Seasonal Care

Bonsai from miniature forest trees must live outdoors all the time.They are brought into the house for short periods on specialoccasions. Bonsai from forest trees will die if kept too long indoors,particularly in overheated rooms. These bonsai may be brought insideonce or twice a week for 2 or 3 hours -- during winter, spring, andautumn. They should not be brought inside in summer unless the room iswell ventilated.

Summer care

Bonsai are very sensitive and thrive best in localities that offer coolnights, sunny days, and mist or rain almost daily. Most of the UnitedStates does not have this climate, so special provisions must be madeto compensate for the lack of desired climatic conditions. Extremes inlight, rain, and wind are to be avoided.

Place your bonsai on a platform or table in your garden where theplants can receive 3 to 5 hours of direct sunlight a day. The siteshould be shaded, preferably in the afternoon. If the area is subjectto drying winds, put up screening around the plants to protect them.Screening also serves to provide the plants with shade.

Water the entire bonsai -- plant and soil -- daily. If you skip even 1day you can permanently damage the plant. Make sure your plants arelocated where rain can fall on them. However, plants should not remainwet or water-logged for long periods.


To maintain plant growth use fertilizer to supply nutrients. Maintainthe nutrient level in the soil mix throughout active growth withmonthly applications of a diluted liquid fertilizer. Apply fertilizeronly before and during active growth. For a liquid fertilizer you canuse a typical house-plant fertilizer (20-20-20 or its equivalent) diluted to one-quarter strength on the label. For more information on Summer Bonsai care, read our Summer Care for Bonsai page.

Fall care

During this period bonsai must be prepared to endure the approachingcold. Plant growth must be slowed. Water plants less frequently to slowgrowth, and, when growth slows, reduce applications of fertilizers.

Do not prune or cut any branches after mid-August. Do not useartificial night-lighting (incandescent filament lamps) on plants afterAugust 1. To reduce winter dieback of flowering trees and maples makelight applications of 0-10-10 fertilizer. Formore information on Winter Bonsai care, read our Fall Care for Bonsai page.

Winter care

A major problem in winter is to protect bonsai against low temperaturesand drying winds. Bonsai can only be left outdoors in climates wheretemperatures drop no lower than 28 F degrees. This is not the casethroughout most of the United States, so a greenhouse, pit, orcoldframe is necessary.

Winter frosts will seldom bother bonsai that are sheltered under thefoliage of a spreading tree. Watch out, however, during the frostperiod for drying soil.


It is easy to construct a simple coldframe for bonsai. Before theground is frozen, dig a hole at least 1-1/2 feet in the soil. Make thehole as long and as wide as you need for all your plants. Line thesides of this hole with exterior grade plywood which extends 6 inchesabove the surface. Put 4 to 6 inches of gravel in the bottom of thehole, set your plant containers on this gravel, and spread straw aroundand over them. Put a loose-fitting cover on the frame made ofpolyethylene sheeting or any similar material.

Be sure the top of your coldframe is strong enough to withstand a heavyload of snow. Ventilate on days when the air temperature is above 40 Fdegrees to keep the plants cool and dormant.

To purchase a coldframe kit, check your local nurseries or see catalogsof mail-order garden supply houses. For more information on Winter Bonsai care, read our Winter Care for Bonsai page.

Spring care

Spring is the time when new bonsai are started. It is the time for anypruning and training of last season's bonsai. The plants then have awhole growing season to readjust to these changes.


In the summer, during hot weather when the temperature is over 90 Fdegrees, water the bonsai plants one or more times a day. If the plantsare in an unusually sandy soil they will require watering three or moretimes a day.

In early autumn, follow the watering directions for late spring. Inlate autumn, follow the watering directions for early spring.

In winter, keep the trees in a coldframe and ventilate the plants onone or more sides to keep them dormant. Check for dryness every 2weeks. Water the plants every second day, or less, as required. Keepin mind that far more bonsai are killed by overwatering than by a lackof water. For more information on Spring Bonsai care, read our Spring Care for Bonsai page.

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