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August 2023


It’s still winter! Cold and windy so be cautious around this time. It has been hinted that we will still potentially have very low temperatures.

General maintenance

Keep an eye on your pots as the wind tends to dry them out very quickly.

Look out for moss development on the bark of the trees. It can cause the bark to rot away. You can control the moss by spaying undiluted grape vinegar on it in the areas where you want to kill it.

Treat deadwood with pure lime sulfur to prevent it from rotting in the cold months. Wait for a warm dry day to treat the deadwood.

Remember Azaleas, Flowering Quince and Coleonema Alba will have spent flowers now. Remember to remove spent flowers. Azaleas can be potted as soon as it is finished flowering.


Beware that Maple branches are very brittle this time of the year and will easily break without warning. A better time to wire maples will be late spring or summer. When defoliating a maple, its normally the best time to also wire them. The branches are then more flexible.


Do not feed newly potted trees. During potting you remove a lot of the roots and the tree cannot absorb the chemicals. The chemicals can also burn and kill the new roots.


Smooth bark Elms are already green and cork bark elms’ buds are also starting to swell. This is the busiest time of the bonsai calendar. It’s time for designing, pruning and potting of most your bonsai.

Start potting your deciduous trees, i. e. Celtis, Elms, Maples, White Stinkwood, Birch, but it’s already becoming late for swamp cypress. Finish potting your swamps before the second week of August. Swamp tends to “bleed” a lot if cut too late in winter. Acacia can be potted from the middle of August. Leave Figs for later in the year.

First plan what you want to do with your tree. If you want to repot it to a new pot then make sure you got the right pot available before potting. Keep a suitable container with water in it ready to dunk the tree after you repotted it, if you use the normal bonsai soil mixtures. If you make use of Akadama, pumice or Leca in your soil mix then do not dunk your tree. These three (Akadama, Pumice and Leca) will float on top of the water if you dunk it.

Finish wiring, pruning, and designing your trees before potting it. Do not do “dramatic” styling work on junipers and pines if you plan to repot them. “Dramatic styling” will place junipers and pines under stress and if you repot it at the same time, it can kill the tree. Rather do the ‘dramatic styling’ one year and repotting the next.

Remember aftercare is the most important part of repotting. You can do the best job in repotting the tree but only one warm day in which your tree is not protected from the heat or wind will kill your tree. A good after care spot will be a cool, protected (wind and sun) area, where the tree will get enough water. The soil must not be too wet, neither must it dry out. I prefer to give a light spray on the foliage of newly repotted trees several times a day for the first three weeks, only watering the soil when necessary, trying to keep a moist environment around the trees. Also make sure that your tree is stable in its pot. If the tree appears to be a bit loose in the pot, while you are potting it, tie it down with wire through the drainage holes of the pot. (Especially if you make use of Akadama, pumice and Leca in your mix) Just remember that you wired the tree into the pot. You will need to remove it later when the tree formed enough roots to support itself. Leaving the wire on for too long can damage the roots, even kill them.

Pests and diseases

In the past few years many different diseases appeared in bonsai collections. We mostly speculate on the types of diseases as well as the desired prevention and cure with different information being obtained from many different international sources.

The best preventative measure for most diseases is a healthy bonsai. Root rot can be prevented with well-drained soil and the correct watering methods. Fungal diseases again thrive in warm humid conditions. A healthy bonsai got the energy and natural resistance to fight these diseases.

Some of these diseases that we found recently are anthracnose, a fungal infection found on several trees but mostly Japanese and Chinese maples. You can recognize the infection from the newly formed leaves will shrivel up and turn black as soon as they start to open. It can look similar to wind damage to young leaves. So far, the best remedy appears to use fungicides. It can be sprayed as a preventative spray on maples. Spray it on the tree as soon as the buds start to swell, a second spray when the buds start to open and again 10 days later. Make use of the indicated dosage on the label. Since Unizeb is not available on the market anymore you can use a copper base fungicide like Viricop. Wooly aphids, thrips and scale can be prevented with Koinor.

Styling and design

It is important to make use of wire on your tree to achieve the best results. Rather spend several hours wiring your tree to get the best result, than saving some time and wire and neglecting the design and progress of the tree. It may sound strange to most to say that it will take hours to wire a tree, but basic medium size maples can take up to four hours to wire properly, wiring every little branch designing the tree. It will be beneficial for the development of your tree to wire the whole tree every 5 to 7 years. In Japan they can take several days to prune and wire a single mature tree.


You can sow your seeds from the end of the end of August.

If you plan to do air layering the best time is from Spring till early summer. Make use of a good quality sphagnum moss when doing air layers.

You can still collect trees like wild olives. Wild Olives that were collected during May are already showing signs of new little buds.

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