The popularity of indoor bonsai trees is increasing among beginners in temperate climates. These indoor bonsai trees are tropical or sub-tropical plants. They are tender plants that have to be grown indoors the whole year in temperate climates since they require a lot of care. Nevertheless, if you live in a warm climate, you may be able to grow them outside as well.
The first step is to select species that are suitable for indoor cultivation.
Indoor bonsai are located and cared for according to their native habitat’s climate. The climate in which the tree originated determines the bonsai’s needs, tolerances, and sensitivity to the environment.
With experience you will be able to understand better how various components of the environment interact with each other and affect your indoor bonsai tree. For example, exposing your indoor bonsai to high light will also expose the tree to increased room temperatures. The higher the room temperature, the greater the need for water, and so on.
Indoor bonsai tree care can be divided into 2 components:
- Environmental factors – Light, Temperature, Humidity, Air
- Care and maintenance – Watering, Feeding, Soil, Pruning, Repotting, Pest Control
Lets have a look at all these factors one-by-one.
Light
When choosing an indoor location for your bonsai, you need to pay special attention to ensuring that the bonsai receives the right amount of light.
A bonsai placed in a location with insufficient light will show symptoms like leggy growth, increase in size of leaves, increase in the distance between internodes, and growing tips becoming black (don’t confuse this with frost damage).
Generally speaking, as far as light requirements are concerned, trees fall into one of three broad categories:
- Low light: Just enough light in a room to read newsprint.
- Medium light: Sunlight from a south or west window in spring
- Bright light: An outdoor summer day with clear skies.
Please read amount of light required by various indoor bonsai tree species to know exactly how much light your indoor bonsai tree will need and which bonsai is suitable for your home lighting conditions.
Artificial light can be used to supplement inadequate natural light. Please read how to grow indoor bonsai tree using artificial light for more details.
Artificial lights are specially useful in winter months of temperate regions. The days are simply too short and bonsai doesn’t receive enough light even in the windowsill. Artificial lights can help you simulate long days in winter months. It is also advised to use these lights with automatic switches fitted with timers.
Few things you will need to keep in mind before finalizing a location:
- Don’t keep the bonsai behind a glass of the window. The area behind a pane of glass becomes very hot when the sun shines directly on it.
- The midday sun can be harmful even to plants that need plenty of light. Hence avoid a location where the bonsai will be exposed to direct sunlight for a prolonged period of time.
- Do not equate the light emitted by incandescent lamps with natural light. Incandescent lamps do not produce a full spectrum light which is suitable for the growth of a plant.
- Make sure that the window is not obstructed by large trees, high walls, or a roof overhang.
- Even 1 meter (3 feet) away from a window, the degree of luminosity diminishes greatly, although this is not noticed by our eyes. For an indoor bonsai, that might already be too dark.
How do I know if my bonsai is getting enough light?
One of the telltale signs of whether the bonsai is receiving enough light is an increase in the size of the leaves and an increase in the distance between the leaves on new shoots. A bonsai that is not receiving enough light will elongate its shoots in the search for light and the size of the leaves will also increase to gather as much light as possible. This will also make the bonsai look unsightly.
If you notice these symptoms, either move the bonsai to a brighter location or use grow lights.
Which direction should bonsai plants be kept?
The best direction I would recommend is a large south facing window. This location will provide maximum light exposure for the bonsai. Another recommended location can be near a west facing window. This location will have plenty of sunlight in the afternoon and some direct sunlight in the later hours of the day. Plenty of light and minimal direct sunlight makes this ideal location for a lot of indoor bonsai trees.
Can bonsai trees grow in low light?
Yes. There are few bonsai tree species which can be grown in low light levels such as schefflera actinophylla – Australian umbrella tree bonsai, Hedera helix – English ivy tree, Cissus antarctica – Kangaroo vine bonsai tree, Rhododendron – Satsuki Azalea bonsai, Cissus antarctica – Kangaroo vine bonsai tree, Citrus – Citrus bonsai etc.
