Seasonal Notes for Summer

Bonsai maintenance over Summer, watering, fertilising and wiring jobs for December and January.



This is perhaps the most important aspect of our summer work, if we neglect to water our trees the results could be fatal. Also remember my saying: “if the tree is dry, water it; if you’re not sure, water it anyway.”

On very hot days it may be necessary to water both in the morning and in the evening. It is a good idea to move cool climate deciduous trees such as Maples and other sensitive deciduous trees out of the full sun and into semi-shaded area.

I recommend watering the foliage as well as root soil area. Foliage watering reduces the dust that could accumulate on the leaves.

If you have a lot of small trees, you could place these trees into a large tray Cilled with sand, so the bonsai is surrounded by the sand. The sand can act as a water absorber and protect from any accelerated drying out.

Remember, it is impossible to overwater your trees in summer. Any signs of wilting or death, usually is related to drying out or insect damage. In summer it is one or the other. Ensure the watering is completely saturating your tree. Misting only the foliage with a sprayer is totally inadequate.

If you’re going on holidays, it is an idea to show the person who is looking after your trees how much water to give and how you would like to do the watering. Also show them how to tell when it is enough. Most people are unaware of how much water a bonsai needs.

Also ensure:

Another option if you have a collection is to think seriously about installing an irrigation system.

I highly recommend this option for peace of mind. But I would recommend following up with watering as the drippers only water one section so don’t be afraid to move the sprinkler head around every week or two.


 Maintain fertilising until mid-January and then halt until mid-February as the hot weather will have forced the plants to reduce their growth rate. Continue to use your soil conditioners such as Seasol.

Water all your trees well before fertilising, to protect the delicate feeding roots from fertiliser burn. Never fertilise a dry plant and avoid fertilising on very hot day. Always read the back of the label before using.


Remove all your wire in December to give the plants a rest. Start to re-wire again at the beginning of March when the weather cools and the plants are still very flexible. Do not let the wire cut into the bark. Avoid heavy bending. The branches are full of water and bending will cause branches to snap like celery or crack at the ends.