Monthly Tasks – June

Based on San Francisco Bay Area Climate

by Mitsuo Umehara

Early June

Correct way to water a bonsai
Correct way to water a bonsai
  1. Watering is the most important task now
    Train yourself not only to see, but to able to FEEL the degrees of dryness on each tree and water appropriately. When in doubt, push a chopstick into the soil near the edge of the pot. After you remove the chopstick touch it. If it feels dry then it is time to water. Consider adding a tag on trees needing special attention as a reminder. For details see Watering Basics article.
  2. Inspect and treat your trees for insects
    1. Look for the Juniper Twig Girdler that kills Juniper branchlets. This pest is a major problem for many club members.
      Capitol Bonsai (Sacramento, CA) has a great article about how to inspect and treat for this problem – see article.
    2. Caterpillars eat deciduous leaves.
    3. Scale insects, pine bark aphids, chermis, moths (primarily a concern for Satsuki azaleas), and red spider mites will attach your trees. Keep watchful eyes for them and spray as they appear before they do any harm.
    4. Ultrafine or similar sprays will handle most pests, but may not be effective on Juniper Twig Girdler. Pyrethrin spray may work better, and is fairly safe – except you need to avoid exposing cats, fish and bees. You need to spray twice – in early June and mid-July to kill Girdlers.
    5. More info at Pest and Fungus Control Basics
  3. Wire new growth on deciduous trees – This type of wiring is done only where it is needed for the sake of looks. One month is all that is needed to train such young branchlets; so don’t forget to remove the wire.
  4. Junipers – Eliminate yellowed needles from Shimpaku, cut back, work on jins and wire.


  1. Transplanting – Early summer is the second season to transplant
    1. Five-needle pine – When the needles on new candles start to open, you may begin to transplant and can continue transplanting for a month after that. Remember to mix in some mycorrhiza (white root bacteria) from old soil
    2. Other Trees – Follow spring instructions for transplanting other plants missed during that time.


  1. Cut back overgrown grasses, Zebra grass, Blood grass, etc. It will look nice in the fall, perfect to appreciate the colors. For SASA bamboo, pull the core/center out to control its height.
  2. All transplanting of Satsuki should be done by the end of this month. Some Satsuki varieties bloom late. Do not transplant these until next spring in March. However, after care must be given in same manner as the other.
Scroll to Top