Garden jobs for Summer

General maintenance

  • Weeding: keep weeds down by hoeing the borders. Weeds compete with plants for water and nutrients so try to keep on top of them.
  • Watering: water during the cooler times of the day when there will be less evaporation. Water the compost, not the leaves. If you use a watering can, refill it and leave it outside for next time – some of the chemicals in tap water will dissipate over 24 hours.
  • Feeding: new compost contains nutrients to support plants for 5-6 weeks, thereafter you should use a suitable fertiliser to encourage continued flowering and maintain plant health, especially for plants in containers.
  • Deadheading: most plants will flower for longer if faded flowers are removed. Deadhead roses by cutting back to a bud in a leaf axil lower down the stem. With bedding plants, deadheading stops the plants setting seed, forcing them to produce more flowers. Some plants, such as Petunia and Nemesia, may get straggly and can be cut back hard and fed with a high potash fertiliser to encourage new growth.
  • Camellia and other early spring flowering shrubs set their flowers through the summer. Make sure you water and feed them regularly, especially container grown specimens, for a good show next spring.
  • Remove spent flower spikes on lavender, ahead of cutting the whole plant back when it has finished flowering in the autumn.
  • Cut back straggly and faded perennials to keep borders tidy; feed and water to encourage fresh growth. This will stop tall plants flopping and smothering smaller plants.
  • Ponds: water evaporates very quickly in hot weather so keep a regular eye on ponds and top up water levels if necessary, but only with rainwater. It is harmful for wildlife in the pond to use tap water.

Container gardening

  • You will get to know how often to water large container grown plants, probably 2 or 3 times a week, but smaller containers and baskets need watering once or twice a day in hot temperatures.
  • Feed hanging baskets and window boxes regularly with a high potassium feed to encourage continued flowering.
  • If you still have containers to be planted there are lots of options. Pick ferns and heuchera or possibly anemones for a long lasting display in the shade. Geraniums are a trusty splash of colour in the sun or try an ornamental grass. It’s not too late to plant a container or two of herbs to enjoy in the kitchen, or in your cocktails.

Pruning

  • Summer prune Wisteria by cutting the long wispy shoots back to 5 buds. For guidance on this, look at our Pruning Wisteria notes on our website.
  • Remove unwanted growth from trees. Many trees and shrubs produce a mass of shoots at the base, which need to be removed because they sap energy and strength from the plant.
  • Prune any remaining early summer flowering shrubs such as Philadelphus. Flowered growth should be cut to a strong lower shoot.
  • Remove any shoots with plain leaves on variegated plants such as Euonymus.
  • Trim conifer hedges such as Leylandii to keep under control. Yew hedges and topiary can be cut in August.

Planting

  • If a gap appears in the border, or you find a pot which needs filling, there are plenty of options. Introduce some late summer perennials which will flower into the autumn – Sedums, Japanese anemones, Crocosmia, Penstemon - lots of plants will flower until the first frosts, and many provide attractive seed heads through the winter.
  • Do you have room for a splash of autumn colour? Every garden should have a tree or shrub to provide glorious reds and oranges in the autumn.
  • Make sure you plant well with a big hole, good compost, Rootgrow and fertiliser, soak the plants beforehand and then water in well.
  • Seeds – get ready for autumn sowing of sweet peas and biennials such as foxgloves and wallflowers.
  • Bulbs will be available towards the end of August, ready to get in the ground for a spring show.

Fruit, vegetables and herbs

  • Everything in the vegetable garden or allotment will need attention at some stage, whether supporting tall crops, protecting from slug damage, or harvesting.
  • Continue harvesting summer fruiting raspberries and when finished, cut out fruited canes to ground level and tie in new healthy canes.
  • Prune blackcurrant bushes after harvesting fruit by a third, particularly on the older, darker stems.
  • Keep birds and squirrels off berries with netting.
  • Harvest your fruit trees - cherries, plums, peaches, nectarines and apricots should be ready. Early varieties of apple trees will be ready towards the end of the month.
  • Trained fruit trees (fanned or espaliered) should be pruned and trained now, while the stems are still flexible.
  • Blueberries in containers must be kept watered, ideally with rain water or soft water.
  • Remember to feed lemons and other citrus fruit trees throughout summer with a special citrus fertilizer.
  • Apply a high-potash fertiliser such as tomato food once fruits start to form on tomatoes, peppers, cucumber and aubergines.
  • Water runner beans and tomatoes (and many other crops) regularly. Tomatoes should be kept evenly moist: irregular watering can cause fruit to split.
  • Pick out the side shoots of cordon tomatoes, maintaining one main stem. Remove leaves lower down on the plant to help with air circulation and prevent disease.
  • Check tomatoes for signs of fruit splitting and blossom end rot. Remove damaged fruit and ensure consistent watering to limit further damage.
  • When beans reach the top of their supports, pinch out the leading shoot to encourage more side shoots and beans lower down.
  • Pick herbs regularly to encourage fresh shoots. Most herbs will benefit from being trimmed occasionally with garden shears to encourage a flush of new growth.
  • Sow salad seeds - lettuces, rocket and many mixed leaf seeds can be sown for extended harvesting.

Lawns

  • Continue mowing and adjust the height of the blades when necessary. The general consensus is to raise the blades if the weather is hot, removing less grass.
  • Recently sown or turfed lawns need a good soaking every few days, so that the water gets down to the roots.

Pests and diseases

  • Fungal diseases such as box blight and rose black spot thrive in warm wet weather conditions. Take preventative action - healthier plants are more resistant - and apply appropriate treatments as soon as you see signs of disease.
  • Keep an eye out for the next cycle of box tree caterpillar - there are up to 4 generations a year.
  • Warm weather can encourage pests. Greenfly and black fly can multiply really quickly and it can be difficult to keep on top of them. Build up diversity in the garden by planting a variety of plants to attract beneficial insects such as ladybirds, butterflies, bees and other wildlife, improving the balance of pests and predators.
  • Slug and snail populations continue to thrive. Choose your preferred method of control: wool pellets, crushed whelk shells and Strulch all create a barrier which slugs and snails are reluctant to cross; copper tape around pots delivers a sharp shock; anti-slug bait or pellets should be used thinly.
  • Watch out for powdery mildew on roses and honeysuckle particularly. Remove affected plant debris, water and mulch, and if possible improve air circulation around the plant. If necessary, treat with an appropriate fungicide.

Wildlife

  • Keep supplies of food and water going for the birds. If they are used to finding food in your garden, they will continue to visit. Birds are your ally when it comes to slugs and snails.

Holidays

  • Before you go away…
  • Cut back bedding plants and give them a feed - hopefully they will be full of flower when you return.
  • Group containers together in a shady spot if possible and ask a friend or neighbour to water them. Return the favour when they go away!
  • If somebody is looking after your veg patch, invite them to enjoy tomatoes, beans and other fruit and vegetables, to help ensure that the supply continues when you return.
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