The last few months have been very hot and there’s more of the same ahead, so it’s still important not to let your trees dry out. Some shallow or smaller pots rmay require watering more than once a day at this time of year and should be kept in a more sheltered position for protection from drying winds and the hot sun.
Pots prone to drying out can be placed on trays with pebbles or on something such as clean polystyrene meat/fruit trays to maintain humidity around them. Plants such as wisterias, swamp cyprus, lilypillies, melaleucas and banksias should also be sitting on pebbles in trays of shallow water, as they are very thirsty species. Keep your maples and other deciduous species sheltered from hot, dry winds and preferably under shade to prevent burning of their leaves.
Watering is best done in the morning, as early as possible. When watering on hot, windy days mist all foliage and surrounding area of trees to create a humid environment. Immersing pots in water once a week can also help keep plants in good condition. Adding a seaweed solution such a Seasol to the tub when you do so can give an added boost to stressed trees.
Continue to fertilise all your trees through the latter part of summer but don’t do it on very hot days to avoid burning the roots. Any deciduous trees which have been defoliated earlier in the summer should have been placed in a shaded area until next month and then only exposed to sun when the temperature is not too high. The new sets of leaves will be smaller, and colour better in autumn, because they will have a higher concentration of sugars.
By now you should have defoliated any figs in your collection and have a good flush of new and smaller leaves. There is still time to repot figs if you haven’t got to them yet but once the nights start to cool later in the month it will be too late.
Black pine branches which have matured since forming in the spring may be cut back by half to encourage more compact budding. Do not cut back where there are no needles.
Should we get rain and the resulting high humidity, watch for any powdery mildew appearing on crepe myrtles and oaks; treat appropriately. Eco fungicide, for example, is quite effective and safe, but needs to be re-applied every 7-10 days.
Many species of trees have two growth patterns in a year- spring growth which gives new leaves and lengthens branches and the second spurt of autumn growth thickens the trunk. This latter spurt is the most important for bonsai grower, as it improves the appearance of age in our trees. This is why using an organic fertiliser in the final months of summer and early autumn is important.
Continue to shape branches throughout late summer, with the exception of any sacrifice branches which should be left to grow unchecked. Rotate your trees so all sides get an equal amount of light for even growth distribution.