Introduction.Growing bonsai indoors is one of the passions that has kept me enthralled with bonsai for nearly 30 years. During that time I have grown bonsai on windowsills and indoors under various types of artificial light. Over the years I have learned some crucial concepts about growing trees indoors. This article will present some of these ideas that may help you save time, effort and avoid killing trees in your indoor growing efforts.
Indoors is not indoors.
At best growing trees indoors is a difficult task, and part of the problem is that indoor growing conditions are not at all similar to the natural conditions under which trees normally grow. The climate in your home is quite variable. Homes are too dimly lit, too dry and lack good air movement. One window in your home may drop to 48 degrees Fahrenheit at night, while another windowsill may rise to over 100 degrees on a sunny day! One spot in the living room is extremely dark with almost no light and another area has intensely bright southwest light streaming in from the window. Trees that grow well in one room may not thrive in another room in the same house. Finding the right microclimate in a home is a huge part of winning the battle.
A very cool room or basement is the ideal place to grow boxwood, Crape Myrtle, Cotoneaster, Chamaecyparis, Serissa, and citrus, while a warmer room is the best place for Ficus, Schefflera, Wrightia religiosa, and buttonwood. Ask friends who are successful in growing trees indoors about the lighting, humidity, temperature range, soil, and water conditions that work for them. Use these suggestions as a starting point for your indoor growing and modify these conditions to suit the types of trees that you grow.
All plants are not created equal.
Most trees will NOT survive indoors for long periods of time, while a few trees are proven indoor survivors. One key element to successfully growing bonsai indoors is selecting trees that will survive indoors. Temperate trees, those requiring a cool dormancy period, such as maples, larch, pines, and junipers will usually not live for long in your home. Tropical and sub-tropical trees such as Ficus, Brassaia/Schefflera, Sageretia, and Portulacaria are quite happy in most homes and will not require a winter rest and chilling period. They also will not have leaf drop and sit in leafless condition for weeks while waiting for the start of their spring growth period.
One way to find suitable trees that may work for your indoor situation is to go to the produce section of your supermarket and buy some fruit; try guava, lemon, kumquat, and tamarind. As you eat the fruits, save the seeds and plant them. Some of these will survive and may make reasonable plants for indoor bonsai. Next, go to your local plant nursery and select any small-leaved tree from their terrarium selection. Trees that you can find are Ficus, Schefflera, Cotoneaster, Chamaecyparis, boxwood, myrtle, elm, and ivy. Select cultivars with small waxy leaves, compact growth and short internodes. Avoid plants with long stems, long leaves and long petioles.
Grow these plants in your home, and over a year or two some will survive while others will die. Select the healthy and growing survivors and concentrate your efforts on these few varieties of trees. Propagate the vigorous trees and discard the weak trees. Make sure to have at least three or four specimens of each of the strong varieties. Propagate the survivors from cuttings to have more specimens to work with and to share with friends.
After you have experience growing trees and keeping them alive in your home, purchase some pre-bonsai and finished indoor bonsai from a reputable bonsai nursery. Ask specifically if these plants can be grown indoors or whether they will require a dormant period or an outdoor summer growth period. These more developed trees can be admired immediately, while your young, new experimental trees will take time to mature into respectable bonsai.
Light and more light.
Growing trees in a dark corner of an apartment is doomed to failure. Over the last eight years, I have become convinced that the most critical element to long term success with indoor bonsai is strong, bright light. Given enough light many trees will grow indoors and become wonderful bonsai. In dim indoor light almost no trees will survive.
In most homes windowsill growing is at best a borderline solution, as window light is often dim and unreliable. For most indoor growers, supplemental artificial light is the only way to go, and my recommendation for anyone with a small bonsai collection is to use POF, plain old fluorescent lights. POF are inexpensive to purchase and to run. At the local hardware store purchase four foot long fluorescent fixtures. Use simple chains to hang these over the bonsai growing area. Or use one of the compact fluorescent bulbs if you only have one or two small bonsai.
