Jobs to do in the garden in August

Any garden can start to look a little dusty and dry now, with leaves falling naturally around the borders. It’s best to gather them up to help prevent pests and disease building up. “Some weeds are quite attractive and are beneficial to wildlife, so if you leave the odd patch here and there, it’s not a bad thing,” adds RHS Hyde Hall team leader Christine Woodhouse. 

Head out into the sunshine with your gardening gear to enjoy these jobs that need doing in the garden in August… 

Lawns can look pretty barren at this time of year, especially if there are long periods of   intense sun and no rain. With hosepipe bans in place in some areas, it’s best to be as sustainable as possible and put the lawn lower down on your jobs to do in the garden priority list. 

“Brown lawns at the end of a hot dry summer may look sad, but will always recover in the autumn,” says Woodhouse. “If you do want to have a green lawn, we advise evening watering, when less transpiration occurs and the ground remains moist for longer.”   

Another valuable tip, advises Woodhouse, is to “allow longer breaks between cuts, and set the mower blades high – the grass will stay greener for longer, with the added bonus of the nectar-rich flowers of Bellis perennis (lawn daisies) and Trifolium repens (clover) being able to grow. Both are a favourite of many bees.”  

If you have a wild– flower lawn, don’t be tempted to cut it too early. “Let the seeds of your grasses and flowers ripen and disperse before you cut and collect the clippings in early August,” says Paul McBride, owner of Sussex Prairie Garden. 

Hedges will be looking unruly by now and will need a tidy up. McBride suggests the end of August is best to avoid disturbing nesting birds. You’ll be rewarded with a pleasing shape and no errant branches.  

“Trim hedges when the new stems start to toughen up (i.e,. once the fresh foliage becomes a similar colour to the old),” says Dan Cooper, the plantsman, presenter and owner of Dan Cooper Garden. “Take care not to cut back into old, bare wood, unless you’ve checked that the plant will regrow successfully. Some shrubs, such as lavender, will suffer or even die if pruned beyond the leafy parts. Most conifers are the same and will never recover. Yew, which has a fantastic ability to regenerate, is an exception.” 

Duncan advises to prune hedges like Prunus laurocerasus or Aucuba japonica with secateurs, not hedge trimmers. “This avoids the cut leaf edges browning off,” he says. 

Check out our best secateurs on test and choose a great pair for the job.

A vital garden job to continue throughout August is snipping fading flower heads. By removing old blooms, you’ll get new ones. 

“Right now, at RHS Hyde Hall, deadheading is important to encourage flowering; a key task also for annuals and perennials that repeat– flower,” says Woodhouse. “You may also find that stray stems need tying back on climbing plants – and not just on roses. Clematis can become unruly, too, and catch out the unsuspecting passer-by with their curious tendrils.” 

Flowers ripe for deadheading in August include roses and dahlias – in fact, you could try these genius tips to make dahlias flower for longer.

“One year’s seeding makes seven years‘ weeding”, so the old gardening adage goes, so keep on top of the weeds. McBride recommends a “weed walk”; taking a turn around the garden with a hoe once a week to keep weeds down.

“Dry, warm weather is the best for making sure the weeds sizzle and die in the summer sun. No need to pick them up – just hoe them out and leave them to dry in the sun, thereby returning the nutrients to your garden.” 

At the allotment or in the veg patch, August is all about reaping what you have sown, with harvesting aplenty (fingers crossed!). Tomatoes, cucumbers and other salad bounty will be ripe, so pick and enjoy. Keep sowing lettuce, radish and spring onions for a succession of salad crops, advises McBride. 

Harvest and tie-in beans like runner and French. At Sussex Prairie Garden, they are experimenting with a bean called the lablab bean, or hyacinth bean. “This climber is ornamental, with purple flowers and purple leaves, and grows in dry conditions, and all parts of the plant are edible, including roots, leaves, pods and beans!” says McBride. 

The leaves of early– planted garlic, onions and shallots are dying down, and can be lifted and dried in a dry shed or greenhouse. Duncan also recommends that lifted potatoes are “stored in crates until the skins are dry enough to bag in hessian.”. 

In the greenhouse, “sow spring cabbage and winter cauliflowers for planting out in autumn,’ says Duncan. 

The main pests in the vegetable patch this month are the cabbage white butterfly caterpillars.  

At RHS Hyde Hall’s impressive kitchen garden, “a daily sweep is carried out in the brassicas to search out the tiny yellow clusters of eggs,” says Duncan. “These are rubbed off by hand.” The garden is organic, so any caterpillars are finished off with Pyrethrum, an insecticide made from a member of the daisy family. The veg garden is also planted with nasturtiums, which attract the caterpillars away from the brassicas. 

Elsewhere, aphids or blackfly can be a nuisance mid-summer. “There is no need to spray chemicals,” says Woodhouse. “Just hose them off with a jet of water. You can also mix up washing-up liquid with water and spray them. That will keep them under control.” 

Generally, established trees and shrubs should look after themselves at this time of year.  

“You can prune for cosmetic reasons, or if you want to raise the crown to be able to walk under,” says McBride. “It used to be thought that newly –planted trees might need water in their first summer after planting, but not thereafter. Due to increasingly hot summers, I would now suggest watering in year two as well.”  

“At this time of year, we don’t advise any planting,” adds Woodhouse. “First, it would be almost impossible to dig a hole, and the plant will be slow to root and simply struggle. Instead, waiting until autumn when there is moisture present is preferable and much easier for both you and your plant.” 

 Looking ahead to autumn, Paul advises the smaller the tree you plant, the better its chances of survival. “They are also cheaper, and I believe that they can catch up and surpass large, expensive trees within three to five years.” 

If your garden is dry, dusty and barren – thanks to the soaring summer temperatures and reduced rainfall, take inspiration from “dry gardens”, such as RHS Hyde Hall, Beth Chatto’s garden in Essex and the Sussex Prairie Garden. All are stunning, impactful and nature-positive gardens that are also drought–tolerant.  

Well-known plantswoman, writer and gardener Sarah Raven agrees: “One of the simplest things you can do is to introduce drought-tolerant plants to keep your garden looking lively and vibrant, without the need for excessive watering.” 

McBride recommends sun-loving plants, such as the delicate Gaura lindheimeri that comes in pink and white varieties, stipa gigantea for interest and light reflection, Amsonia (also known as “Blue Star”), Knautia macedonica for its crimson pincushion heads and the “lovely annual grass Hordeum jubatum, a beautiful ornamental rye grass, which will self-seed around your garden.”