Bonsai is the Japanese art of growing beautiful trees in miniature. Almost any kind of tree or plant can be a Bonsai, with the right care and styling techniques. The important thing to remember is that a Bonsai is a tree, and has a tree’s needs. Trees respond to your care, and will thrive with your attention!
Bonsai need direct sunlight, from which they make their food. A lack of direct sun will damage them, causing weak foliage and other problems. They like to receive 5-6 hours of sunlight daily, whether inside or outside. All Bonsai love to be outside in the warmer months (May-September), though there are many species which can be kept indoors year-round. Remember that the more sunlight and warmth your Bonsai receives, the more often it will need water.
Proper watering is essential to the health of your tree. Bonsai like to get a little dry in between waterings, but they must never be allowed to become bone-dry. Check your Bonsai daily to see if it needs water by pressing down firmly on the moss or soil at the base of the trunk. If it feels moist or cool, or sort of soft and spongy, then it does not need water. When the topsoil feels dry, set the whole pot in a basin of water, right up to the base of the trunk, allowing water to saturate the soil. This will cause air bubbles to rise up, and the bubbles are a good indicator of how dry your tree is. The soil will be saturated very quickly; let extra water drain off. Bonsai really don’t like to be wet all the time, nor to sit in water for long periods, it is bad for their health. During the winter months, you may be watering once a week, or even less; in the summer, it may every day or every other day, depending on location and climate. The cycle will vary, so avoid strict schedules and you will soon recognize the watering needs of your Bonsai.
Misting and air:
Any time your tree is inside, the air is very dry, and the leaves want humidity to keep them healthy and green. Mist as often as you like during the day. Definitely avoid having your Bonsai near a vent or a draft, as this will dry out the foliage. Using a pebble tray is a great way to increase local humidity. A pebble tray is a shallow tray filled with small stones. Keep some water in the bottom of the tray, making sure that the water does not reach the bottom of the Bonsai pot. As it evaporates, it helps to create a more moist environment.
Fertilizer is not quite food for plants, it is more like vitamins and minerals. As with vitamins, a small amount on a regular basis is the best plan. Most Bonsai should be mildly fertilized once or twice per month. You can use our specially formulated bonsai fertilizer, such as Green Dragon, or any houseplant fertilizer such as Peter’s or Miracle-Gro at half the suggested strength. Always water your tree before fertilizing. Warning: do not fertilize weak or freshly repotted trees, and don’t over-fertilize! This may burn the roots and cause stress to the tree.
Most trees have a natural resistance to insects especially when grown under healthy outdoor summer conditions. However we recommend using commonly available garden insecticides or organic sprays several times per year as a preventative measure. Learn your insects and diseases to minimize the amount of spraying and to target the correct problems.
At Bonsai West, we have found it useful to group trees into two general care categories: Indoor/Tropical and Outdoor/Cold Hardy Bonsai. These two broad categories are based on the trees natural habitat and determined by its growing zone. Cold hardy trees should not be grown in the house, as they need to go dormant for the winter, and conversely tropical trees should never be allowed to freeze.
Following are some general rules and guidelines for Bonsai care with these categories in mind.
Indoor or Tropical Bonsai are trees which normally grow in the deep south or in tropical climates. These trees are cold-sensitive, and should not be allowed temperatures below 45 degrees F. They do not like extremely dry or arid conditions, and they want lots of sun. Tropical Bonsai may be kept on a sunny windowsill year-round. During the summer they love to be outside, but they will also do well indoors. The air inside the house is very dry, so the use of a pebble tray or frequent misting is important. Tropical Bonsai like to be fertilized during the growing season. They will need pruning 3-4 times per year, and root pruning or repotting every 2-3 years in the spring or summer.
Bonsai in this group include Mini Jade, Arboracola, Tropical Cherry, Bougainvillea, Figs, Olives, Natal Plum, Palms, Gardenia, Brazilian Raintree, Jaboticaba, Podocarpus, Powder puff, Pomegranate, Texas Ebony, and Buttonwood.
Cold Hardy Bonsai are varieties which need a full change of season to do well. These trees cannot be grown as indoor Bonsai! From May through mid-November, keep your cold-hardy Bonsai outside, in a fairly sunny spot. Gradually decreasing temperatures will put your tree into dormancy, slowing growth and storing energy for spring. When it becomes too cold for your Bonsai to stay outdoors, move it to a protected but unheated area. Some options are a cold-frame, a garage, and enclosed porch, or a bulkhead. Be careful to avoid temperatures below 20 degrees. If you suspect that your winter location will get too cold, you will need to build more protection such as an insulated box or add additional heat.
Your Bonsai can be frozen for a few days during the winter, but not for extended time. Water your dormant bonsai as needed, keeping an eye on the temperatures: every 3-6 weeks, there is usually a thaw, and your tree might need water at that point.
Some trees may begin to break dormancy early: begin checking on your tree in February for signs of budding. When your tree is at 40 degrees or colder, it does not need sunlight, it is fully dormant. When temperatures begin to increase, the tree will begin to wake and grow. If your tree breaks dormancy, you need to give it light: move it into the coolest possible place where it still receives some sunlight. Your Bonsai now will be needing more water, and protection from freezes. Sudden freezes can damage new growth. By the end of April, the temperatures will have become warm enough to place your Bonsai outside again.
Cold Hardy varieties include Juniper, Pine, Spruce, Hinoki Cypress, Cryptomeria, Hemlock, Azalea, Cedar, Maple, Chinese Elm, Larch, Hornbeam, Beech, Wisteria, and Redwood.