How to revive a dying bonsai tree

Just as in medicine, effective bonsai treatment is impossible without a correct diagnosis. Perhaps after reading this article you will be able to determine the cause of your pet’s illness on your own, but it is also possible that, left alone with the problem, you may feel unsure of your own strength. In this case, seeking help from more experienced professionals may be appropriate. Your appeal should be as informative as possible and be accompanied by high-quality photos of the tree.

We are losing it!

Most often the problem of the need for urgent resuscitation is faced by those to whom it was presented as an original gift. It is not always possible for the new owner to have enough time and care for the new pet. Sometimes, moreover, he does not even know the species of tree, not to mention the nuances of maintenance. The experience shows, that even the general recommendations of the seller to water the bonsai three times a week, to keep it in a light window and to nourish it regularly, can lead to disastrous consequences. With the wrong substrate this watering regime can lead to flooding, heavy feeding can lead to chemical burns, and keeping on a bright but cold window sill in winter can lead to rotting of the roots. When fatal consequences are discovered, he usually no longer has time to study the literature on plant physiology or read dozens of pages of specialized online forums. It is necessary to act, and act without delay!

Determining the cause of the disease

The first thing you should do is to take a pencil and remember and describe in as much detail as possible everything that has happened to the bonsai over the past month or two. Treat this as responsibly as possible, as even a seemingly insignificant fact can help in making a correct diagnosis. A “medical history” of your bonsai might look something like this:

  1. Species of the tree;
  2. The period of time the tree has been in my possession;
  3. Where was it purchased or where did it come from (bought in a store or dug up in nature)?
  4. The volume of the pots in liters;
  5. Presence of drainage (if known);
  6. No signs of recent transplanting (signs of recent transplanting – the relative looseness of the substrate, the ability to distinguish its components, the tree is not firmly seated in the substrate);
  7. Substrate composition and quality;
  8. Frequency and method of watering (including how water is absorbed when watering, whether it leaks from drainage holes, temperature of water for watering);
  9. Current location of the bonsai, has it changed recently?
  10. Lighting: lighting (yes/no), which side of the window, etc.
  11. Presence or absence of draughts;
  12. Has there been any pruning? If yes, how long ago and how severe?
  13. Feeding;
  14. Has the tree been left in the care of someone else?
  15. What is the manifestation of the disease?
  16. Are there signs of insect activity (spider webs, etc.)?
  17. How long ago were the first symptoms detected?
  18. Has the tree stopped growing or is it still growing (new leaves appearing)?

Remember any little thing. Sometimes your loved ones may not want to upset you by telling you that the pot was accidentally knocked over by them or pets.

Knowing the species identity of the tree is very important. Often, the change in color and the falling of leaves in medium-sized trees in October and November is perceived as a fatal manifestation of some disease, whereas it is natural for them to leaf out. Very often the cause of the ailment is digging up young trees in nature in order to keep them at home. Many people don’t realize that such trees need a natural resting period of a few months at a lower temperature (+1 to +6) to function properly, which not everyone is able to provide in home conditions. Instead of reanimating such trees, it is better to return them to their habitat, and for the apartment choose a more acceptable species.

Despite the fact that evergreen species of trees do not shed their leaves or needles completely at the end of the growing season, the life span of individual leaves or needles is not infinite. A small portion of them may turn yellow and fall off, and this is a normal process. This is often encountered by ficus owners.

If you were not able to independently determine the cause of the disease of bonsai and decided to seek help from one of the Internet forums, it is necessary to accompany your appeal with the “history of the disease” discussed above and accompany it with high-quality photos of the general appearance of the tree in the pot and a fragment illustrating the manifestation of the disease.

Making a diagnosis

All possible causes of tree disease can be roughly divided into several main groups:

  • consequences of desiccation;
  • consequences of overwatering (flooding);
  • freezing;
  • chemical burns;
  • fungal diseases;
  • exposure to pests.

Determination of the true cause is important for the correct choice of a set of resuscitation procedures. Diagnosis of plant diseases and pests is devoted to more than a dozen serious thick books, so it is not possible to give complete and exhaustive information in one article. At the same time, sometimes it is enough to assign the cause of the disease to one of the above groups in order to choose the right course of treatment.


