July is a time to relax and enjoy the garden – but there are a few things that help to keep displays going and veg plots productive.

Containers, particularly of lush summer flowers such as begonias, fuchsia and petunias, run short of water and nutrients far more quickly than plants in the ground. Stand them on saucers or trays to retain any run-through after watering. In summer they will re-absorb this water. Add slow-release fertiliser to the potting compost to maintain growth and replace the spent flowers removed by deadheading. Some peat-free potting composts shrink as summer progresses. Either top up with a little more or take the plant out of the pot and add more potting compost to the base and sides.

Small pots that cannot hold much water can be moved to the shade or the plants repotted into a bigger pot. Planting them out in the garden is risky in high summer, as it is hard to be sure they are getting enough water.

Young and new plants will need watering, aiming to wet the root zone only. Shallow watering or very deep watering is wasted, as the former is lost by evaporation and the latter sinks below where the roots can access it.

After watering, mulching helps retain moisture and feed the plant and soil biology. Soil life – microbes and worms – are effective in helping new plants thrive. Slugs will be few after so much heat, so mulching won’t encourage them.

Summer flower shows are great places to buy plants. They won’t grow much root if planted in flower into beds and borders. Keep them in their pots in a sheltered shady place, watering to keep them moist and not soggy, and deadheading when necessary. Once the weather turns rainy, they can go out in the garden with much less risk.

Powdery mildew is common in a dry summer. Watering plants helps them to resist infection. Courgettes and cucumbers are especially liable to be infected – remove affected leaves to reduce infections and enhance airflow. Often these prolific crops run out of steam and become unproductive or collapse from mildew in August. In the south, sow some more now for later harvesting.

Adding canes and string is often needed as dahlias (above) and other summer flowers respond to the sunlight, heat and watering with vigorous growth and can flop, breaking stems.

Insect activity is high in July. Some species can cause a problem for plants, such as root flies (Photo: Georgi Mabee/RHS)

Uprooted or hoed-off weeds perish quickly in July and it is well worth suppressing where necessary. Bindweed is very deep-rooted, but it is weakened by hoeing and cutting back, ready to be dug out in autumn. Alternatively, after hoeing, cover weeds, including bindweed and other perennial weeds, with some cardboard held down with compost, wood chips or other mulch. They will be smothered and even eliminated by winter if they can be covered soon.

Insect activity – notably moths and butterflies – is very high in July, which is very welcome, as plentiful insects mean thriving garden wildlife, including birds.

Some insects, though, are less welcome. Root flies of carrots and cabbages peak soon as the second generation of the summer emerges. Keep carrots, celeriac and parsnips protected against carrot fly with fleece or insect-proof mesh to limit boring by maggots.

Cabbage root fly can be thwarted by cardboard collars around each plant as they are set out. Ones planted in May will be safe from root fly now, but cabbage caterpillars are becoming numerous. Picking off is usually enough to prevent serious damage.

Guy Barter is the Royal Horticultural Society’s (RHS) chief horticulturist. The RHS is a charity inspiring everyone to grow via its research, advisory, outreach, shows and gardens. For more information, visit: rhs.org.uk