Click here to an extensive list of indoor bonsai trees and minimum light levels required by them.
Can bonsai grow in indirect light?
Yes bonsai can grow in indirect sunlight. In fact, it is recommended that some indoor bonsai trees be grown in indirect sunlight. Providing indirect sunlight is especially critical during the height of the summer season. At this time the foliage of the bonsai can scorch.
How much sunlight does bonsai tree need?
Even for the most sun-hungry bonsai trees, daily sunlight exposure of 5-6 hours should be good. For the rest of the day, trees can be grown in indirect sunlight or partial shade. Use a light-transmitting shade or adjust window blinds to protect the bonsai from direct hot sunlight.
Temperature
As we have established already, all the indoor bonsai trees have either subtropical or tropical origins.
It’s recommended to keep tropical plants at a constant high temperature between 65°F and 75°F (18°C and 24°C). Additionally, lower their nighttime temperature by a few degrees, though it should not fall below 61°F (16°C) at all times.
It is perfectly fine to place tropical bonsai trees near a window or above the central heating system (However, placing the bonsai on very hot places can also lead to excessive heating of bonsai soil, which will cause the woody parts of the tree to develop heat canker). In spite of this, check your window coverings and blinds because if they are heavy, they can trap cold penetrating from outside and disperse heat from the window area.
For subtropical bonsai tree varieties, the suitable temperature for bonsai varies depending on the season – especially in winter and summer.
It is okay to keep these plants in the open during the summer months, but they must be protected from the wind. During the later portion of the year, however, they must be brought back inside as soon as the nighttime temperature drops to 50°F (10°C), although some bonsai will tolerate lower temperatures for very short periods.
During the winter, they should be placed in a well ventilated location, with temperatures ranging from 54°F (12°C) to 41°F (5°C). It is ideal to place these plants in unheated conservatories, frost-free greenhouses, unheated rooms, and corridors.
It is possible to place tropical and subtropical bonsai trees outdoors in the summer. However, moving the bonsai outside should be gradual. Let the bonsai get acclimatized to the variation in light gradually. Begin by putting them outside for short periods, and then increase the amount of time they spend outside each day by half an hour.
The warmer the position, the more light the plant needs. An increase in temperature will also result in a greater need for water.
The mentioned temperature ranges are just rough guidelines. As you spend more time with your bonsai, with experience you will learn in which temperature range your bonsai grows best. Also, please check out types of bonsai tree species to see individual specifications for each tree.
Humidity
Indoor trees require high humidity and warm conditions, which is difficult to achieve in centrally heated houses.
The bonsai will suffer if it is placed in too dry conditions. As a result, it will quickly lose more water than its roots can absorb, eventually interfering with the exchange of gases between its leaves and the atmosphere. Growth of the bonsai will also be affected in this way.
The more humid the atmosphere, the less water the tree needs. On the other hand, if the air is dry, the plant will need a lot of water.
Achieving the right humidity level can be a tricky business, but with patience and trial and error you will succeed. It is always helpful to own a hygrometer (humidity meter) if you are a bonsai grower.
Each species has its own requirements for humidity.
A plant that has waxy leaves, such as the fig, is better protected from dry air than a plant with tender and herbaceous leaves, such as yellow sage.
Do bonsai like high humidity?
Yes indoor bonsai trees prefer high humidity. It is generally recommended to keep indoor bonsai at a humidity level of 40-50%.
How do I keep my indoor Bonsai humid?
You can increase the humidity of the room for your bonsai by following ways:
- You can use an electric humidifier.
- Place a bowl filled with water close to the bonsai tree.
- Place the bonsai container on a tray filled with moistened pebbles. Have the water level on the tray below the height of the pebbles so that the bonsai pot is not sitting on water, rather on the wet pebbles.
- Keep the room where you place your bonsai cooler than the rest of your home. Air conditioning, which removes moisture from the air, is best left off or at a low setting during the summer months.
