Small Phoenix Bonsai Society Logo



  Introduction / Choosing Material

  Pruning & Shaping / Feeding & Watering

  Diseases, Prevention & Medicine / Roots, Pots & Soil Mixes

Display & Accessories / Hot Weather Care


(Presented by Bill Mooney & Leroy Fujii, 10/08/96)
When to Prune


        Determine the Basic Shape, either that which the untrained tree suggests or that which you want to give the tree.        What is the Front of the Tree?

  • Best view of trunk line, including good taper and, if not a formal upright, interesting curves which break up “telephone pole” appearance;
  • Best view of lower branches;
  • Least appearance of scars and other defects;
  • Best view of surface roots, which spread out evenly (but not perfectly symmetrical) around the tree.


  • Accentuates appearance and health of the main trunk and branches by removing unnecessary secondary growth;
  • Improves branch taper or shape by removing defects or extra length;
  • Improves exposure to light and air;
  • Improves proportions of overall plant by limiting the length of the branches;
  • Causes buds near the end of the branch to “break” and grow, resulting in ramification;
  • Causes buds closer to the inside to “break,” resulting in a filling in.  (Generally, have some leaves toward the end of the branch remain until more interior buds are viable and thriving.)

        Not pruning

  • Allows maximum growth on a branch, which increases its size or health due to an increased flow of auxin growth hormones to the growing tips.

        A non-symmetrical Triangular Shape is aesthetically most pleasing and natural looking, both for the overall tree and for the growth on individual branches.
        Ideally, all branches should be visible when you look down over the bonsai.
        Back branches add depth to the composition.

        Set branches in proportion to the overall tree.  The harmony of spaces is determined by the placement of the lower branches.  In 90% of the bonsai in Japan, a 10:1 ratio is seen: a 10″ high tree has a 1″ diameter trunk.
        Learn the flowering schedule of blooming trees so as to develop the limbs between flowering seasons.  Expose lots of branch lines.
        Initial Clean Up

  • Trim off small dead or broken branches.
  • “Bad” branches include: Large crossing, Pigeon-breasted or unevenly tapered, Bar, Spoke-wheel, and “U”-shaped.
  • Remove buds and small branches growing further down the trunk than the main branches.
  • Remove buds and small branches growing from underside of main branches, inside a curve, or in a branch/trunk junction.

        Frost-sensitive plants should get NO pruning after mid-October or so.  Do drastic pruning in February for most trees, maples by the end of January to avoid excessive bleeding of rising sap.


(Presented by Ernest Hasan, 11/12/96)

        Next to Pruning, Watering is the quickest/most decisive way to affect plant growth. Too much:  too much growth and too long growth, root rot, drowning, death (more plants are killed because of overwatering than from underwatering);

  • A little more than optimal: stimulation of new growth;
  • A little less than optimal: maintain growth on established plants; stimulate some plants to produce flowers;
  • Too little: new growth withers, dehydration, death.

        Learn individual watering needs, Amount and Frequency, the “Five S’s”:

  • Season = air temperature, humidity, dew point;
  • Siting = amount of direct sun/shade, wind, reflected light, ground moisture/cover;
  • Size = pot and plant, small/medium/large, shallow/tall, partly glazed/unglazed, weight when watered/dry;
  • Soil = grain-size, percentage of organic or other water-retaining material, texture & color when watered/dry;
  • State = newly transplanted or root pruned/established, newly pruned, healthy/sick.

        Allow the soil surface to be dry and even a slight wilting of leaves showing on some varieties before watering again, then water deeply and thoroughly.

        Quality: right from the tap (the worst); tap that has been sitting out 24 hours; sitting tap with a small amount of white vinegar added (1 tablespoon per gallon at least once a month); distilled; pond/aquarium; Reverse Osmosis (R.O.); rain (the best, but least likely to be gotten).

        Watering can be done from the bottom using a sink or tub, good for just a few plants.  From the top using a hose or watering can, good if you have several plants.   Foliar, good to clean dust and dirt off plants and cool the leaves, but best with distilled or R.O. so as not to put salt deposits on leaves.  Salt from tap water can build up on pots, trunk and roots and possibly cause leaf burn in some plants.  Azaleas and bald cypresses can be killed by hard water.

  • The Big 3:  N itrogen – P hosphorus – Potassium ( K ) are necessary, respectively, for Leaves & Stems – Roots & Flowers – Overall Health and Hardiness.
  • Micronutrients:  At least 15 other elements in smaller quantities are also vital for the life of plants.  S ulfur and Magnesium ( Mg ) are the two most important micronutrients.
  • Organic (less concentrated, slower acting, complex with other substances, e.g., fish emulsion, bone meal, blood meal) / Inorganic (concentrated, quicker acting, simpler/purer chemicals, e.g. MirAcid ® or Grow Power ® )

NOTE:    Bonsai is a continually evolving art, especially as practiced in a younger location such as the U.S.  There is some evidence now of potential harmful longterm effects of synthetic commercial fertilizers in bonsai soil mixes — for instance, the buildup of salts that are part of those fertilizers’ composition.  Based on our own positive longterm experiences with these blends in this unique environment, we offer caution about quitting their use just because it is recommended to do so elsewhere.  This is a subject which must be further investigated.  As we get a clearer picture of the best care for our desert growing trees we will include that information here.  

  • Full strength or Half strength or Gradual release (i.e., Osmocote ® or Grow Power ® )
  • Urea-based nitrogen fertilizers are slower released and safer acting.

        When to apply?  During growing seasons, not during dormancy, during pre-flower seasons.        If air temperature is under approx. 70 F, fertilizer acts very slowly;
        If air temperature is over approx. 90 F, fertilizer acts very quickly.

        Keep a log of your fertilizer application and results, if only for a single year.

        Finally, the concept of “feeding the soil” as opposed to just “feeding the tree” is one that needs further discussion in our circles.  Stay tuned.
        See also:  “The Limits of Fertilization” by Andy Walsh