The consequences of desiccation are desiccation of young, not woody shoots and foliage (sometimes without a significant change in its color). The tree becomes mummified. The remaining leaf laminae lose their turgor, thinning, sometimes a little twisted. In conifers, the needles turn pale, lose their flexibility and become brittle. If the tips of young shoots or needles break when you try to bend them with your fingers, the tree is already dead. If the twigs bend and green cambium is visible when scraping off the bark, there is a chance for recovery. For resuscitation in this case it is necessary to:

  1. Remove the tree from heating sources or from direct sunlight in conditions of scattered light, but still sufficient light.
  2. Make up for the water deficit by spraying the crown from a sprayer and covering it with a transparent plastic bag. The ideal would be to put the tree for a few days in a greenhouse with increased humidity in the air.
  3. The first watering of the soil after desiccation should be sparing. Many people make the fatal mistake of immediately immersing the pot with parched substrate in a large container of water. If the soil in which the tree grows is moisture-intensive and not structured enough, such a procedure will displace all the air from the soil pores and the drying will be added to the hypoxia (lack of air) of the roots, which will not allow them to function effectively and fill the water shortage in a short time.
  4. In the future, you need frequent spraying of the crown, including a solution of stimulant and adaptogen “EPIN-Extra” according to the instructions. Every six hours for a quarter of an hour it is necessary to remove the bag from the crown to ensure its ventilation. As a rule, the consequence of proper rehabilitation procedures is an increase in leaf turgor, increased watering of shoots, and further growth.

Overwatering (flooding)

Overwatering or flooding of the soil is probably the most common cause of disease and death in inexperienced bonsai owners. For full growth and development of a tree there must be a sufficient amount of air in the soil. Roots, as well as leaves, flowers and shoots participate in the process of breathing, absorbing oxygen and releasing carbon dioxide. When flooded, water displaces air from the soil pores, preventing this process. If the soil is relatively light, sufficiently structured and airtight, a single flooding does not harm the tree, because, firstly, the excess water through soil capillaries drains through drainage holes into the pallet, and secondly, a healthy plant with a strong and branched root system, like a pump, begins to absorb moisture from the soil and by transpiration release it into the air through the crown. Prolonged stagnation of water in the pot with a lack of air can cause rotting of the root system. Particular care must be taken when transplanting the tree. Often wishing to have a bonsai at home or in a garden in a container dig up a miniature tree growing in nature, put the clump of earth in the first pot that came to hand (or even brought from the forest in a bag) and in the same soil in which it grew in natural conditions. Transportation compacts the soil, disrupting its capillary structure, which could help excess water to drain away. The amount of available air in the soil is reduced many times over. The root system, damaged during digging, can not fully function and extract moisture from the soil with the same intensity. If you continue to grow the tree in this form, you are sure to encounter root rotting. Characteristic signs of flooding are a decrease in leaf turgor, drooping tips of young shoots. The ends of the leaf blades turn brown.

Another common cause of root rot is watering with cold water or placing the bonsai pot on a cold window sill. A decrease in soil temperature significantly reduces root system activity, which can lead to moisture stagnation and the negative effects of flooding.

The first and most important thing to do to resuscitate is to eliminate the cause of the adverse effects, namely to transplant the tree for a short period of time into a light, air-intensive, preferably mineral substrate. You can use pure acadama of coarse fraction, pure zeolite (such as cat litter “Barsik Effect”), crushed volcanic lava, vermiculite, perlite. In the latter cases, you need to fix the tree in the pot with stretchers, because vermiculite and perlite are very light substrates, and do not provide a reliable stability of the plant. When transplanting, the old soil must be removed carefully, if possible, with as little trauma to the small roots as possible. It is better to do this procedure with your fingers, kneading and shaking off the excess soil. After cleaning the roots, it is necessary to carefully inspect them. The presence of rotten roots that easily break off at the slightest effort is another confirmation of the diagnosis. These roots should be cut with sharp scissors or secateurs to healthy areas. Preferably, before planting in a new substrate, place the root system for two to three minutes in a solution of some root formation stimulant, such as Zircon. The same solution can be used for subsequent watering. It is worth noting that the pot in which the tree will be the whole period of reanimation, should have drainage plants in diameter and in sufficient quantity to effectively remove excess water from the substrate. During the resuscitation phase, you can forget about aesthetics for a while, up to using a plastic colander as a container. It is important to remember that the mineral substrate is not moisture-absorbing enough and dries out quickly, so watering must be done much more frequently than usual.

