Seasonal notes from Alex
Early Autumn
During the months of April and May the weather is getting cooler and the days are noticeably shorter. The deciduous trees are changing to their autumn colour.
No doubt you are all pondering this as you look at your bonsai and say what should I do next.
Re-potting
I would advise that if you haven't done your figs and natives you should be doing them now or wait till August. Pines, in particular, White pines and other more root sensitive trees in relation to Sydney heat are fine to re-pot from now.
Deciduous / flowering trees are able to be re-potted. In essence, if it is a northern hemisphere tree now is the time to re-pot your tree.
Autumn is my favourite time to repot. The reason is the length of time the season offers. Warmish weather and cooler nights whilst the soil is still warm.
 As opposed to Spring where from November it can be too hot for some trees It is quite short time in Sydney and where certain root sensitive trees go into shock too easily, in particular, trees that have already bloomed from re-potting.
Your tree needs re-potting if it shows these signs:
- Dries out too quickly and starts to wilt;
- Drains slowly and stays wet for a long period of time;
- Isn't responding to any fertilisers you give;
- Has suffered some water related stress in particular during summer; premature shedding of foliage or unexplained yellowing of foliage.
- And the more unusual; the tree did not like to pot.
These signs are related to the fact that the soil has been exhausted or the tree is root bound or has poor root growth.
Watering
Watering is without doubt a complex issue with so many variables. First and foremost use your common sense. The more cool weather does mean it requires less frequent watering however the quality of watering should never waver. That means you should still water the tree until water drips from the bottom of the pot. Try to not let the tree dry out but do not let the tree dry out completely.
I may recommend watering the tree every two to three days depending on the relative toughness of the tree. Do not let the tree go an entire week without water. That is unless the weather has turned exceptionally cold.
If you do find that you are uncertain, water the tree anyway. Keep in mind while root rot is always a possible risk and the signs are similar to dry out when viewing the foliage. It is not something that happens frequently. Simply put the factors that would keep the trees soil constantly wet would have to include:
- Very little sunlight to no direct sun.
- A position that is poorly ventilated.
Wiring
For those who are interested in wiring now is the best time of year to be wiring. I would advise against any real heavy bending. This technique is more for mid-winter. It would be ideal to remove any wire on your trees that was attached last year.
Try to cut the coils as opposed to unwiring by hand. As it may break branches unnecessarily or bump off very important buds.
Fertilising
At this of year use a mixture of seaweed extract such Seasol or its equivalent and a high potassium fertilizer such as Manutec Bloom Booster or Richlea Better Bloom.
I also found if your tree is lagging in health Nitrosol, Amino gro, and other nitrogen balanced fertilisers are great to bring growth too.
My advice is use discretion depending on your overall trees need. I would recommend fertilizing at half strength every 2 to 3 weeks or once a month at full strength until the leaves drop off your maple trees. (That is usually my sign to stop fertilising)
Your ratio should be at half strength and that is regardless of the size of your watering can.
We use this type of fertilizer because it will stimulate them after the long summer; causes a thickening of the trunk and stores food for the tree come spring.