July is often one of the hottest month of the year and a great time to sit out and enjoy your garden. Keep plants looking good by regularly dead-heading, and you’ll enjoy a longer display of blooms. Make sure you keep new plants well watered and hoe off weeds, which thrive in the sunshine.
Sowing and planting:
Plant autumn-flowering bulbs such as autumn crocuses, Colchicum, Sternbergia, Amaryllis and Nerine, can be planted now.
Continue planting perennials. These delightful plants give excellent value for money, flowering year after year and can also be divided to make more plants as they grow.
Deadhead flower borders regularly to prolong flowering. Disbud and dead-head dahlias if growing for large blooms. Leave roses that produce attractive hips.
Cut back delphiniums and geraniums after the first flush of flowers to encourage a second flowering period. Feed after cutting them back.
Cutting back, pruning and dividing:
Help revive tired displays in baskets, pots and tubs by cutting back plants and feeding to encourage new growth. (Click here to visit our fertilisers page.)
Cut back and feed delphiniums and geraniums after the first flush of flowers to encourage a second flowering period.
Deadhead flower borders regularly to prolong flowering.
Plants with a carpet-like growth habit, e.g. some alpines, can become patchy, with central areas dying off. These patches can be in-filled with gritty compost, to encourage re-growth.
Take cuttings of patio and container plants ready for next year.
Pinks and carnations that have become leggy, can be propagated by layering or by cuttings. Propagation can improve the appearance of untidy clumps.
Take semi-ripe cuttings of shrubs such as Choisya, Hydrangea (see picture below) and Philadelphus. Root them in pots of gritty compost in a cold frame or even with a plastic bag tied over them.
Clematis can be propagated by taking internodal cuttings (i.e. taking stem sections above and below a leaf, rather than cutting the stem immediately below a leaf joint).
Pruning and training:
Tie-in climbers and ramblers as they grow.
Fast-growing hedges such as Leyland cypress should be clipped as necessary throughout the growing season.
Prune June-flowering shrubs such as Philadelphus and Weigela after flowering. Prune deciduous magnolias if necessary.
Prop up tall perennials such as lupins, delphiniums and gladioli if staking was neglected earlier in the season.
Liquid feed containerised plants and keep well watered in dry spells. Click here to visit our fertilisers page.
Some late-flowering border perennials may benefit from a quick-acting feed before they come into bloom, especially if the soil is not very fertile.
Mulching borders can help retain moisture, and keep down the weeds – this will save a lot of work. A really thick layer of mulch (5-7.5cm/2-3in all over) works best.
Most perennial weeds are best dealt with in the summer when the weeds are in active growth. Digging out often works, but applying a weedkiller can be more practical, particularly for large areas.
Water all ericaceous (lime-hating) shrubs, including camellias and rhododendrons, with a generous helping fertiliser specially formulated for acid lovers. (Click here for details on our fertilisers page.)
Ensure newly planted trees and shrubs do not dry out. They often need much more water than people imagine.
Remove rose suckers and tree suckers.
Sow seeds outdoors of of spring cabbage, turnips, Oriental vegetables, chicory, fennel, and autumn/winter salads. Carrots can still be sown, but beware of carrot fly when thinning existing seedlings.
Ensure all vegetables get a regular, consistent supply of water. This will aid healthy development, and help to avoid diseases, disorders and bolting.
Cover brassicas with fine netting to prevent cabbage white butterflies laying their eggs on the leaves.
Pest and disease watch:
Watch out for aphids (greeenfly and blackfly) on stems and leaves of young shoots.
Vine weevils can also be a problem at this time of year.
Sudden collapse of apparently healthy clematis, especially the large-flowered cultivars, could indicate clematis wilt.
In dry weather powdery mildew can play havoc with plants such as clematis, roses and Lonicera.
Look out for and treat black spot on roses and scab on Pyracantha.
Inspect lilies for the scarlet lily beetle (pictured below) whose larvae can strip plants in days.
You may notice damage to leaves of Viburnum by viburnum beetles. The damage is not usually bad enough to warrant treatment.
Neat circular areas removed from the edges of rose and other leaves are telltale signs of leaf-cutter bees at work. These fascinating creatures are best tolerated since damage is rarely severe.
In the greenhouse:
Damp down greenhouses on hot days. Ventilation and shading is also vital.
Cuttings can be taken and grown on in the greenhouse. Fuschias and pelargoniums are good candidates.
Carry on pricking out any seedlings sown earlier in the season, when they are large enough to handle. Other young plants, already pricked out, may be ready for transplanting to larger pots.
Many greenhouse pests will be active during the summer months. Check plants regularly for signs of glasshouse whitefly, leafhopper, glasshouse red spider mite, mealybugs and scale insects. Ensuring that greenhouse plants are kept in appropriate cultural conditions will help them resist attacks by pests and diseases.
Keep mowing regularly, except during drought. In hot weather, set the mower at a slightly higher level than normal for early summer. This can prevent the lawn drying in hot weather.
Last time to apply a liquid summer lawn fertiliser, especially if a spring feed was not given. A soluble feed and weed product may be useful if there are weeds present in the lawn.
Don’t worry unduly about brown patches on the lawn – they will recover quickly when the autumn rains arrive.
New areas of grass, sown or turfed in the spring will need extra watering to keep them going through their first summer.
Lawn growth slows down in late summer. Raise the cutting height slightly as the month progresses, to help the grass better resist the wear it suffers in summer.