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Bonsai Trouble Shooter

Are you having problems with your bonsai?
If you think your bonsai is sick, compare its symptoms with the list of more common problems above.
Leaves are turning pale yellow and dropping off.
Leaves are mottled with yellow, brown and black spots.
Leaves are green, but crispy.
Leaves are pale green to yellow and new shoots are long and spindly.
Leaves are going black or brown, starting at the tips and slowly working down the leaf.

Mottling of the leaves…
…normally means that you have a pest on your bonsai. Spray with a non-systemic insecticide that kills a broad spectrum of pests , especially Red Spider Mite. Make sure you spray under the foliage and around the trunk. Spray again after ten days and then repeat after a further ten days. Always follow the instructions.

If the leaves remain green…
…but are dry and crispy, then your bonsai has dried out at some stage. This often results in the death of bonsai. To ascertain whether your tree is still alive, make a small cut at the base of the trunk in a couple of places. If there is green just under the bark then it is still alive, if it is brown, then sadly it is dead. If there are still signs of life, then keep it cool and moist until new shoots appear. Be patient as this may take a long time.

Long spindly shoots…
…with pale leaves usually mean that the bonsai is growing in a position where there is not enough light. Move it in to a brighter position avoiding direct sunlight all day. Prune back spindly shoots to the first pair of leaves on that shoot.

Yellow leaves on my Bonsai Tree – What is wrong?

Yellow leaves on a bonsai tree

Yellowing leaves… .

Yellow bonsai tree not always mean that you have a problem. A number of trees, some evergreens included, have leaves which turn yellow at a certain time of the year. Autumn is, of course, when leaves on deciduous trees change colour and fall. Evergreens such as Chinese Elms and Serissas can change colour during and after the winter period. So how do you know if something is wrong?

Is your bonsai deciduous and if so, what time of year is it?

If it is not autumn or your bonsai is evergreen, which of the leaves are changing colour? Old leaves on the inside of the tree, new leaves throughout or both? It is quite common for trees, especially evergreens, to shed old leaves that are tired and replace them with new ones. If, however, all the leaves are turning including the new shoots, then there is a problem.

Please note:
A bonsai is a living work of art and seasonal changes can sometimes be experienced. Please do not be concerned if, within 2-3 weeks of delivery, your bonsai shows signs of yellowing or falling leaves (normally the older leaves and not the new growing tips). Not all bonsai exhibit these symptoms but it is not uncommon especially in Chinese Elms during early spring. Leaf drop is usually quickly followed by a growth period. Within a few weeks you should notice new bright green leaves starting to develop; these are often slightly larger in size but reduce with time and pruning.



The leaves on my bonsai have gone dry and crispy – what should I do?

The leaves on my bonsai have gone crispy

Crispy leaves on your bonsai
If the leaves on your bonsai tree remain green, but are dry and crispy, then your bonsai has either dried out at some stage or it is in such a hot position that water cannot be transferred from the roots to the leaves quickly enough. Dry crispy bonsai leaves
This often results in the death of bonsai.
To ascertain whether your bonsai is still alive, make a small cut on the trunk or branches in a couple of places. If there is a green layer (Cambium layer) just under the bark then it is still alive, if it is brown, then sadly it is dead.
If there are still signs of life, then keep it cool and moist (just damp and not too wet) until new shoots appear. We recommend a bright position but out of direct sunlight. Be patient as this may take a long time.

If you ever notice that your bonsai has become too dry and the leaves have wilted please stand the bonsai in water, so that the water covers the entire pot for 10 minutes. Then return to checking the watering as normal and keep the soil damp. Please do not over-compensate by over-watering. If a bonsai dries out and drops its leaves it will actually need less water because it is not transpiring!

We also recommend misting your bonsai daily with water, this will aid the recovery and help maintain the humidity. It will also speed up the recovery process.