It usually takes three to six weeks for the root system to recover and depends on the type of tree. The appearance of young green leaves in the crown means that the roots have recovered and in a week or two your pet should be transplanted to a substrate more suitable for permanent bonsai placement. When transplanting, the dried mineral substrate in which the plant was resuscitated easily crumbles from the roots. This allows you to move the root ball without damaging even the small endings.


Freezing occurs most often when plants are transported or moved during cold weather. Some plants only need to spend a few minutes outside or in the cold van of a car to experience stress. A major sign of frost is the sudden loss of most of the foliage, and this can occur without a change in coloration. Because the soil in the pot has greater temperature inertia, the problem most often only affects the above-ground part.

If the tree is healthy, when placed in proper conditions, the bonsai will usually recover without problems without assistance. But if the pet is weakened, or the new conditions are not at the required minimum, without your intervention, the consequences can be fatal. In this case, after losing much of its green mass, some of the roots that nourished it will die after a while.

As an intensive therapy in this case, a “sweat lodge” (analogous to a sweat lodge in a bathhouse) can help. Put a wide basin in the bathroom, at the bottom of it put a shower head, on top of the basin set the grid or two wooden slats. On these slats set the pot with bonsai. Now this whole structure from above is covered with a large bag and let a stream of hot water through the shower. It is desirable to cover the tree with a bag of such size that it covers not only the tree, but also the pool. In this case, the water vapor will come out not outside, but inside the bag. This is best done in the evening. The hot water should circulate for 20-30 minutes, after which the water flow should be shut off and the tree should be left in this form under the bag until morning. Note, after losing a large part of the leaves the tree will need less moisture, so watering should be reduced for the reanimation period and in no case water the tree before the “steaming”. “Steaming” should be repeated four to five times. The first two times are two nights in a row, and subsequent ones should be repeated every other day. In the morning, the tree should be placed in the usual light place. In addition to the above procedure, the crown should be sprayed with a solution of stimulant according to the instructions.

Chemical burns

Damage in the form of chemical burn is much rarer, mainly due to over-fertilization or improper dosage of mineral fertilizer solutions. A striking feature of this lesion is the unnatural deformation and twisting of the leaves without changing their color. The reanimation procedures are the same as those for frost damage. If you find that you have significantly exceeded the allowable concentration of the mineral fertilizer solution within a few hours after watering, you need to sprinkle the substrate in the pot several times with clean water at room temperature.

Fungal diseases

Fungal diseases are very diverse and complex in terms of both diagnosis and treatment. Fungi that have infested the tree have a sporulation cycle of one year, so treatment takes a year or more. If the tree is very weak or of no value to you, it may make sense to destroy the diseased plant to prevent the disease from spreading.

In the first stage, fungal diseases show up as various kinds of leaf and needle spots. In the latter stages – the appearance of fruiting bodies on the trunk and skeletal branches. If the corresponding diagnosis is confirmed, it is necessary to isolate the damaged plant from the rest immediately. As reanimation procedures, multiple treatment of the tree with fungicides (preferably systemic action) in accordance with the instructions, and for non-mycorrhizal tree species, replanting with complete replacement of the soil mixture is prescribed. If removal of diseased leaves and needles will not cause significant damage to the tree, they should be removed and burned. When treating the crown of mycorrhizal trees, the substrate surface should be covered with a film to prevent the solution from getting into the pot. During the whole period of treatment, the sick tree should be well nourished. Its living conditions should involve good light and proper watering. Preventive treatment with fungicides should pass all other plants that were together with the affected one. If the fruiting bodies of fungi appear on the branches, the latter are cut out with sterile tools and burned. The cut surface is treated with a fungicide solution and caulked. The appearance of fruiting bodies on the trunk means the last stage of disease development. Such a plant must be destroyed.

Actions of insect pests

If the diagnosis indicates that the tree is damaged by pests, then, as in the case with the treatment of fungal diseases, it is required to immediately place the sick plant in quarantine conditions. A course of rehabilitation consists of treating sick trees with pesticides according to the instructions. Particular attention should be paid to the permissibility of the use of certain pesticides at home and precautions. Remember that acaricide preparations are used to control mites, for other insect pests – interecticides of contact, fumigation and systemic action.

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