Indoor Bonsai - As Difficut As You Make It

 By Jack Wikle, Ann Arbor, Michigan

Introduction
Long ago I was taught that the gardener has a "fundamental choice" to make: either to grow only those plants adapted to his conditions and his care, or to modify his conditions and care to suit the plants he wants to grow. Either approach will work.

So, can bonsai be grown indoors? Certainly. You can do this if you really want to . . . probably more easily than you think. Visit the Fuku-bonsai.com website and read about David Fukumoto's "True Indoor Bonsai." These trees are almost foolproof plants adapted to long term survival with minimal care at very low light levels. Then, at the other extreme, re-read Jerry Meislik's account (this website) of how he grows banyans and other tropical species luxuriantly under high-output metal-halide lights. And, finally, read my fluorescent light bonsai recipe offered below for one more option. Of course, yet another possibility is to grow bonsai indoors keeping them close to a window in an effort to provide enough light. Weighing these options and keeping the fundamental choice in mind, it shouldn't be too difficult to settle on a level of involvement that will fit you and your circumstances.

Before going farther we need to make clear that growing bonsai is not doing lifeless models using sticks or clay. Bonsai are living trees or shrubs or, in some cases, even vines grown to look like trees. So, growing bonsai is partly horticulture, the nurturing of living plants. But, at its best, bonsai also involves artistic effort, the cultivation of trees as an aesthetic statement . . . as living sculpture. Certainly, the ongoing close involvement with living plants this implies is one of the great appeals of the bonsai hobby for many enthusiasts. Just be aware that most bonsai are not houseplants watered every week or so as the mood strikes and fertilized on whim. To paraphrase one of my old professors, who enjoyed tinkering with growing chrysanthemums as bonsai years ago, "Bonsai is not just watching plants grow, you get to do something with them."

So, if the thought of giving regular attention, like having a pet, and the need for a little bit of patience in finding out what will work for you is exciting rather than threatening, the rest doesn't have to be that difficult. Keep reading! It is amazing how much one can do in very limited space, with minimal equipment and no natural light.

Light
No natural light? Yes, no natural light. Okay, I need "grow lights" right? Wrong! You can use special grow lights but you don't have to. The great surprise to many people is that plants kept close to standard, home-and-office-type, cool white, fluorescent tubes grow reasonably well. A four foot long, two-tube, 40 watt, fluorescent fixture, supported in almost any convenient way is all you need to "get growing."

Purchasing an economical timer to turn the lights on and off while giving your trees 16 hours of light each day eliminates the hassle of remembering to do this on schedule.

Study the photos accompanying this article. The closer you can keep your trees to the fluorescent tubes the better they will grow.

Water
Next on our short list of absolute necessities is water. Don't make this more complicated than necessary. Experiment with water from your tap. If it carries a lot of dissolved minerals, think about what other water could be available to you. Do you have access to rain water, water discharged from a dehumidifier or an air conditioner, water de-mineralized by reverse osmosis equipment, or distilled water? If available, any of these can be expected to work better than hard tap water. However, if hard water from the tap is your only option, try adding a tablespoon or two of white vinegar per gallon to make your plants grow better. A word of caution, water "softened" by treatment with a water softener of the kind periodically recharged with salt is less likely to be satisfactory than any of the other possibilities mentioned (including vinegar treated water).

As a starting point, a misting bottle or a basting syringe will be adequate for applying water to the soil surface until it runs freely from the bonsai pot's drain hole(s). The flushing or leaching that takes place in liberal watering is important in preventing buildup in the soil of excess salts and other toxins.

Successful bonsai growers are usually attentive bonsai growers who check their bonsai daily and water thoroughly whenever the soil surface seems to be getting somewhat dry. Indoors, out of the sun and wind, it is very unlikely that waiting another day when in doubt will harm your tree. In most cases, the tree will be healthier if its soil is not kept constantly full of water . . . an alternating wetting and drying cycle works best.

Fertilizer
Yes, your indoor trees will need some fertilizer but not a lot. Contrary to our instincts, fertilizer will seldom save the weak and dying tree. More often it will be the stress that accelerates the tree's decline. Almost any water soluble "plant food" will work fine particularly if applied frequently in very light doses. Try a quarter of a teaspoon or less of fertilizer per gallon of water applied as a routine follow-up to each watering. It is best not to apply fertilizer solution to dry soil even at low concentrations. Water first then apply your fertilizer solution.

