While the weather remains warm, it’s a good time to repot many species, particularly evergreens like pyracantha, cotoneasters, olives, star jasmine etc. Recently repotted trees will need protection if the nights suddenly become cold within the first couple of weeks after repotting.
It is a good idea to tidy up conifers as well. Remove any dead or overly dense foliage on junipers and reduce the needles on species such as pines or cedars by removing any that are on the undersides of branches, where you don’t want future growth. Remove unwanted candles on pines, leaving no more than two at any junction.
It’s now too late to prune back figs and they should be left until the warmer spring weather returns later in the year. While the weather is still warm, maximise the amount of sunlight they receive, but when the nights become cold move your figs to a more sheltered spot. Tropical species like figs and bougainvillea can be severely damaged (even killed) by frosts during winter.
Keep fertilising to build up the strength of your trees to handle the chilly months ahead. Use a low nitrogen food to prevent a rush of soft new growth as this may be damaged by colder nights. It is particularly important to feed deciduous species during autumn (while the leaves are still green) to maintain their health over the winter dormancy and prevent problems such as die back.
There are three main nutrients in most fertilisers. The balance of these is known as the NPK of the product. Nitrogen (N) produces vegetative or top growth, phosphorous (P) produces flower buds, fruit and root development and potassium (K) builds strong healthy plants. While the weather is still warm (late summer and autumn) flowering trees are setting their buds for spring and a food higher in phosphorous is appropriate during this period. Remember that many Australian native species are sensitive to phosphorus, so you should only use a fertilizer with 3% or less of this nutrient on them.
Sunny days and cool, dry nights will hopefully enable maples, liquidambars, ginkgo, prunus varieties etc to show a lovely display of autumn colour before the leaves fall.
Autumn is a good time to do any wiring on trees, as the tree’s growth is generally slower over autumn/winter and the wire can be safely left in place longer. Wiring done in spring, on the other hand, needs to be constantly checked or unsightly cutting in can happen alarmingly quickly.
Watering can most likely be reduced at this time, as the heat of the sun has eased off somewhat, but be alert, particularly if it suddenly becomes windy. It’s still important not to allow your trees to dry out.
Last but not least, keep up with the weeding! Remember it’s your trees you want to nurture, not the weeds. I have a veritable carpet of tiny weeds in some of my pots, thanks to the recent rains and the unkempt yard next door!