Do not bother to search for special plant bulbs. The normal daylight or warm white spectrum bulbs work just fine and they are much less expensive. The key is to have the plant’s leaves nearly touching the bulbs. Fluorescent lights are relatively weak in light energy and they must be left on for at least 16 to 18 hours each day. A simple electric timer will cycle the lights on and off automatically. You do not need to create seasonal daylength light changes for most trees.
Other types of lighting include incandescent bulbs, metal halides, halogen and LED’s. All of these have some major disadvantages and all of these except the LED’s get quite hot and can burn the leaves if too close to the plant. Whatever lighting you use the key factor is to increase the amount of light available to the trees. Trees in dark areas literally are starving to death.
I encourage those who have tried to grow trees indoors and failed, to try again with supplemental lighting.
Temperate trees need special care.
Most tropical trees will be happy year round in the normal temperature range of a typical home, 60-90 degrees Fahrenheit. However, if you are trying to grow other than tropical trees, you likely will experience great difficulty unless you allow these trees to slow their growth down in the fall. Trees such as Cotoneaster, holly, elm, boxwood, pomegranate, Serissa, and azalea can be grown indoors, but many successful growers of these plants grow them in much cooler temperatures than exist in most homes.
To succeed with these plants try a cool basement, or a really cool window in an unheated, spare bedroom. Temperatures of 40-50F may permit some success with these species. Besides cooling down the growing area, another trick for success with these trees is to raise the humidity level. A humidifier can be placed near the plants or the plants can be surrounded with a plastic tent to increase the humidity. Leave the top of the tent open to keep fungal problems from developing. Cooler temperatures also help by keeping the relative humidity higher. Another technique to keep the humidity level up is to keep trays full of water near the trees but never allow the trees to sit in this water.
The last suggestion is to allow the soil of these temperate trees to become definitely drier during their winter rest period; inactive trees need less water. Begin watering them normally when they resume active growth.
Soil, Water, Humidity, Fertilizer.
Purchase bonsai soil from a reputable dealer. Bonsai soil should be a particulate mix of ingredients with soil particles mainly 2-3 mm in size. You can mix your own soil at much less cost but the ins and outs of how to do this are beyond the scope of this introductory article.
Watering your bonsai is a complex subject with many variables. My best suggestion to you is to water your trees thoroughly from above allowing the water to soak into and through the soil until the soil is completely wet and water is coming out of the drainage hole. By the way, all pots must have at least one drain hole. Do not water again until the soil is nearly dry to about 1 inch below the surface. The ideal time period for this to occur is 24-36 hours. If your soil is staying wet for longer than this time interval your soil is too water retentive and you will lose some trees due to root rot.
Tap water in most municipalities is acceptable for most bonsai. If chorine is used in your water allow the water to sit for 24 hours before using it on plants. This will also allow the water to warm up to room temperature as well as time for the chlorine to dissipate. If your local water is too mineral laden you may need to collect rainwater, water from a dehumidifier, air conditioner or from a reverse osmosis unit.
If your bonsai was purchased with glued-on-rocks on its surface these must be removed. They will prevent you from accurately gauging the soil moisture. Use a screwdriver to pry off the rocks and discard them and then top off the pot with fresh bonsai soil.
Misting is a nice tool to refresh your trees, clean accumulated dust off the leaves, and to increase the humidity level but it does not replace watering thoroughly and properly. Under many growing conditions misting can promote fungal attacks on leaves and stems.
Room humidity is too low in most homes. Use a small room humidifier close to your plants to raise the humidity level. Your bonsai will appreciate this extra effort.
Fertilize actively growing trees every two weeks with a houseplant liquid fertilizer mixed at half the recommended strength. If directions call for two tablespoons per gallon, then use one tablespoon per gallon. Make sure that the plant is watered well before you fertilize. Do not ever fertilize your tree if it is sick, not growing or recently repotted. That is a sure way to damage or kill your tree.
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One essential fire to successfully growing bonsai indoors is choosing elders that mind endure indoors. Cool shrubs, those requiring a remote dormancy epoch, such as maples, larch, mopes, besides junipers determination normally negative animated for tedious in your house...best dehumidifier
ReplyDeleteDo you have a recommendation of soil that you use that is not very water retentive? I have had trouble with rotting bonsai in the past. Thanks... Bonsai Care
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