SUMMER SURVEILLANCE—SLOW GROWTH, MORE CARE by Marty Mann

Since most plant growth slows down during the warm summer months, diligent attention must be given to its needs. Excessive water or improper feeding can do more harm than good. Trees must be protected from summer heat and dehydrating winds. Trees requiring special care should be grouped together to simplify attention. It’s important to keep the pots and root systems cool.

A regular feeding program during the summer months is essential. Reduction of the nitrogen content of the fertilizer mix inhibits excessive green growth and allows for the formation of chemical changes that produce the best fall color of your deciduous trees.

Feed sparingly during hot summer months. Use a half-strength liquid or a granular fertilizer (0-10-10) to provide an excellent source of phosphorus and potassium. Regular feeding during the hot summer months may be supplemented by early morning refreshing foliar feeding of Miracle-Gro. Use Miracid to correct the PH condition for acid-loving plants. {Kathy Shaner and Kusamura recommend Whitney Farms 5-5-5 and not Miracle-Gro.}

However, yellowing or leaf-drop indicates a need for more nitrogen or iron. It also suggests over watering, poor drainage or insect damage.

The basic mix of cottonseed meal (70%) and bone meal (30 %) can be altered. Increasing the bone meal provides more potassium and phosphorus to harden the woody growth and improve the rootage. These changes induce the development of fruit and flower buds for next year. Do not feed plants that appear to be suffering from summer stress due to oppressive heat or moisture deprivation.

Late June or early July is still time to consider leaf pruning. Be certain to work with healthy trees only. The removal of large and sunburned leaves enhances the look of the tree. It’s often natural for moss on the surface of plantings to become brown at this time due to the heat. If the moss color remains green, it may indicate an excess of water or a poor draining soil mixture. Water early in the day or in the late afternoon. Be sure the leaves have time to dry before nighttime. Moisture on the leaves encourages the formation of fungus growth.

As soil temperatures increase during summer months, the root system growth slows down considerably. Conversely, the top growth of most species will be vigorous. Overall, growth requires a careful selection of areas requiring pruning and general shaping. Do not forget your overall design objectives.

Azaleas now require special care and attention. They have just finished blooming. The current year's crop of new shoots must be cut after the flowers begin to fade and lose vigor. General con­structive overall trimming is also done at this time. Remove the spent flowers and all shoots that have grown upward or downward. Trim back to at least two or three leaf sets on each shoot. Allow new buds to form and new branch divisions to occur. Don’t cut back to bare wood at this time of year. Azaleas generally bud back on bare branches better in the spring. Summer cutting risks branch die back. Branches may be carefully wired to establish form and style. You risk losing the plant's ability to form new flower buds for a show of color next spring if the trimming is done after July. Watch the wire. As the leaves mature, growth slows. The tree continues to lignify and build woody portions to its branches and trunk. Wire gets hot in the summer sun and severe damage to the tender bark will occur.

Check plants for long internodes or too much growth in the dominant upper areas. Continue pinching and trimming. Pruning is essential for balance and retention of style. Eliminate defects such as parallel branches, crossing branches and improperly positioned limbs. Continue pinching the weaker twigs from three branch forks. Keep promoting the growth that creates compact foliage mass. This work can be done at any time up to fall dormancy.

With the heat and the long days of summer you may think you can slow down the constant training and just sit back to enjoy the trees. Doing less, yes. Sit back? Not a chance. Now is the time to follow up on all the care and design you have been working on since spring brought the trees back to life.

California has certainly had its share of deep rain. Rain, coupled with a continuous program of feeding, caused plants to grow vigorously. Trees with large amounts of foliage may need to be moved out of full sun into shaded or partially shaded areas to protect leaf surfaces and fine surface rootage. Keep rotating all full-grown material on a regular basis to expose them to even light conditions. Maintain high humidity and good air circulation. These activities protect the bonsai as well as improving the maturing fall colors.

This is not the best time to consider transplanting most material. However, certain plants such as Pomegranate, Ficus, Buttonwood, Cotoneaster, Pyracantha and most Bamboos can be repotted or trans­planted during the warm weather. Material that had recently been defoliated, such as Maple, Olive, Privet, Zelkova, and Ginkgo can be transplanted just prior to the re-emergence of the new growth. Remember that transplanting of any material during these warm months is risky but it can be done if proper after-care is taken. Keep them cool and not too wet. Generally speaking, anything done during the summer months should be done with restraint and proper attention given to the effect of warm weather.

Propagation by cuttings of softwood or semi-hardwood material can be done in July. Keep cuttings in shade and in a sandy, moist mixture. Don't rush to transplant any cuttings just because the new signs of growth tell you that they have 'taken'. Let them harden-off first.

This is a period of extraordinary activity for garden pests. The warm air and frequent watering encourages aphids, scale, mealy bugs, red spider mites, and, fungus—both above and below ground level. Keep at them all with insecticides—Malathion®, Isotox®, Sevin®, and fungicides—Kelthane®, Captan®, Subdue® and Bravo®. Each is designed to do its own thing.

Marty Mann is the author of BONSAI IDEAS a recently issued compendium of informative articles. 

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