Bonsai care is not complicated and is the basis for any successful bonsai design. The tasks to be carried out in the care of bonsai trees, such as watering and fertilization, are simple and basic techniques from horticulture and every garden owner is familiar with that.
There are a few simple basic rules of bonsai care that apply to almost all tree species. If you follow these guidelines, the care will be easy, your bonsai will grow, stay healthy and we can concentrate on the styling and forming.
Which basic rules of bonsai care are important ?
- Watering: Don't water too little or too much. It is best when the surface of the soil is slightly dry. In midsummer, outdoor bonsai sometimes have to be watered twice a day. Often not for several weeks in winter. Indoor bonsai need much less water in the apartment than outside in summer.
- Fertilization: All bonsai should be regularly supplied with an organic fertilizer in the growing season from March to September. Biogold, Hanagokoro and all commercially available liquid bonsai fertilizers have proven themselves. Azalea fertilizer is more suitable for azalea bonsai.
- Location: Trees need light to live. Lots of light. Therefore, bonsai should be placed on a bright place, especially indoor bonsai. Outdoor bonsai should not be cared for in the apartment.
- Overwintering: Outdoor bonsai should not be overwintered indoors. Indoor bonsai need a very bright and cool location in winter.
- Repotting: Repot your bonsai at the right time (beginning of March) in a well-drained substrate (e.g. Akadama, for azaleas Kanuma). Most trees need to be repotted every 3 years.
In addition to these brief instructions on bonsai care, which apply to all bonsai, there are specific things that are important for certain tree species.
These special bonsai care tips can be found at: Bonsai tree species
In the following we will go into the most important maintenance technics in more detail:
Watering is the most common bonsai care treatment. With a few exceptions, we have to water every day, often twice a day in midsummer. Accordingly, a bonsai can quickly suffer from incorrect pouring.
But why is irrigation so important to the tree ?
The nutrients absorbed by the root must be transported to the consumption points. For this the bonsai plant uses the water. The nutrients are dissolved in the water. The water evaporates at the stomata of the leaves, the nutrients remain in the bonsai and are used for cell building. New water with nutrients is taken up by the root cells and the cycle starts anew.
Moreover, if the bonsai is cared for too dry, it closes its stomata to reduce the evaporation of water. If the stomata are closed, it cannot absorb carbon dioxide to form sugar. Then it grows weaker. Therefore - water a bonsai regularly.
Proper watering is important in bonsai care. In this case, the middle is right for most bonsai. That means do not pour too little and also do not drown the plant. Moderately damp is optimal for most trees. If possible, do not use too cold water for irrigation. Cold water slows root growth for hours after watering.
More information about pouring as a bonsai care factor can be found at: Bonsai watering
Fertilizing is the second most common activity we are faced with in terms of bonsai care. Depending on the type of fertilizer we use, fertilization is carried out daily to monthly in the growing season from March to September. If not fertilized properly, the bonsai does not immediately die. But the tree is growing weaker. Why is that ?
Bonsai need building material = molecules to build up cells. These molecules take them up along with the water through the roots. During the growing season, fertilize your bonsai regularly with what the tree needs.
If, for example, a young bonsai plant or a prebonsai is to grow stormy in the cultivation phase to form a thick trunk, a lot of nitrogen must be given during the maintenance of bonsai. Amino acids are formed from nitrogen, proteins are formed from amino acids and proteins are basic building blocks of any cell. If you want growth - fertilize a bonsai nitrogen-rich and plenty.
When maintaining more mature bonsai or at the end of the growing season (September-October), fertilization is somewhat less nitrogenous. In these cases, a higher proportion of potassium and phosphate is beneficial for flowering and fruit ripening as well as for the wintering of hardy outdoor bonsai. But also here - don't let your bonsai "starve". Fertilizing is an important factor in bonsai care. Bonsai are not malnourished small plants.
More information about the fertilizing as a care factor can be found at: Bonsai fertilisation
The care of bonsai in winter does not differ significantly from the wintering of other, in pots held woody plants. In our opinion, the winter care of a bonsai is uncomplicated. Only a few basic points need to be considered.
First it must be clarified whether the Bonsai can be wintered as winter-hardy outdoor bonsai or not. Depending on the winter hardiness of your bonsai, the care in winter differs significantly. In case of doubt, ask your dealer or look under bonsai tree species.
Depending on the home climate of a tree species, bonsai are more or less winter-hardy or frost-resistant. Roughly speaking, bonsai species can be divided into 3 groups according to their winter hardiness:
- Not hardy: Species from tropical and subtropical areas are not hardy. In their home country, temperatures do not drop below 3-4°C. They are genetically unable to resist frost and cannot be accustomed to frost. Many indoor bonsai belong to this group.
