Japanese Holly Bonsai Care Guide

Japanese holly bonsai trees can be grown both indoors and outdoors, depending on where you live and your preference. It prefers a temperate climate and can tolerate most conditions but avoid harsh sun or heat in warmer months, and frost in the winter. If placing outside, choose a location that receives ample sunlight throughout the day, but provide semi-shade during the midday when the sun is at its strongest to prevent leaf burn. In the winter months, protect your tree from frost and strong winds, and consider using a cold frame or bringing it indoors to an unheated space such as a greenhouse to allow for its dormancy period. Cooler temperatures that do not fall below 5 °C are ideal for this.

If placing indoors, choose a windowsill that gets plenty of sunlight. Japanese holly bonsai trees can tolerate low light conditions, but this may result in slower growth and discolouration of the leaves. If you need to place your bonsai tree in a location with lower light levels, consider supplementing with artificial grow lights to provide adequate energy for healthy growth. Keep in mind that Japanese holly bonsai trees are sensitive to temperature changes, so it is best to avoid placing your tree in areas with cold draughts or exposure to artificial heat sources such as radiators. 

There is no definitive guide to watering and it should be conducted on an observational schedule, not a routine. This means that it is important to keep an eye on the moisture levels of the soil to avoid over and under watering, both which can lead to dropping leaves and/or root death. The amount of water a bonsai requires depends on pot size, climate, airflow, soil and tree type so it is best to use your eyes and fingers to assess whether the soil is damp, wet or dry. 

If the top inch or so of soil has dried, it is ready to be watered. When you water, try to get an even coverage over the roots and soil, allowing water to flow out from the bottom of the pot to ensure a good soaking.

If you are a first-time bonsai owner, another way to water is by submerging the entire pot in water until the bubbles stop. If you choose this method, be aware that your bonsai may not need watering for another two to four days, but this will depend on the factors mentioned above such as soil type, pot size and climate.    

The Japanese holly also benefits from slightly higher humidity levels. This can be achieved by using a mister to spray the leaves, as well as placing a gravel tray under the pot to create a more humid microclimate around the tree.

Using fertiliser on your Japanese holly will help encourage healthy growth and this should be done periodically from once a week to every two months and only during the growing season. You can start adding Chrysal Liquid Bonsai Feed to your water from March until October and use weekly. Use Naruko Fertiliser Slow Release Bonsai Feed once every one to two months. With Buddhist Pine trees, less is more, and we tend to advise using half the recommended dosage to see how your Buddhist Pine reacts first.

Pruning your bonsai is important not only to maintain or create an aesthetic style but to also ensure light and airflow can reach inner leaves and the Japanese holly tolerates constant pruning very well. During the early to late spring months use appropriate tools to cut back stems which have grown longer than four leaves, leaving the two leaves which are closest to the stem intact. You can repeat this process when new stems appear after pruning. If you are looking to encourage flowers and fruits, stop pruning your Japanese holly in early summer.

Training your bonsai using wiring is best done during the later spring and summer months growing period when the stems and branches are easier to bend. Wiring a Japanese holly can be slightly challenging as the branches are brittle and the bark can be damaged, so take care not to wrap wire too tightly and risk loss of circulation or scarring. We recommend using wires with a thickness that matches the thickness of the branch: if the wire you choose is too thick you will damage the bark. If it is too thin, it won’t be effective.

Repotting your tree is an important way to provide a fresh and suitable soil mix and ensure appropriate root health. Repot in early spring. Generally, your Japanese holly will need to be re-potted once every two years if it is young, while older ones can stay in their pots for longer. However, you should always check if it has become root-bound before you change pots. You can do this by lifting the tree gently out of the pot by the main trunk and examining the root system. You will know it is ready if you can see that the roots are circling around each other and the pot. If, however, they still appear contained in the soil, you should place it back and wait until the following spring to check again.    

Trees that are ready for repotting will require root pruning, a suitable new pot and appropriate soil mix.

When repotting, do not cut back the root mass by a large amount, and choose a well-draining soil mix that has a neutral or slightly higher PH value of 5-6 but not over 7. We tend to use a mixture of different speciality bonsai soils on our trees. Every species is different so please contact us for free soil-mix advice or to take advantage of our repotting service.