High Days and Holidays

While the city streets in August may be relatively quiet due to the summer holiday exodus, the garden is as busy as ever.

August can be a conflicted time in the garden. While many mid-summer plants have passed their best and are looking a little ragged around the edges, and the stars of autumn are still waiting in the wings, there is still plenty of life and light left this year for the garden to put on a lovely late-summer show.

Planning for constant summer flowering

Purple top vervain, Verbena bonariensis

Purple top vervain, Verbena bonariensis, Hans Braxmeier, CC0

Many plants are still going strong and a clever gardener will have planned for a succession of plants to flower right through the seasons, providing distraction from the inevitable gaps as individual plants emerge at different rates and naturally begin their annual decline.

Late-summer perennial star performers include the elegant, often drooping, daisy like flowers of the coneflower, Echinacea sp; the tall and airy purple sprays of the purple top vervain, Verbena bonariensis and the vivid, trumpet like flowers of Monbretia, Crocosmia. Shrubs in full bloom this month include the large, blooming clusters of the butterfly bush, Buddleja; the simple but cheering saucer like flowers of the mallow, Lavatera, and the fluffy and cloudy plumes on the aptly named smoke bush, Cotinus coggygria.

Wildlife in the garden

Painted Lady Butterfly

Painted Lady Butterfly, Susann, CC0

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 a late nectar energy boost. Other plants such as teasel, Dipsacus fullonum and Sunflowers, Helianthus annus, have seeds ripening for birds to stock up on energy as we head toward Autumn.

Keep a weather eye out

Hallelujah - it has been raining hard in the UK recently, giving the garden a much needed soaking that watering with a hose simply cannot achieve. However, it is still important to keep an eye out on 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 the mid-summer drenchings of late.

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. Save water, money too if you are on a meter and gain a credit in the bank of environmental awareness and sustainability.

Slugs and bugs

The rain also flushes out slugs and snails from hiding and many will be brazenly stepping (slithering?) out in full daylight into the soggier conditions in the garden. Take the opportunity of their increased visibility to collect them up for disposal – leaving a few for any resident amphibians and birds to snack on perhaps. Do not feel too bad about it for it is believed that the average British garden might contain 20,000 slugs and snails, many of which are out of site and under the soil. Dog owners beware as some snails carry a parasite that is harmful and sometimes fatal for undiscerning dogs that fancy a slimy snack.

A regular hosing of paths and foliage for those lucky enough to have a greenhouse can help to keep red spider mites at bay as this sap–sucking pest does not like damp conditions. Many garden plants are also vulnerable to the red spider mite and it will help to spray them down too during hot and dry spells. A gorgeous honey spurge, Euphobia mellifera, in my garden has fallen victim to these tiny mites, which have left their characteristic footprint of fine webbing and mottled leaves.

I am hoping to have caught my invasion before it is too late and will release a platoon of Phytoseiulus persimilis mites in a sheltered position around the base of the Euphorbia to attack and feed on the invading red spider mites. This approach of using biological controls includes releasing predatory mites, midges or beetles around infected plants. These are available by mail order and are effective and far more preferable to use than chemical control.

Use grasses

The judicious planting of ornamental grasses across a bed can disguise the tatty foliage and gently absorb the spaces left behind by their declining neighbours. Species such as the elegant, arching, orange hued pheasant’s tail grass, Stipa arundinacea and the swirling, tufty leaved Mexican feather grass, Naselle tenuissima, will swirl and twirl and soften any scheme and disguise the inevitable gaps created by emergent and declining foliage. Both are in flower in August adding a bouffant plumpness to this overall winning effect. As wintergreen plants, they also have a long seasonal interest and look good well into winter.

Lavender, Lavandula

Lavender, Lavandula, Hans Braxmeier, CC0

Prune lavender

Prune lavender after the blooms have faded by removing old flowering spikes back into about 2-3 cm green growth whilst maintaining the form of the plant. Do not cut into old wood as this will not regrow new stems next season. The faded blooms are still fragrant and worth saving for posies or displays. Moths are deterred by the scent of lavender so it may be worth hanging some close to favoured natural fabrics.

Prune Wisteria

If it wasn’t done last month August is time to complete pruning wisteria. Cut back the lateral and side shoots that have grown since spring to just 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. Tie in the stems to their support as necessary. Be careful on the higher branches and hire in professionals if unsteady on a ladder.

Plan ahead

It is hard to believe that summer is drawing to a close, but there is no harm in sourcing spring flowering bulbs such as daffodils, crocus, hyacinth and allium, which will need planting in early – mid autumn. There will be more on how to plant bulbs in the September blog post. For now, keep an eye out for gaps that can be plugged with them but do not dwell too much on the decline of summer while it is still here – there is plenty of time for that later!

Jobs for August

  • Water plants well at least once a week during periods of dry weather. A good soaking is better than a quick spray. 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.
  • 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.
  • Keep ponds topped up with harvested rain water or on a fine spray setting with a hose. Clear dead foliage from the pond to avoid it building up to a stinky sludge.
  • Deadhead plants such as repeat flowering roses and hardy geraniums to encourage further blooms this season.
  • 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.
  • 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 and growing and feeding practices.
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.