- Low frost hardiness: Short-term temperatures around the freezing point are endured. Such species come from areas where light frost rarely occurs. We call such trees Mediterranean bonsai. Typical representatives of this group are Mediterranean tree species such as pomegranate, mulberry, olives, but also Sageretia, Podocarpus, Chinese elms, Chinese ash.
- Absolutely hardy: These bonsai come from areas with heavy frosts in winter. They can tolerate temperatures well below -10°C or lower in winter and are usually called outdoor bonsai.
How should bonsai be kept in winter ?
- Indoor bonsai: Very bright location directly at the window, if possible south side. Temperature not too warm, rather cool (10-20°C for e.g. Ficus bonsai, Jade tree bonsai, Snow rose) to cold (4-10°C for e.g. Privet, Pepper tree). Unheated, bright rooms such as bedrooms, stairwells, corridors are usually well suited.
- Mediterranean bonsai need protection from severe and prolonged frosts. Unheated conservatories are often optimal here. Only heat if the temperatures fall continuously and clearly under 0°C.
- Winter-hardy outdoor bonsai (Maple bonsai, Apple tree, Japanese azaleas, Hornbeams, Lime trees as well as White pine, Redwood and Elm tree bonsai) are well kept in foil tents or in unheated greenhouses. There they tolerate even the lowest temperatures. It is important to note that if the temperatures in the foil tent rise significantly above 0°C, ventilate them to lower the temperatures again. High temperatures lead to premature sprouting. Then even the hardest bonsai become frost-sensitive and can freeze to death.
Winter-hardy bonsai can also be sunken in the garden or - according to our experience - wintered outdoors in shade and sheltered from wind (like some Pine bonsai, Larches, Juniper).
More details about bonsai care in winter can be found under: Bonsai overwintering
The roots of bonsai are composed of cells and, like all other plant cells, they need oxygen. In order to reach enough oxygen to the root cells, the bonsai must be well drained.
In any case, avoid too fine bonsai soil. This is only suitable for covering as uppermost earth layer. Experienced bonsai friends often sift the fine parts, especially the dust, before repotting their bonsai.
The mycorrhizal fungi, which are important for many trees, are often added to the substrate.
Many bonsai soils disintegrate over time. In addition, the bonsai trees roots through the substrate more or less quickly. That is why bonsai care also includes regular repotting. When to repot depends on various factors.
When does a bonsai have to be repotted ?
- If the bonsai soil becomes too compact. Many bonsai substrates disintegrate over time and then have to be exchanged.
- If the root mass is too big for the bonsai pot. The roots are then reduced during repotting with rooting pruning.
- In the case of oxygen deficiency in the root area. Mostly when the bonsai soil is too fine.
- Pests have accumulated in the soil. Rarely a reason for repotting, but sometimes appropriate.
- In case of salinization of the soil, e.g. after overfertilization with a mineral fertilizer (nutrient salt).
The best time for repotting is early spring for most bonsai (late February to early March). Injuries to the roots can heal so quickly. Younger and fast growing trees are repotted every 1-2 years. For adult bonsai (styling is essentially complete) usually a 3-5 year rhythm is enought.
More detailed care instruction for repotting bonsai available at: Bonsai repotting
Location, light, temperature
Bonsai, like all plants, gain their energy from light. They do this by photosynthesis. Light is the most important bonsai care factor. Always set up bonsai plants brightly.
In particular in case of indoor bonsai in the apartment, the light plays a crucial role. A normal glass pane reduces the light significantly. Today's double and triple glazing, the light supply is already greatly reduced. Then if there is only a north window available for the bonsai tree in the dark season (i.e. the days are shorter than the nights) the trees reach their limit. Then they often throw off leaves. Especially when the temperatures are high at the same time.
All processes in a living plant are temperature dependent. That means the higher the temperature the faster the metabolic processes run. A 10°C higher temperature doubles the metabolism.
The temperature is hardly considered in bonsai care but plays a crucial role. If your tree do not get enough light in the apartment during the winter months, it can barely gain enough energy. If you want to help your bonsai - place it cool so that the metabolism (the energy consumed) is not too high.
In midsummer it can make sense to shade bonsai, especially very small bonsai. The reason is: The bonsai pots can get extremely hot in the summer heat. 50°C or more on the sunny side are possible. A big problem for the roots of a bonsai tree. The roots often die on the sunny side.
My bonsai loses leaves - what can I do ?
A question which is often be written in every bonsai message board. Leaf shedding on a bonsai tree has been experienced by almost every bonsai enthusiast. With a little background knowledge it loses his importance or the leaf shedding is completely avoidable.
Why a bonsai drops leaves, whether and what you can do can be found at: Bonsai losing leaves