I am sure not many of you (if any) spent time in July pruning back your figs but that is exactly what I found myself doing at the start of the month. I had noticed sooty mould on some of my figs in June, so sprayed with Confidor, to hopefully eradicate the scale that was the cause of the problem. I realised I would need to carefully inspect, cut back the infested foliage and generally clean them up once the insecticide had done its work, but I was too busy with other things for the next few weeks to do anything further. So cutting back is what I had to do before starting on repotting my deciduous species! I removed many dried out scale insects from what I had left on each tree (very tedious) and sprayed again a week later ‘just to make sure’.
Fortunately my figs are grown under cover (maybe part of the problem?) so should not be damaged by the cold and frosts likely during the last of winter. Once the trees are showing signs of healthy growth in late spring, I plan to remove the last of the damaged foliage. Normally a non-systemic spray such as pest oil is sufficient against scale. It works mechanically by blocking the breathing holes (spiracles) down the sides of the scale insect. My infestation was so bad that some of the insects had formed a protective covering over themselves, which may have reduced the oil’s effectiveness. I will probably spray in spring with pest oil to make sure there is no little scale offspring present to cause the problem again.
Now…on with what to do in August!
The days will start to get a bit warmer during August, although there are surely some cold nights still to come. For this reason any newly trimmed or repotted trees need protection from the weather, particularly if fresh, soft new growth has started to appear. If any of your plants are showing signs of frost damage with burnt foliage, hold back on trimming it off until there is no chance of further frosts. The spoilt foliage, though unsightly, will help to protect the plant from any further damage. Once you remove the damage, the tree will revert to healthy new growth in spring.
Although trees are not drying out quickly at the moment, continue to keep a close eye on your watering. Be wary of those warmer, windy days ahead which will mean you need to check moisture levels daily. Any trees you have repotted during July should be showing signs of recovery and/or new growth. With their recently reduced root mass, it’s particularly important not to let them dry out. Additionally, I normally water them over with Seasol at least once a week to aid their recovery.
If you have not already done so, repotting of deciduous and flowering trees should happen now, as buds are already beginning to swell. Remember too, that trident maples should be potted every year if possible, as they have very vigorous root systems. By the end of August elms and maples, which can shoot early, may need their first pruning back to 1 or 2 sets of leaves. Keep pruning any deciduous trees where any branches extend beyond the perimeter of the desired silhouette.
You can also begin to repot some evergreen trees such as privet, pyracantha, buxus, olive and cotoneaster. Australian natives can be done at this time of year but be careful as some are starting to put on a growth spurt already. July is often a safer time for repotting them.
Whether you are repotting existing bonsai or creating new ones, it’s important to balance what you remove from the roots (percentage wise) with the foliage you remove from the top. You can get away with removing a little more foliage than roots, but the reverse does not work so well. The tree must always have sufficient roots in place to support the foliage on the top with water and also stability. If your trees are a bit unstable in their containers after repotting, it’s a good idea to wire them in place.
August is the best time to repot your pines. Remember that weak branches or those that you want to extend should not be cut back at this time. You can cut back elongated branches and remove unwanted branches on more vigorous parts of the tree to balance any roots you remove during repotting. If you are well ahead with repotting you can also repot junipers, or wait with these until early summer.
August is the best time to do aerial layers on garden stock or bonsai that have grown too tall. If layering flowering plants remove any flowers and buds as the presence of these will weaken the layer. Make sure that any flowering layer does not flower for 12 months from the time the layer is done.
Search out and collect different types of moss to dress your trees, or use decorative pebbles on the soil surface after weeding, repotting or trimming. This will help prepare your trees for our show in September.