by Jerry Meislik
This is a distillation of how I grow bonsai under lights. By way of introduction, I have been growing bonsai for over 30 years, and for most of those years I have grown indoor/tropical bonsai under varying conditions including windowsill, greenhouse, and artificial illumination.
While living in Michigan I started using metal halide lamps to help grow my indoor bonsai. Despite having the use of a greenhouse the addition of metal halide lights to supplement the natural light actually resulted in increase growth and vigor of my trees!
Since moving to Montana my new growing room is a conventional room with no skylights. Seven 1000 watt metal halide lights are hung from the ceiling. These lights and the windows provide the only light that my trees ever get. The plants never go outdoors even in summer, and must survive only on this light. At our location and 5000 foot elevation frost is possible any day of the year thus making the plants housebound.
The plant room floor is waterproof so careful watering is not required, and a centrally located floor drain removes the overflow. Plants are all arranged on food service carts on wheels. This allows the trees to be rotated, repositioned and household chores to be done with ease despite the huge size of some of the trees.
Visitors to the plant room are impressed with the health and vigorous growth that can be achieved with artificial illumination.
Light is critical
Under low light conditions most plants barely survive, and they do not grow enough to allow bonsai training. Compare the leaf density of two Ficus benjamina 'Kiki' that are the same age and were styled at the same time. One survives on a windowsill of one of my students and the other is growing under metal halide lamps.
Many species of trees will not survive indoors under typical home illumination and they gradually starve and die. The list of bonsai materials than can be grown indoors without supplemental light is very short. David Fukumoto has pioneered the selection and training of bonsai materials that can be grown under normal home illumination. See http://www.fukubonsai.com/ for further information on specific materials and techniques for success in typical home low light situations.
Jack Wikle of Michigan, one of my bonsai teachers, is a pioneer in growing bonsai under regular fluorescent light. Jack's indoor trees are grown under inexpensive fluorescent lights available at any hardware store and his results are marvelous. Many plant species grow beautifully under this type of supplemental illumination as Jack's trees demonstrate. See Jack's article by clicking here.
My friend Cyril Grum, Michigan, also uses inexpensive fluorescent lights to grow his small sized indoor bonsai. The trees are beautiful, healthy and his home-made light set up is fairlly easy to duplicate.
I have conducted experiments with Light Emitting Diode, LED, lights to see how they will compare to growing under fluorescent lights. Initial cost for LED lights is quite hight but the cost to run them is relatively inexpensive compared to metal halide lights. You can see the results of 3 sets of experiments done with LED lights here. Basically, not all LED lights are the equivalent of fluorescent lights although they may use less electric power.
Care Of Indoor Trees
All these plants grow, and their trunks thicken under the high light conditions and many will flower, and even set fruit!. Under low to moderate light these same materials merely survive without much growth.
Benefits of the metal halide lights
Metal halides can be found in 250 to 1000 Watt sizes. Each light comes with a transformer that can often can handle only one bulb, and only the bulb wattage for which it is built. So if you buy a 250 watt transformer you can not later upgrade it to a 1000 watt bulb for instance. Buy the size light that you will need, as upgrading to a higher wattage bulb is not possible.
Some light fixtures will allow switching form sodium to metal halide bulbs at different stages of the growth process to encourage blooms vs. vegetative growth.
Using metal halide bulbs you can grow many high light materials. These plants will actually grow significantly and increase their girth and leaf density. Under moderate to low light situations these plants will be almost static and not show any real increase in their size or ramification.
Disadvantages of metal halide lights
In addition each bulb has a transformer that makes an annoying humming sound. One transformer is required for each bulb. Transformer noise can be troublesome in a quiet home situation. My transformers are all located in a room below the plant room for this reason.
The bulbs and the transformer must not get wet. In addition a wet bulb may shatter so keep any moisture off the bulbs as well as the transformer box.
Bulbs lose their efficiency over a one to two year period and will need to be replaced, and they are somewhat costly to purchase. In addition, some of the transformer components burned out and I have had to replace them as well.
All Rights Reserved © 2011 Jerry Meislik