Over-watering Bonsai Tree Symptoms

Overwatering bonsai tree symptoms

Overwatering bonsai treesIf the tips to the leaves on your bonsai go soft and black/brown this can indicate one of two problems:

  • Your bonsai is suffering from over-watering.
  • Your bonsai has been hit by frost or become too cold.

In the case of indoor bonsai, brown/black tips to the leaves is usually indicative of over-watering. Frequently this is also associated with the bonsai becoming loser or wobbly within the pot. Over-watering is not something which happens quickly; it is a slow degenerative issue which slowly rots the roots and the bonsai can even exhibit symptoms of wilty leaves (usually associated with lack of water). This is because the roots become weak and do not function properly.

If you observe these symptoms please place the bonsai in a cooler position with good daylight and out of direct sun. Check the bonsai daily for water and only water the soil when it is barely damp to the touch. It will take along time to see new buds or leaves; in this time you are hoping that your bonsai will re-grow the root system. It is important not to feed a bonsai during recovery.



Spotty Leaves On Your Bonsai Tree

Spotty bonsai tree leaves

Black Spot Spotty leaves on a bonsai

Black spot is a fungal disease which affects the leaves.
On a bonsai this usually shows as small dark coloured spots on the leaves.
It is easy to treat but you will need to spray the foliage with a fungicide (available from garden centres).
It is important to repeat spray according to the instructions on the bottle.
If your bonsai does have black spot you will probably notice spots on all the leaves (new and old). If the spots are only on the old leaves please read on!

Old Leaves

Old leaves (ie not the new growing tips) frequently show small spots. These leaves will drop and new ones will replace them. This is just a sign of aging. If there are no spots on newer/younger foliage them I would suspect that this is the cause.

Red Spider Mite

Red Spider Mite is a very tiny pest, which is just visible with the naked eye but can go un-notiiced. It is the symptoms which normally become apparant in the first instance. Red Spider thrives in warm, dry conditions so rarely affects outdoor bonsai.
Bonsai affected by red spider mite tend to display a pale mottling on the leaves. If you look closely fine silk-like webbing and hanging leaves can also be seen.
Eventually a bonsai with red spider mite will start dropping leaves.
To treat for red spider mite we recommend that you spray twice weekly with plant invigorator. Spray to run off so that the leaves, branches, trunk and under the leaves are dripping. Repeat twice a week for 4 weeks and then return to using weekly.



Bonsai Tree Pests

Pests on a bonsai tree


Aphids (blackfly, greenfly and whitefly) are sap sucking insects which rarely cause a problem for bonsai. Aphids are very easy to identify and easy to treat, so are no cause for alarm. They are more commonly spotted in spring/early summer.
Usually the first sign of aphids is shiny sticky patches on the top surface of the leaves. This is caused by honeydew which is excreted by the insects and drops from the leaves above (see photo 1).
Sometimes black sooty mould grows on the honeydew (see photo 2).
White skin casts can sometimes be seen on the top of the leaves (they can look like a strange insects but are just empty aphid skins). (See photo 3).
It is usually possible to see the aphids, they tend to colonise on the shoot tips (see photo 4).

We recommend that you spray weekly with a Plant Invigorator to prevent pests such as aphids developing.

Should you find that your do have aphid on your bonsai, please do not worry, simply purchase an insecticide from your local garden centre and follow the instructions. If you do not want to spray you can simply pick the insects off the shoots (keep checking that more do not hatch).

Aphid on bonsai tree 1 Aphid on bonsai tree 2 Aphid on bonsai tree 3 Aphid on bonsai tree 4

Scarid Flies…

Scarid flies are not uncommon on seedlings and house plants. They are grey/brown flies which live in the soil surface and do no harm at all. Keeping the soil surface barely damp (and not wet) will discourage them. If you find them annoying simply spray with an insecticide. Occasionally you may spot a larvae, it is small, long white and slender. These flies are not something to be concerned about; they are rarely noticeable after a few days.

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