Bonsai are generally considered to be somewhat difficult housemates. Their care requires precise knowledge and if treated incorrectly, the miniature trees quickly drop their leaves and die. You can read about the reasons for this here.
Those who have little experience with the care of a bonsai tree are quickly unsettled when the plant shows signs of leaf loss. And rightly so, because usually a loss of leaves in a bonsai is a warning signal that something is wrong, and yet no reason to panic. If you read up a little on proper bonsai care before you buy, you can enjoy the little beauty a lot later on and avoid care recommendations. Here are some reasons why your bonsai may suddenly lose its leaves, and what measures you can take if your bonsai’s leaves fall off.
Why does the bonsai lose its leaves?
Are you watering the bonsai properly?
As is often the case, leaf fall on houseplants can be an indication of improper watering. Cheap hardware store bonsai in particular are often in pots that are too small with a substrate that is too firm and lacks a drainage hole, which creates a number of watering problems. So be sure to transplant a new bonsai into a tray with a drainage hole and structurally stable, permeable substrate. Then, pay attention to the following when watering your bonsai. Bonsai stand in very small bowls. This restriction of the root space ensures, among other things, that the trees remain small. However, this also means that there is very little water-retaining substrate in the planting tray from which the plant can obtain its water.
Depending on the bonsai design, watering from above is often difficult. Therefore, it is better to dip the planting tray once a week so that the entire root ball is well moistened. Let the excess water drain off well afterwards. Before the next watering, the top layer of soil should be thoroughly dry. The far bigger problem, however, is too much watering, because if the bonsai is permanently too wet, the roots will rot and the tree will be lost. A root ball that is too wet is one of the few good reasons to repot the bonsai quickly into fresh, dry soil. Remove rotten roots and water rather sparingly in the near future.
Is the bonsai in the right place?
All bonsai are very light-hungry. Therefore, place the small trees in as bright a place as possible without direct sunlight. Some species tolerate morning and evening sun, but you should protect all bonsai, indoor and outdoor, from blazing midday sun. If the bonsai suddenly loses its leaves in the fall, it may be that the usual location no longer provides enough light in the deteriorating light conditions of winter. The bonsai will then react by shedding its inner crown leaves, as they consume more energy than they generate from photosynthesis. If this is the case, find a brighter place for your bonsai in winter with a more favorable angle of light incidence. For delicate or valuable specimens, it is worth using a plant lamp during the dark season.
Is the bonsai fertilized according to its needs?
If you fertilize your bonsai with mineral liquid fertilizer or nutrient salts, you should follow the manufacturer’s dosage instructions exactly. It is better to fertilize your bonsai a little less than too much. Because if excessive amounts of nutrient salts accumulate in the substrate, the roots can no longer absorb water and will burn under the salt load, and the bonsai will react by dropping its leaves. To save the tree, you should remove the old substrate, rinse the roots well, and possibly prune them back a bit. Then put the bonsai in fresh soil and do without fertilizer for a while. Organic liquid fertilizer is free of accumulating substances and therefore practically never leads to overfertilization if handled carefully.
Was there a change of location?
Who hasn’t experienced this? No sooner have you carried your new houseplant home from the store and placed it by the window than it begins to shed its green leaves. This is a natural reaction that is particularly common with bonsai. The loss of leaves here is the result of the change of location from the greenhouse, garden center or hardware store to the home four walls. During such a move, the bonsai’s entire living conditions change, light, temperature, humidity, watering frequencies and much more. Such a change means great stress for the small plant and leads quite naturally at first to leaf fall.
Such a stress reaction can also occur with sensitive plants or varieties prone to leaf drop. For example, the Benjamin’s fig, when moving from one room to another or from outdoors to indoors. Don’t make the mistake of moving the tree again now, but give it enough time to get used to its new location. Since many bonsai are sensitive to relocation, think carefully about the right place for the plant before moving it and leave it alone for now after the move.
Is the bonsai sick or infested with pests?
Of course, as with any houseplant, pest infestation, harmful fungi or plant diseases can be responsible for the bonsai losing its leaves. However, this occurs relatively rarely with bonsai. If you suspect your bonsai may be diseased, seek help from a professional to accurately identify the disease before treating the plant. Many bonsai, especially exotic ones, are sensitive to pesticides, which can do more damage to the little trees than cure them. Pests should be picked off, washed off, or controlled with natural remedies.
Outdoor bonsai: leaf fall in autumn
Outdoor bonsai represent a special case in bonsai care. These usually somewhat larger specimens of weather-resistant deciduous and coniferous trees are much more exposed to the changing seasons than indoor bonsai. So it’s natural for deciduous trees to shed their leaves in the fall, just as their larger siblings do in the garden. Even conifers such as larch (Larix) or redwood (Metasequoia glyptostroboides) sometimes lose their foliage in the fall and winter. This is a completely natural process and not a maintenance error. In spring, these trees will reliably sprout again if properly overwintered.