shoots that have grown since spring to just a above the fifth or sixth set of leaves on each stem – or back to the appropriate shoot it the stem has grown to its allotted space.
  • Prune those climbing and rambling roses that do not flower repeatedly and have no ornamental and edible hips.
  • Mow or scythe summer flowering meadows, leave the plants to dry for a few days before collecting. The seed will fall from the plants but removing the rest keeps the soil low in fertility which is what wild flower meadow prefer. If there is any chance of hedgehogs in your meadow area first mow to knee height, check the ground and remove any hedgehogs to a safe place before the final, lower cut.
  • Keep ponds topped up with harvested rainwater. Clear dead foliage from the pond to avoid it building up to a sludge and increasing the fertility levels, this will cause algae to grow and cloud the water.
  • Keep bird baths full and leave out water for any mammals that may visit your garden.
  • Deadhead plants such as repeat flowering roses and hardy geraniums to encourage further blooms this season.
  • Trim hedges after checking for late nesting birds.
  • Collect seeds for next season. Store seeds in a cool, dry and dark place. Label the containers with the plant name and date of collection.
  • Have a general tidy of dead and damaged foliage on plants throughout the garden.
  • Feed pots and other containers to keep them flowering.
  • Keep an eye out for pest and diseases. Check for unusual scarring, stickiness, webbing, curling, lumps or discolouration on stems, leaves and flowers. Remembering to check under the leaves too. Look for the presence of insects, larvae or pupae, which appear static or in abundance. Identify if there is problem with a pest of a disease and remedy as appropriate using organic and biological methods. Bear in mind that many problems with pest and diseases can be prevented and controlled by good garden hygiene, growing and feeding practices. Pests can also provide food for birds, frogs and beneficial insects so only treat if necessary.

Relaxing reading

Green Escapes: The Guide to Secret Urban Gardens

Toby Musgrove

Use urban gardens from around the world as inspiration for your own patch; from pocket gardens to community spaces, tower blocks to extensive private gardens.

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What Nature Does For Britain

Tony Jupiter

Tony Jupiter looks at the value of nature and at how environmental problems can be solved using natural solutions.

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Garden and wildlife events

Queen Elizabeth Hall Roof Garden

The roof garden has wildflowers, fruit tress and edible gardens, alive with insect activity and with extensive views of London and the Thames. The garden is maintained by a group of volunteers using gardening to improve their mental health and well being following periods of homelessness and addiction. Admission is free.


Until 30 September 2018, 10am-10pm


Queen Elizabeth Hall, Southbank Centre, Belvedere Road, London SE1 8XX

Learn more >

Hyde Hall Flower Show

Specialist nurseries, expert advice and a permanent drought tolerant garden, buzzing with bees and butterflies.


1-5 August 2018, 10am-5pm


RHS Garden Hyde Hall, Creephedge Lane, Rettendon, Chelmsford, Essex CM3 8RA

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Summer Plant Walk: Tower Hamlets Cemetery Park

Lead by botanist and plant folklorist Roy Vickery, discover the biodiversity of a London Cemetery.


5 August 2018, 2.30pm-4.30pm


Tower Hamlets Cemetery Park, Southern Grove, London E3 4PX

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Catriona Andrews


Catriona is a landscape designer and environmental educator. Her work combines naturalistic planting and sustainable practices to create spaces that are sensitive to the environment and welcoming to wildlife. She designs private gardens, community gardens and public spaces and leads courses and workshops on garden and planting design and the environment.

Elaine Hughes


Elaine is an RHS Gold Medal award winning landscape designer with a special interest in creating beautiful and functional spaces that are also as biodiverse and sustainable as possible. She has designed a wide range of projects including private gardens, community gardens, public areas, schools and community sites.