The most important job for a bonsai artist in the summer is watering. Giving water to these bonsai planted in small pots can prove to be quite tricky. It is such a vital skill that the first three years of a bonsai artist’s training is spent on watering. We will introduce this important skill in this issue.
In the winter bonsai will need to be watered around once a day, but in the summer, they need to be watered at least three times a day. The experience and knowledge of a bonsai artist are very important when watering; they will need to decide when exactly to water in the morning, at noon and in the evening, and how much water is needing when watering. The reason for this is because these will depend on a number of facotrs, such as the weather and the season, whether the bonsai is deciduous or not, the species, the age, how long it has been since it was repotted, the shape of the pot, and the qualities and condition of each individual bonsai. A bonsai artist must be able to determine all of these when watering.
For example, the amount of water needed in each season respectively for a broadleaf like a Japanese maple, that absorbs a lot of water in the growing season, and conifers such as a Japanese juniper, that do not lose leaves in the winter so transpire through their leaves, are completely different. Similarly, the amount of water needed and the time of watering will change depending on the qualities of each species, such as the Japanese apricot that buds with flowers faster than other deciduous trees, or the Japanese white pine, which originally grows naturally in high mountain climates.
Kaeshi-mizu is a word you may have not heard before. As bonsai pots tend to be shallow and flat, the roots of older trees will cover all the surface, making it hard for water to get to the bottom of the roots. If you gave water to a tree like this without much thought, the water would just flow from the sides at the top and would not reach the bottom of the inside of the pot. So, bonsai artists will water it once, and then water it again after waiting a little while. This technique, called kaeshi-mizu, allows for water to get through all the plant by spreading the watering out over multiple sessions.
The most important time to pay attention to watering is straight after repotting. During repotting, parts of the root have been cut off, so one could say that this period is similar to a person after a surgery. As the roots struggle to absorb water during this period, more water is given to the leaves to let it be absorbed through there. Sphagnum moss is also laid on top to ensure that the soil does not dry out.
Some may think that taking care of plants is easier than taking care of animals. However, bonsai are very delicate since they need to be cultivated under a specific environment. Our bonsai technicians at the museum will often patrol around the garden and the exhibition rooms, listening to the voice of each bonsai. This endless effort is the key to keeping bonsai alive and maintaining their beautiful forms.
Watering in the Bonsai Garden (outside) (Japanese white pine named "Maiko")
Watering in a zashiki room (inside) (Japanese maple)