Hardy bonsai include all varieties that naturally occur in temperate regions of the world. Therefore, these trees require four
distinct seasons including a cold winter dormancy. Hardy bonsai include Juniper, Pine, Larch, Maple, Hornbeam and others. These are generally not suited for growing indoors.
Proper watering is critical! Feel the surface of the soil daily. If the surface is dry or only slightly moist it is time to water. Water from above and thoroughly soak the soil. Watering
the foliage as well as the soil is also beneficial for your tree. Allow excess water to drain away quickly and never let your
tree sit in water for extended periods. During hot dry weather or under windy conditions your tree will need frequent watering. Very small bonsai in small pots can sometimes dry out in a day or less. Most do not like their soil to become really dry. Consistent bone-dry conditions are likely to kill your tree.
Conifers such as junipers, pines and spruces thrive in direct sunlight
and can gradually be acclimated to full sun. Deciduous trees such as maples and elms need to be grown in very bright light to
part sun. Hot sun and wind can cause leaf burn, so you may need to provide some protection from hot midday sun. Very small
bonsai in small pots do better in some shade.
Hardy bonsai need a cold winter dormancy to grow well. Once temperatures
are consistently above freezing in spring, your bonsai should be placed outside and allowed to remain there all spring, summer, and
fall. Once night temperatures drop below 35 degrees your tree will need some winter protection from the cold and wind. An unheated garage, basement, cold frame or a very, very cool room in the house are all suitable locations. Bonsai that drop their
leaves can be placed in the dark. Even though dormant trees use much less water, completely drying out can still be dangerous
so remember to check regularly for water.
Hardy bonsai do best with frequent feeding during the growing season (spring, summer
and fall). Organic feeding can be done with Green King pellets. Miracle-gro or Schultz water soluble fertilizers can be
used but should be mixed only half as strong as the directions recommend. The idea is to keep your tree healthy and maintain
very moderate growth. Do not feed in the winter.
Most bonsai need to be repotted and/or root pruned every 2 to 3 years. It is best done in the spring once your tree has started growing well again. Normally a quarter to half of the root mass is
removed to allow for fresh soil and new roots to grow which will reinvigorate your tree. Occasional trimming and wiring will
also be necessary to maintain form. A good book or bonsai professional might be a good consultant.