The Japanese zelkova, or Zelkova serrata, is a graceful tree belonging to the elm family. This deciduous tree has a moderate to rapid growth rate and adjusts well to most soil environments. It produces rich green foliage that turn to showy hues of coppers, reds and yellows in the fall. The adaptability and showy presentation of the tree make the Japanese zelkova an ideal selection for bonsai.
Choose a deep, well-drained potting container for your Japanese zelkova. Select a container with a depth that is slightly larger than the diameter of the zelkova’s trunk. Choose a container that is as wide as the diameter of the tree’s canopy, recommends Bonsai4me. Use a container with at least one drainage hole at the bottom of the container to allow the excess water to escape.
Plant your zelkova in nutrient-rich, loamy soil. Incorporate equal parts of nutrient-rich potting soil, organic compost and clean, fine sand. Mix the elements thoroughly to promote well-balanced, water retentive but well-drained soil.
Cover the drainage holes with a thin layer of fine mesh to prevent the roots and soil from exiting the container. Line the bottom of the container with a layer of soil. Position the Japanese zelkova in the center of the container and fill the container the rest of the way with soil. Press the soil firmly around the zelkova.
Irrigate your newly planted zelkova bonsai thoroughly. Water the tree with tepid water at soil level. Irrigate the bonsai until the water flows evenly from the bottom of the container, and then allow it to rest until the water no longer drips from the container.
Water your zelkova bonsai based on its needs, rather than on a schedule. Check the soil moisture level daily and only irrigate your zelkova when the soil feels somewhat dry. Place your finger in the soil near the roots to check moisture levels. Irrigate your bonsai in the same manner as when you completed its potting.
Place your Japanese zelkova bonsai in a warm, sunny location. Ensure that the location receives at least six hours of full sunlight each day, if not a full day’s light. Keep your bonsai away from drafty doorways and other areas with drastic temperature variations.
Fertilize your Japanese zelkova bonsai regularly throughout the growing season, from early spring through late fall. Use a well-balanced, water-soluble fertilizer with higher nitrogen levels, such as a 10-10-10 or 12-12-12 combination. Feed your zelkova biweekly and according to the instructions to prevent over-fertilizing.
Prune the foliage of your zelkova during the summer. Remove the foliage by gently snapping the foliage from the base of the stem. Complete your hard pruning process during the dormancy period. Remove any unwanted, dead or damaged branches and stems using sharp, sterile pruning shears.