Soil
When only small quantities are needed, this can be one's biggest challenge. This statement about soil mix ingredients by soil scientists Handrek and Black (see footnote) seems right on target, "If you have a reasonable idea of what you are doing you can grow plants in almost anything. All you need to do is to adjust management practices to suit your mix. But if you know what you are doing you will choose components very carefully." Most bonsai growers agree that the goal is a very porous mix that holds water and allows air to enter at the same time. Unfortunately, they don't agree on the best way to achieve this.

Of course, purchasing packaged "bonsai soil" from a vendor is one way to go. (Ask who supplies soil to members of your local bonsai society or, easier perhaps, check the internet for sources.)

If you are compelled to mix your own soil, I am convinced you could do a lot worse than trying my "secret" recipe: 1 part (volume) Starter Chicken Grit (granite particles available wherever livestock feed is sold), 1 part sphagnum peat (break it up well and use particles that will pass through a five mesh (five openings per inch) screen, and 4 parts Turface (a commercial baked clay product widely used in "conditioning" athletic fields). No matter what components you choose, your mix will almost always be improved if each ingredient is shaken over a standard window screen (sixteen openings per inch) and anything that goes through the screen is discarded. Getting rid of the small particles that fill the spaces between the large particles opens the soil up letting excess water escape and air enter the mix very quickly after watering.

Air Temperature
Normal household air temperatures --- actually anything in the range from the low 60's to the low 80's Fahrenheit (15 to 27 degrees Celsius) should not be a problem. Most trees you might grow will also take higher or lower temperatures in stride. Just don't let the indoor bonsai freeze.

Plant Material
One more issue is to find plants adapted to the kind of controlled environment you develop when you choose to grow bonsai indoors relying on fluorescent lighting. Basically what you are seeking are warm climate plants, kinds not native where an extended cold dormant period is routine. This includes the broad range of woody plant material grown in the landscapes of southern United States in addition to subtropical and tropical species. And, of course, starting with a plant that has naturally small leaves and thin twigs makes pleasing proportions easier to achieve.

Any fig (Ficus species) is a candidate for growing as fluorescent light bonsai. Some other genera the author has found to be especially rewarding as small bonsai in the environment described here are: Buxus, Cotoneaster, Cuphea, Hedera (especially small-leaved cultivars), Myrtus, and Pyracantha. Actually, azaleas (genus Rhododendron) will also thrive and bloom several times a year under fluorescent lights operated sixteen hours a day.

For a more "evergreen" look, Chamaecyparis and Cupressus also grow well year around under cool white fluorescent light. And, in spite of the "common knowledge" that junipers cannot survive indoors with no outdoor vacations, I have two that have both grown relying solely on cool white fluorescent light --- on sixteen hours a day --- for more than twenty years.

As a source of plants hard to come by in other ways, consider making a propagating box that will fit comfortably under your fluorescent fixture. As one possibility, envision a gallon size, rectangular, antifreeze container trimmed to half its original depth except for its four corners which are retained to support a polyethylene bag that will cover the container. Most of the things I have been growing have been rooted successfully in this kind of box - with drain holes - almost touching the fluorescent tubes. A rooting mix of half sphagnum peat and half vermiculite has worked well for me. Half sphagnum peat and half perlite is also popular as a propagating medium. Make sure the rooting medium is thoroughly moistened, insert cuttings, cover rooting box with a gallon size "Baggie," set it under your fluorescent lights and wait. When roots have formed, pot the rooted cuttings into individual containers.

Getting Away
One more suggestion. Before leaving for a weekend or a week or two, water your mini-bonsai well, enclose each one in a transparent plastic bag and put them all back under the fluorescent fixture. When you return, open the bags for a half hour the first day home. Double the "out-time" the following day. Then continue this daily out-time doubling until they are out all day. I call this "programmed reentry." I do the same for freshly potted or repotted fluorescent light bonsai.

Remember
Light, water, fertilizer, soil, favorable temperatures and a plant. That's the "magic formula." Seems too simple doesn't it?

Footnote
Handreck & N. Black, 1984, Growing Media for Ornamental Plants & Turf.

Note
Jack Wikle has put together a thoughtful and valuable article on his techniques and thoughts on growing bonsai indoors under fluorescent lights. He is a bonsai teacher, demonstrator and lecturer and he has been creating marvelous bonsai for many years. Jack creates great outdoor bonsai but he is known throughout the bonsai community for his extensive experience growing tiny bonsai in his basement under simple fluorescent shop lights. I am also proud to acknowledge Jack as one of my bonsai teachers who has and continues to help me succeed with my bonsai.