- Having plenty of houseplants, which constantly release moisture into the room can also be a little helpful.
- A room with an aquarium is also likely to have high humidity.
- A simple frame covered with clear plastic can be used to cover the bonsai tree. This trick is used by many bonsai growers to increase the humidity around the bonsai tree. However, make sure that bonsai is not completely sealed or else it will become prone to fungal attacks.
- Frequently misting the growing area raises humidity temporarily, but is often impractical and may increase disease outbreaks. Furthermore, not all bonsai trees can be misted. Also, in certain situations, misting is not recommended, such as – when the tree is flowering. Please check the individual care guide of bonsai tree species to know which bonsai tree can be misted.
Misting and washing the bonsai with luke warm water in a tub once a month will also help remove dust and allow the leaves to breathe.
Air
The sluggish airflow in homes and apartments, coupled with the delicate leaves of bonsai, makes them easy prey for pests and diseases.
Do bonsai need wind?
As trees grow in the open air, wind and weather ensure that their leaves are robust. As a result, they are better protected from excessive evaporation and pest infestation. This alone makes it a wise idea to keep the bonsai trees outside for a time during the summer, either on a balcony or in the garden. In the event that this is not possible, a fan placed near the bonsai and allowed to run for a few hours every day will achieve the same effect.
Unless your bonsai is extremely tender, fresh air shouldn’t harm it in the summer. During the winter, however, you should make sure that the plants are not exposed to direct cold air or drafts (at this time keep the windows closed or move the bonsai away from the window).
Watering
How often should I water my indoor bonsai tree?
Do not stick to a fixed routine of watering your bonsai. Instead “listen to your bonsai” and water the bonsai when it “tells you too“. You should check your bonsai every day to see if it needs water. You can check the soil in the container by checking the color of the soil, bearing in mind that the plant should be watered before it completely dries out (the lighter the soil color, the drier it is). Or you can touch the soil, if it feels dry to the touch, you should water the bonsai.
How do you water an indoor Bonsai tree?
Water the soil slowly, with brief interruptions, to allow it to permeate completely. Stop watering when you see water seeping out of the drainage hole.
When the soil is too dry, the water won’t be absorbed and will spill over the side of the bonsai container. To water such bonsai trees, you can use the immersion technique. Submerge the bonsai container in water and keep it there till you notice that small air bubbles have stop emerging from the bonsai soil.
For plants exposed to the sun, especially during the summer, the “shower” effect, which damages the leaves, should be avoided. Spraying mist on them should be avoided in the afternoon. The droplets of water on the foliage will act as mini lenses and will focus intense sunlight, causing scorching of leaves. Even in the evening these droplets can pose some problems. If the drops do not dry out before the onset of the cooler night-time air, the foliage could become more prone to disease from fungal or bacterial attack.
Each variety of bonsai requires a different amount of water, so you should thoroughly understand their habits. In addition, bonsai placed close to central heating will require more frequent watering, just as they do during their growing season.
You can refer to types of bonsai page to know the watering requirements of various bonsai trees. Also please refer to watering bonsai for an in-depth guide on types of water for bonsai, bonsai watering methods and tricks and tips.
Feeding
When compared with a normal houseplant, an indoor bonsai has access to a smaller amount of soil. Therefore, it needs to be fed properly in order to stay healthy.
If you feed your plants regularly, you will ensure that they receive an adequate supply of the three main nutrients they require: nitrogen, phosphorus, and potassium. A number of fertilizers also contain trace elements such as boron, copper, and manganese, which are essential for plant growth.
In order to avoid damage to plants caused by inappropriate fertilizer use, the following rules should be observed when using fertilizers:
- Fertilizer should never be applied to dry soil. A plant should be watered generously before being fed.
- Use inorganic fertilizers at a lower concentration than suggested by the manufacturer. To compensate for the lower doses, feed the bonsai more frequently.
