Jobs to do in the garden in July

Phew! It’s July. Borders are at their peak, but growth is slowing down so you should have time to put your feet up and take some garden notes. Observe what has and hasn’t worked, plants which need dividing and gaps which need filling. Then, after rousing from your recliner to crack on with the ‘Hampton Court Hack’, reward yourself by compiling a greedy wish list of your must-have plants and seeds for next year.

Hanging Baskets and containers

• In the July heat, hanging baskets and containers can dry out extremely quickly and may even need watering twice a day. Even if it rains, water often barely penetrates due to the thick mass of roots and umbrella of foliage cover so they will need a good soaking by hand.
• The constant watering will flush away nutrients, so it’s important to keep on applying a weekly high-potash feed.
• Keep on deadheading to stimulate new blooms. Pansies and petunias can begin to look straggly at this time of year, so rather than fiddling about trying to deadhead individual flowers shear them back and feed them to promote a flush of new growth and later flowers.

 

Hampton Court Hack

• By early July, some of the perennials which flowered earlier can look a bit tired. It’s time to undertake the ‘Hampton Court Hack’, so called because it coincides with the Hampton Court Flower Show. Try it out on Alchemilla mollis, straggly pansies and violas, astrantias, catmint (Nepeta), and hardy geraniums. Simply shear them right down to the ground, followed by a good soak and you’ll be rewarded with fresh new foliage and possibly a second flush of flowers.
• You can also cut back the all flowered stems of lupins, delphiniums and aquilegias (if you don’t want them to self seed).

 

Bearded iris

• Divide clumps of bearded iris if they are overgrown. Lift clumps and select the largest, healthiest rhizomes for replanting. Cut each fan of leaves to about 15cm (6”), then replant, firming them in well before watering.

 

Box Hedging

• Box tree moth caterpillar is now widespread and can cause severe damage, even death, very quickly. Use pheromone traps to monitor populations – they can have up to 4 generations each season.  Inspect your box for the caterpillar and either pick off the caterpillars or spray with a contact insecticide if necessary. If box caterpillar is becoming a severe problem in your area, it may be wise to consider alternatives such as yew hedging.

 

Prune Flowering Shrubs

• Cut back the flowered growth on shrubs that bloom in early summer including Philadelphus, Weigela and Deutzia. Prune them back to strong young shoots lower down. Also remove up to a fifth of the oldest stems to near the base, rejuvenating your shrub by promoting the growth of new, young shoots.
• After flowering give Helianthemums an all-over trim with a pair of shears, reducing them to neat hummocks which are about 15cm high (6”). This needs to be done every year to promote compact, ground hugging plants which are smothered in flowers.
• With most other Mediterranean shrubs you need to be more cautious – neither Cistus purpureus or Phlomis fruticosa will tolerate much pruning – but to keep them compact you can lightly trim over the soft green shoots without going into the older, hard wood.

 

Watering new plants

Keep watering newly planted trees, shrubs and young plants whilst they are still getting established.

Propagation

• Take cuttings from tender plants such as salvias, and Mediterranean herbs like lavender, rosemary and sage, selecting non-flowering stems from the current season’s growth.
• From now until early autumn, take semi-ripe cuttings from hardy climbers, and evergreen shrubs and hedging plants, selecting growth that has begun to harden at the base.
• Continue to sow biennials, including flowers for cutting such as wallflowers and Lunaria.
• Transplant seedlings of biennials sown earlier in the year and give them a good water. Continue to water them regularly.

 

Summer prune wisteria

• In warm areas of the UK leave this job until August to reduce the amount of regrowth. In cold climates cut back the long whippy shoots now, pruning them back to about five leaves.

 

Greenhouse

• Greenhouse plants are vulnerable to scorch and heat stress, so open all the vents and doors, use shading and damp down regularly.
• Put up yellow sticky cards to monitor pests and keep your eye out for infestations of red spider mite, whitefly, mealy bug and scale insects
• Greenhouse debris can harbour pests and diseases so sweep up any dead leaves and remove dead plants promptly.

 

Roses

• Keep deadheading your roses, cutting back faded flowers to the first leaf behind the flower.
• Pick off any leaves affected by blackspot or rust
• Lightly prune old fashioned, once-flowering shrub roses, ensuring that you don’t spoil their arching habit. Remove any dead, diseased or damaged growth. If there is congested old wood in the centre, remove one or two of these older stems.
• After flowering, prune back any unwanted or congested growth on rambling roses, tying in new replacement shoots. Prune back the remaining side shoots by two thirds.
• Keep an eye out for suckers produced below the grafting point – they are usually lighter in colour with green stems and a different number of leaflets. Rather than cutting them, dig down to expose their origin and pull the suckers off.

 

Lawns

• Help save pollinators and let it grow high in July! Relaxing your mowing regime and setting the blades higher will not only promote stronger growth which is more resilient to drought but will also permit short plants like daisies to flower. See Rewilding the Lawn for more information.
• If it’s hot and dry the lawn may start to look brown but resist the temptation to splurge water on it as it will simply be wasted through evaporation. Trust that underground roots will enable the grass to recover once rainfall arrives.
• Apply your last lawn feed at the beginning of this month. Leave it any later and you will promote soft green growth in the autumn which will be vulnerable to pests and winter cold.

Seed Collecting

• Go around your garden (and perhaps your neighbours!) collecting your favourite seeds from hardy annuals and biennials such as poppies, nigella, and foxgloves. Save the little sachets of silica gel which you find in numerous products and place these in an air tight container with your seeds to keep them dry.

 

Pond

• Ponds can quickly dry up in hot weather so keep it topped up with collected rainwater. If rainwater isn’t available, fill up an empty water butt with tap water and leave it for 24 hours, during which time the chlorine will evaporate.