July is another good month for enjoying the garden rather than for planting owing to the heat. The most important task now through to September is ensuring plants have sufficient water. Except for several native plants and well-established drought-resistant plants, all plants need regular watering.
Water large trees deeply but infrequently to encourage deep roots, but avoid watering almond, olive, carob or fig trees. Allow the soil to dry somewhat between watering as this will allow air to get into the soil and give oxygen to the roots. The best time to water is early in the day.
To help conserve water and to suppress at least some weeds, consider laying down a mulch, but remember that snails may seek shelter in mulch.
Water all bougainvilleas under 3 years old, young drought-resistant plants, citrus and avocado trees, succulents growing in the ground, lawns, roses, vegetables, extra water for north-facing shade plants if the sun hits them, daily for impatiens and nearly all garden plants but for a few truly drought-resistant ones.
Fertilise fuchsias, water lilies, roses, ferns, tropicals, tuberous begonias, impatiens, coleus, June blooming azaleas, cacti and euphorbias in the ground, and vegetables.
Citrus and Avocado Trees
Don’t let these these dry out in July or August as a good deal of fruit may fall off. Established trees need deep watering every two or three weeks depending on soil type and weather. Newly planted trees usually need deep watering once a week.
For citrus it is best to water in a broad band starting one-third of the distance from the trunk to the drip line and finishing an equal distance from the drip line as this is where the feeder roots are. Keep the tree bark dry to prevent fungal disease.
Avocados need water all over the ground under their branches, up to one or two-thirds of a metre from the trunk. Water slowly. Avocados are highly prone to a fungal root rot which is spread by infected plants and thrives in wet and poorly drained soil.
Continue to check for pests and to water, fertilise and prune by picking the flowers. Irrigation can be increased to three times per week. Keep the ground around the plants well mulched.
Most modern climbing roses bloom continuously from April to January and should be pruned with other roses in January. Old fashioned ones which bloom only once a year in spring should be pruned after bloom once they are over three years old. This includes rambler roses (which have small, flat flower clusters no bigger than 4 cm) unless you have chosen to allow the rambler to sprawl over roofs or trees where it will continue to grow and bloom. If this is the case, you may wish to clear as much of the dead interior as possible. Pruning back allows you to control the size of the rambler. Remove the old grey wood and canes which have bloomed, but leave any fresh green canes. New growth will start in summer; cut off any weak new canes at ground level.
Annuals and Perennials
Continue to deadhead and to water well. Cut back spring blooming perennials which have ceased flowering with the onset of summer. Strengthen and shape lavender shrubs by shearing them after bloom.
Hydrangeas – once the flowers have faded, cut back each stalk that has bloomed, leaving only two buds from which new wood will grow to bloom next spring. Young plants should be cut back only lightly. Green stems which have not bloomed will bear flowers next year, or possibly later this year if they are facing north (their happiest position is east facing). Feed for growth.
Hibiscus – Continue to prune, water and fertilise. Wash the plants if whitefly is a problem. Hibiscus can be planted now. The more exotic flowered varieties are often less vigorous and lankier in growth than the more common ones.
Camellias and Azaleas – Feed camellias for the third and last time about four or six weeks after their last feed, but avoid overfeeding. Keep the roots damp but not soggy and ensure that soil is not collecting around the trunk. Give azaleas that bloomed in June their first feed of the year immediately after the blooming ceases; don’t feed again until late September. Check them for signs of chlorosis (an iron deficiency which is manifest in yellow leaves) and give them iron chelate if necessary. Propagate camellias and azaleas by layering.
Succulents and Cacti
You can plant succulents all year. Most like full sun but some need partial shade where most container grown specimens do best. Those which bloom usually do so in winter or spring. After succulents and cacti have finished flowering, cut off the spent blooms and seedpods if they are unsightly. Clean up all succulents by pruning off any diseased or dried bits.
Feed all cacti and euphorbias in July with a proprietary fertiliser. For succulents in containers feed them once a month during the growing season. Many succulents, other that cacti and euphorbias, need little or no fertiliser when grown in the ground.
Throughout the year, succulents in containers need water only during dry spells. If the soil 2 cm below the surface is dry, then it is time to water. But in July most container grown succulents will need water, usually every one to three weeks throughout the summer and autumn as will succulents growing in the ground every two or three weeks. The exception is lithops (‘living rocks’) which should be watered from March 1st to July 1st and then left without water in July and August. Resume watering in on September 1st and continue until they finish blooming in mid-November. Put them under cover in the winter so they get no rain and allow them to go dry through the winter.
Cut cool-season grass such as perennial ryegrass and fescue about 4 cm high and not less. Most cool season grass need shallower and more frequent watering than warm season grass; in hot weather watering should be twice or three times a week. Any time between midnight and dawn is the best time. Don’t fertilise cool season grass.
Warm season lawns such as Bermuda, zoysia, and kikuyu are growing at their fastest now. Cut it short to keep it in bounds. Water deeply and infrequently; some can go as long as two weeks between depending on the weather, although sandy soils will require more frequent water. Fertilise every four to six weeks during the growing season for most but avoid feeding kikuyu unless it is not growing well.
As vegetables are harvested, keep the rows cleaned up. The most important job in July is to provide a steady supply of water. Continue to apply fertiliser halfway through the vegetables’ growing season. Monitor for pests.
Summer vegetables can still be planted, but their growing season will be much shorter and they won’t fruit until the autumn. Corn, cucumber, aubergines, squash, and tomatoes can be planted as well as beet, carrots and radishes but real success depends on sufficient hot weather to ripen them in October.