With the arrival of summer most of the formal bonsai shows have passed and the bonsaiist has the pleasure of displaying their own trees. The objective of a good hobbyist is pride in the finished tree. This can be achieved by maintaining its good health, continuing a selective feeding routine and paying attention to weather conditions which set the guidelines for proper watering requirements. Summer maintenance will prepare the trees for fall and winter planning ahead.
Start with the constant surveillance of fast summer growth. Warm days, and cool nights encourage the development of new tip growth, long internodes and lush foliage. Maintenance must include pinching and plucking of the growing tips as well as cutting back the branches. Reducing the branch extensions will encourage shorter internodes, tighter evergreen formations and develop desirable twiggyness on deciduous trees. Keep trimming and shaping unwanted growth to maintain form and design.
A regular program of feeding during the summer months is important. Reduction of the nitrogen content of the fertilizer mix will inhibit excessive green growth and allow for the formation of chemical changes which will produce the best fall colors. The basic mix of cottonseed meal (70%) and bone meal (30 %) can be altered to increase the bone meal, thereby providing more potassium and phosphorus to harden the woody growth and induce the development of fruit and flower buds for next year. Do not feed plants which appear to be suffering from summer stress due to oppressive heat or moisture deprivation.
Watering is most important during the summer months. Don't overlook the obvious drying extremes in a shallow bonsai pot. Root systems are stressed, and moisture containment is a must. Neglect will cause twig die-back, leaf drop, and leaf droop. Summer stress will weaken a tree and threaten its future health. Water more frequently with shorter soaking periods. Be sure your soil mix contains some humus to retain the moisture as well as an aggregate (i.e. pumice, sand, d.g. or lava rock) to encourage good drainage. Early morning watering will allow foliage to dry during the day. Early watering will inhibit and prevent the formation and growth of harmful fungus. While watering your trees, briskly spray the tree's foliage to remove impurities and discourage red spider mites, ants, and other insects. Be sure the water penetrates the root ball. Remove any excess patches of moss or build-up of thatch which will repel water. Check the soil levels around the rim of the pot. Provide a ridge to encourage the water to drain into the pot rather than over the rim. Keep checking any automatic watering systems. You may be relying on to be sure they are functioning properly. Have a bonsai friend keep an eye on this activity if you are vacationing.
Late June and into mid-July is the period for leaf pruning. If done any later ,the summer heat may immediately destroy the young new secondary growth. Feed the deciduous tree well before you proceed. Check the base of the older leaves to ascertain the presence of tine new leaf buds which will provide a second spring. Do not defoliate a tree which has not yetformed these buds. While most varieties of deciduous trees benefit from occasional leaf pruning, do not stress the tree by doing it each year. Protect the "naked tree" from strong sunshine until the new leaflets have formed and hardened. Minimize your watering activities on these trees during this early stage since there is no foliage to allow for expiration of moisture from the root system.
With the beginning of summer, most transplanting must be curtailed. Some material such as pomegranates, tropical ficus, cotoneaster, bamboo, palms, wisteria, and pyracantha can be repotted during the warmer months. However, do not allow the fine feeding roots to be exposed to drying air. A good technique is to mist the roots and dust them with a fine soil mix, as a coating. This will protect them during the repotting process. Warm sunny weather stimulates root growth and will help the trees to become reestablished. Don't overlook watering!
Now, the last important seasonal suggestion -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 - Benelate«, Kelthane«, Captan«, Subdue« and Bravo«. Each is designed to do its own thing. READ THE PRODUCT LABELS CAREFULLY.
Plan ahead. The wonderful colors and foliage textures of fall are not too far away!