- Rinse the root ball thoroughly with water if you applied too much fertilizer by mistake.
- A newly repotted bonsai should not be fed for at least two weeks, since its new soil has adequate nutrient reserves.
- Because bonsai trees are largely inactive during the winter, winter feeding should be more sparing.
- It is always advisable to feed liquid fertilizers to bonsai trees that have been severely deprived of nutrients.
It is also important to consider the specific requirements of individual plants in addition to these general rules. Please refer to individual care guides in types of bonsai trees.
Also read the detailed guide on how to fertilize a bonsai tree for more details.
Soil
Most woody plants tolerate a wide variety of naturally occurring soil types. There are, however, some bonsai trees that require quite specific soil conditions.
A soil’s qualities are largely determined by its composition, pH value, and texture. Generally, bonsai soil consists of a combination of various materials such as Loam, Sand, Lava, Peat, Potting compost, and Azalea.
There is more information about the soil requirements of individual plant species in the bonsai tree species guide.
Also check out the bonsai soil guide to learn more about bonsai soil components and various soil recipes you can make for your bonsai.
Repotting
When should I repot my indoor Bonsai tree?
An indoor bonsai needs to be repotted and root pruned every one to three years, depending on the species, the growth pattern, and the soil composition. Species that grow rapidly, such as figs [Ficus species], may require repotting every year, while trees that grow slower, such as black olives [Bucida molinetit], may need repotting every three to five years.
In general, older and more mature bonsai require less frequent repotting because they grow slower and are less likely to become root-bound as quickly as young trees.
Whenever the tree is repotted, it’s important to remove just the right amount of roots, and that requires a delicate balance. The tree dies if too much of its root mass is removed, since it cannot absorb enough water to stay hydrated. If too little roots are removed, the bonsai will grow longer and longer, requiring a larger pot.
The best rule of thumb you can follow if you are not an experienced bonsai grower is to prune 20-30% of the roots at the time of repotting.
Read how to repot a bonsai for a detailed guide on repotting a bonsai. It will also give you the information how to perform root pruning.
Also refer to various types of bonsai tree species to know the best time, how to, root pruning and pot requirements of individual bonsai tree species.
Pruning
Bonsai pruning is done for two reasons. Firstly, pruning is done for the general health of the tree, secondly, to maintain its shape or improve its aesthetics.
Tropical and sub-tropical bonsai trees will require periodic pinching and trimming throughout the year. Due to the fact that trees grow at different rates, you must adjust your trimming and pinching to accommodate each tree’s growth rate.
Pruning is divided into structural pruning and maintenance pruning. These will include bud pruning, shoot pruning, leaf pruning and branch pruning. Make sure to use the right pruning tools. Knowing how to use a pruning tool is very important, since every tool has a specific purpose.
Please refer to the detailed guide on how to prune a bonsai to know everything about pruning and best practices.
IMP: Although wire bonsai training is not generally considered in bonsai tree care, knowing how to wire a bonsai tree is a wise idea also.
Pest and diseases
As with any other tree, shrub, or houseplant, bonsai trees are also susceptible to pests and diseases.
As long as trees are properly cared for and maintained, pests and diseases should not be a problem. Please read how to keep your bonsai tree pest free.
In contrast to other large tree and shrub forms growing in the wild, bonsai tree pests and diseases can be controlled manually, such as by removing insects by hand or moving the tree away from insect-infested areas or just trimming the infected area, thereby reducing the need to use chemicals.
Although diseases and pests can be very concerning subjects, most bonsai are quite trouble-free, except for succumbing to common issues such as aphids, caterpillars, mildew, rot and rust. Nevertheless, there are a few diseases that, if not stopped in the early stages, may negatively affect not only the host bonsai but also the entire collection.
A detailed guide to all the bonsai tree pests and diseases will help you in determining the symptoms of an infection. Furthermore, it will provide you with organic and inorganic solutions that can be used to fix the problem.
