August is the last month for safely planting deciduous trees and shrubs that are sold “bare-rooted” (other than those already growing in containers). It is also the last opportunity for doing last-minute pruning, dividing perennials, generally maintaining spring flowers, and planting some worthwhile additions to the vegetable garden.
Do not delay planting summer stone fruits, apples, pears, grape-vines, roses, and other deciduous trees or shrubs. Soon, with the approach of warmer nights, these will be bursting into spring growth, and then only those that have been pre-planted in containers by nurseries can be safely replanted.
For success with these deciduous plants, it is most important to make sure that the root is not allowed to dry out at any stage before or during planting. It also helps new roots to develop if a liberal mulch of fibrous compost, dead grass, or leafmould is spread above the root area, if possible before the soil is soaked at the completion of planting. Do not add fertilizer until spring growth is well underway.
Rose pruning should be completed in all but very cold districts as should the pruning of summer flowering shrubs like Lasiandra (Tibouchina), crepe myrtles, if you prefer them kept in shrub rather than tree form, deciduous hibiscus, hydrangeas that are unpruned and the autumn-flowering cassias.
Deciduous fruit trees are also pruned in winter but those grown for their late winter or spring flowers are left until immediately after flowering.
Camellias that are well established also benefit from a light pruning. Those that have reached the rather twiggy and woody stage will benefit from harder cutting. This consists of removing all the thin, twiggy growth close to the major branches, then shortening all other branches back to where the stems are at least lead pencil thickness.
To avoid immediate loss of flowers and temporary denuding of the tree, some gardeners like to treat alternate major branches this way and leave pruning the remainder until the following season. Camellias will benefit from a gentle feeding now. At this time of year when blooms are still present, one of the water-soluble plant foods soaked around the tree will be sufficient. Feed again with this or a camellia food as soon as the new growth appears.
Do not be tempted to feed azaleas now, even though they may be loaded with flower buds. Feeding may prematurely induce new growth shoots that mask the flowers and spoil the spring display. This applies also to rhododendrons.
Occasionally check azaleas that are already flowering for petal blight which, if not controlled, can ruin or prematurely end their display. The first symptoms are brownish or transparent flecks on the petals followed by a premature shriveling of the flower which remains fused to the plant.
There are preparations such as Bayleton which give good results if sprayed every 10 days from the time the azalea buds are showing color.
Don’t confuse this problem with the mottling and grey-bronze condition sometimes found on the foliage of azaleas. This is caused by the lace bug, which is usually dormant at this time of the year, so do not bother spraying for this until signs of mottling appear on the new growth in mid-spring.
Lemons are improved by progressive pruning – that is, pruning the fruit-carrying branches back to a promising new shoot a little nearer to the main branches. Otherwise, the next crop develops from the comparatively twiggy wood of the fruit cluster.
This can be forestalled by cutting and storing the ripened lemons on about half the fruit-carrying stems. (Cut lemons, with a small piece of stem attached, rather than pull them.) To store, place about a 2cm layer of dry sand in a paper-lined carton, place a layer of lemons not quite touching, cover with sand, and continue this way. They will usually keep for a month or two and, surprisingly, their juice content improves.
Check all citrus for woody swellings on last season’s growth. These can vary from marble size to finger length and are caused by the infestation of fall wasp larvae. The only, and compulsory, treatment is to cut these off without delay and burn them as otherwise the adult wasps will soon emerge and reinfect the new spring growth.
In the vegetable garden, potatoes may be planted now in all but the coldest districts. Although they are generally regarded as needing a large area, they still do quite well if the sprouting tubers are set in clumps of four or five with only about 25cm between them. A layer of compost or straw-like material can be spread between the plants as growth progresses to take the place of conventional hilling.
Peas are a good crop to plant now in all districts – the climbing telephone, sugar, snow and snap peas, as well as the dwarfs. Also in all districts, it is time to sow beetroot, cabbage, carrots, cress, herbs, lettuce, spring onions, parsnips, radish, rhubarb, salsify, silverbeet and, in all but warm areas, kohl-rabi and celery.
Chokos may be planted and tomatoes, capsicums, and eggplants may be sown in warm, frost-protected positions. In tropical to semi-tropical districts, the main sowings are beans, tomatoes, cucumber, eggplant, marrows or zucchinis, melons, okra, pumpkins, rosella, squash, sweet corn and cuttings taken from sweet potatoes.
Perennials: All of the suckering herbaceous perennial asters, perennial phlox, and Shasta daisies may be divided and replanted now, particularly if new suckers are already showing above the soil. If foliage is well-formed, as it may be with Shasta daisies, cut back to about half before replanting.
Perennials with woody crowns, including astilbe and Echinops, are also divided now if the clumps are inclined to be crowded. Russell lupins are usually best when replanted every second or third year but peonies are best left undisturbed as long as possible.
Indoor plants in rooms that become chilly at night should still be kept with soil a little on the dry side – watered only when the surface becomes dry about one centimeter down. The exceptions are ferns, potted poinsettias, chrysanthemums, and cyclamens which will appreciate water whenever the surface dries out. Do not feed any house plants until they show signs of new growth, which, in most cases, will not occur until nights lose their chill.
Maidenhair ferns that have reached the tatty foliage stage, maybe cut back to the soil level. Those that are becoming congested with stubs of old-growth may be divided and repotted.
Do not feed until new growth is establishing, then only sparingly.
Annuals: Keep spring annuals well weeded preferably mulched to deter weed growth. As flower buds show color feed with one of the water-soluble plant foods and, to prolong flowering, remove old flower heads.
Watch stocks for aphid attack. These pests usually congregate under the stock foliage, so are difficult to actually see but their presence is indicated by flattened or downward curling rather than upright center foliage. If unchecked the plant becomes deformed and fails to flower properly. Pansies and violas can also be affected by green aphids which cause a mottling and downward crimping of foliage.
In all cases, either spray with pyrethrum or malathion to contact the underside of foliage or, if the latter is too difficult, spray or water foliage with Lebaycid or Kogor, both of which will penetrate foliage to a certain extent. Also, check for rust on Calendulas and English daisies. This shows as rusty-orange pustules on foliage. If this symptom is present, carefully remove and burn the badly infected foliage, then spray once a week with Zineb.
The same treatment can be applied to geraniums which show rust infection, first as pale yellow spots above the foliage with circular formations of brownish dots on the opposite side. In the advanced stages, the rest of the leaf yellows and the once yellow-spotted sections revert to green.