Monthly Tasks – May

Based on San Francisco Bay Area Climate

by Mitsuo Umehara

Early May

  1. Leaf Cutting – Why do we do this?
    • To produce smaller leaves.
    • To make fine, delicate branchlets in short term.
    • Opportunity to renew damaged leaves.
    • Allows transplanting, if needed.
    • Note: Ten days prior to leaf cutting, apply liquid fertilizer to tree to give extra strength.
  2. Maples
    • On outer, larger leaves, cut the leaf off completely (defoliation), leaving part of the petiole attached to the branch. (Figure 1)
    • On mid-sized leaves, cut half of the leaf off the petiole. (Figure 2)
    • On small, inner leaves, do not cut anything. (Figure 3)
Figure 1Figure 2Figure 3
  1. Trident Maple – cut only the large leaves.
  2. Elms – Hold the tip of a branch securely with one hand and draw the leaves backwards through the fingers of the other hand — pulling off the leaves with your fingers. Mass elimination of leaves using this method does not harm the tree.
  3. After Care – Reduce watering for a couple of weeks, but spray-mist branches in the morning and late afternoon. Rotate the pot frequently for even sunlight exposure.
  4. Fertilizing – Time to give second application of fertilizer for the following trees:
    • Black pine being cultivated for short needles
    • Ume, crape myrtle, willow, and other trees being cut back for the purpose of inducing secondary buds
    • Berry/fruit trees — only after the fruit has set.
  5. Pruning to Maintain Shape
    Removing the tip of new growth is done to keep the branch from getting too long, and to force new growth further back on the branch. Cut new growth off using small scissors. The important thing to remember is not to remove very much at a time, and only when the tree is very healthy. Here are some guidelines:
    • Ume, crape myrtle, willow, and other trees should be cut back to induce secondary buds
    • Berry/fruit trees – cut back only after the “bearing” has been confirmed.
    • Shimpaku, needle and other junipers plus cryptomeria (cypress) – trim tips from now through the end of September.
  6. Summer Cuttings – An ideal time to take the cuttings of Miyama-Kirishima azaleas, elms, maples, and camellias. Cuttings of four to five inches long can be made from this year’s growth once it’s hardened. Eliminate leaves from the lower half of stems, soak in water for 20 minutes. The remaining leaves on the upper half should be reduced to one-half leaf by cutting the tip off. Dip the bottom of the stem in Rootone to cover the cut surface. Insert the cuttings 1-1/2 inches deep in the soil mixture of one-half sand and one-half #6 perlite. Keep moist by spraying and protect in a frame house for two weeks. Slowly reduce the moisture and gradually increase the sunlight. Within two months, all should be rooted.
  7. Air-layering– Now through July is the best time to air-layer maples, trident maple, stewartia, elms, quince bittersweet, pomegranate, crape myrtle, and apples.


  1. Satsuki Azaleas – Early summer is the second season to transplant
    1. Before Satsuki start to bloom, spray with fungicide to prevent flower-blight disease.
    2. During the bloom, protect flowers in the semi-shaded area.
    3. Be careful not to wet the flowers when watering.
  2. Pine Candle Cutting – If you haven’t cut candles yet see Black Pine Basics for details.


  1. Deciduous trees (beech, birch, stewartia, etc.) should be protected from the wind and westerly sun if you want to enjoy the fall color. Change the location or make special shades for them.
  2. Some trees dry out more than others. They should be submerged in a tub of water periodically to give a good soak.
  3. Satsuki should have flowers removed before they wither. It is hard for the trees to keep the blooms for a long period.
  4. Perform bud nipping, eliminate excess branches, and shape the trees. Transplanting should be done every other year.
Scroll to Top