The Taskmaster (aka Chris Ross) explains what to do, how to do it and why for bonsaists in the San Francisco Bay Area.
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June
June in the Northern California microclimates is a time for bonsai artists to be watchful and careful. Watchful because it is a time of rapid growth and careful because of the weather.
Rapid growth means unlimited opportunities for bugs and pests. Spray every week or two with a good fungicide or insecticide in the very early morning or late in the afternoon. Be careful not to use a very strong solution, and water the soil in the pots copiously later on to wash the drips and runoff from the soil. Spray with a strong stream of water just to knock the bugs all off every few days (a very effective strategy against spider mites and aphids), and use safer soap now and the just for good measure (you can make your own with a teaspoon of liquid dish detergent to a quart of water).
Rapid growth also means pinching back the growth of all trees to preserve shape, create shorter internodes, better Fall color, and smaller leaves. Deciduous trees can be defoliated now if they are healthy, except for beech trees, which may die off or not grow back. Cut off the leaves and leave the leaf stems, or petioles, to feed the new leaves, and leave the interior and smaller leaves alone.
Let them grow!
This treatment is for mature, finished, or well-shaped trees, and not for material in development. Pinch out only the center primary tip on evergreens, to promote backbudding and thickening of the pads. Stop feeding defoliated and heavily pinched trees for three weeks, reduce water drastically, and put them in partial shade or morning sun only for two or three weeks with no fertilizer, then bring them out again slowly.
Rapid growth now can mean windburn, quick drying, and sunburn, so be especially vigilant about protection. Scratch and penetrate the soils with a chopstick to encourage draining and oxygen uptake, Cover or shade the pots, especially the smaller ones, and consider spraying with Cloud Cover or similar products to reduce drying in our frequent winds, and with Eleanor’s VF-11 to foliar feed.
Rapid growth means a golden opportunity to air layer just about anything, but do it in the first half of the month before growth slows. Talk to someone who knows how or find a good article to read and go create some new trees, for free!
When the azaleas are finally nearing the finish of blooming, cut off all remaining blossoms, remove all seed stems from old blossom sites, prune all leafing branch tips to two stems, or terminal branchlets, and prune away all unwanted growth smaller than a quarter inch. Gently, loosely wire all the new Spring growth, but remember to check all wires in five to eight weeks for probable removal.
Pines get decandled from late May to late June. How decandling is done depends on the age, health, type, and state of progress of the tree as a bonsai. A good guide is seen on the blog, Bonsai Tonight; a thorough manual is available from Bonsai Today/Stone Lantern Press called PINES; and a fallback method is to cut them all at once in the second week of June. Cut them exactly straight across with very sharp scissors, leaving a green stub about as tall as the candle is thick. Never cut or remove weak interior buds because they may very likely be your valuable next branch to cut back to someday.
The weather in this region is notoriously changeable and unpredictable. Hot inland hills and colder ocean air push each other back and forth to create cold, then hot, mild, then strong breezes and winds, then give way to still, hot stretches. Trees slow or stop using or transpiring water when the temperature goes very much above 80° or so, and it’s easy to overwater and rot the roots. Wind can speed up water loss and leave you with wilt or burn or dying off. The rest of the time it’s perfect, man, just perfect. No better place to grow things than this.
So be watchful, and be careful. Be watchful in the garden and careful of the weather. Be watchful of your duties and careful of your relationships. Be watchful of the night sky and careful to use your days well. Be careful to use more of your heart than your eyes to watch over all, for all of your life.
– The Taskmaster