By Jerry Meislik  (Whitefish, Montana)
Meislik light 1a.jpg (50517 bytes)         I've been growing bonsai for over 26 years, and for most of those years I've grown indoor and tropical bonsai under varying conditions including windowsill, greenhouse, and artificial illumination. While living in Michigan I started using metal halide lamps. The addition of metal halide lights to supplement the natural greenhouse light resulted in increase growth and vigor of my trees!

        My new Montana growing room has no skylights. Nine 1,000 watt metal halide lights are hung from the ceiling to supplement the natural window light. The plants NEVER go outdoors, even in summer, and must survive only on this light. At our location at a  5,000 foot elevation, frost is possible any day of the year. This makes the plants housebound.

        The plant room floor is waterproof so careful watering is not required. A centrally located floor drain removes the overflow. Plants are all arranged on wheeled food service carts. 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. I'm happy to summarize and share my high-light experiences and conditions with the bonsai community.

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        The number one factor in growing plants is water, since plants will survive only one week without it. Light is the second most important factor and it is the "food" supply for your plants. Green chlorophyll in the leaf and stems transforms light energy, water, carbon dioxide, and minerals into sugars and everything else a plant needs to survive.

      Left photo: Jerry's plant room with metal halide lights suspended from the ceiling with waterproof floor, and plant carts.

Meislik light 3a.jpg (10378 bytes)  Meislik light 4a.jpg (13760 bytes)         Under low light conditions most plants barely survive, and they do not grow enough to allow bonsai training. Simply compare the leaf density of two Ficus benjamina cv. 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.

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       The left photo shows a  very healthy Chinese Banyan  (Ficus retusa)  grown for the last two years under my metal halide lights. It would be impossible to get such healthy growth in ordinary indoor conditions! Most trees will not survive indoors under typical home illumination and they gradually starve and die.

        Jack Wikle of Michigan, one of my bonsai teachers, is a pioneer of growing bonsai under regular inexpensive fluorescent lights available at any hardware store.  Jack grows many plant species under fluorescent supplemental illumination and his results are marvelous!  (FBnews editor note:  An article by Jack Wikle also appears in this issue.  Go to )

        David Fukumoto of Fuku-Bonsai (Hawaii) has pioneered the selection and training of bonsai materials that can be grown under normal home or office lighting. The list of bonsai materials than can be grown indoors without supplemental light is very short.

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        WATER.  My trees are watered once a day with reverse osmosis water. This is water that has no salts, or minerals in it, and is the equivalent of distilled or rain water. As long as your tap water is not too mineral laden it should do well for your indoor trees.

        SOIL MEDIA. I use red lava crushed to about 1/8 inch size either as 100% of my soil mix or amended with an equal volume of small bark chips. Most of my indoor trees do not seem to prefer one mix or the other. Re-potting is done every two to three years for most trees.

       The left photo is Ficus retusa that had been recently leaf pruned. The original stock was purchased from Fuku-Bonsai 18 years ago.

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         I have had this third Ficus retusa for 13 years and have grown it under metal halide lights for the last 3 years.

        FERTILIZATION.   With a mostly inorganic mix, fertilization is important. I fertilize every week with varying brands of half-strength houseplant fertilizer used only after thoroughly watering the trees. I do not fertilize trees that have been newly repotted or those growing weakly and I don't fertilize during slow-growth seasons.



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        DISEASE.   Insects and diseases can be a real problem in the confined spaces of a growing room or greenhouse. Bugs usually enter the plant room on newly bought trees, therefore I isolate all new trees for two weeks and spray them with insecticide several times before they are permitted into the plant room. Typical problems include white fly, scale, mites and mealy bugs. The usual sprays are used to control the problems. Keeping room air circulating with fans also helps to discourage many insects.

       TEMPERATURE.   The temperature range in the plant room is 65 to 95 Fahrenheit, and this seems to be reasonable for most trees.

        HUMIDITY   It stays fairly humid and I don't try to control humidity in the plant room. I find that most trees are not particular. Plants with thin leaves dry out in extremely low humidity while those with thick, waxy leaves tolerate dry air best.

        At left is a Water Jasmine (Wrightia religiosa) imported from Malaysia 10 years ago.

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       PLANTS. I've successfully grown indoors under metal halide lights:  Ficus, Wrightia religiosa, Baeckia frutescens, Buttonwood, Casuarina equisetifolia, Diospyros, Caesalpina ferrea, Portulacaria afra, Coccoloba uvifera, Nea buxifolia, Fortunella hindsii, Bougainvillea glabra, Brassaia actinophylla, Carissa grandiflora, Hibiscus rosa sinensis, Psidium littorale, Phyllanthus sinensis, Sageretia theezans, Schefflera arboricola, and Tamarindus indica.

        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.

        Casuarina equisetifolia, a high-light tree, and outside the window 4 feet of snow!

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        BENEFITS.  Metal halide lights provide high light output at relatively high efficiency levels. The lights come in many sizes, shape and types. One type of metal halide bulb is sodium. Sodium lamps are yellow in color and give the plants a peculiar appearance. The sodium bulbs also allow stem elongation, or etiolation which is not desirable in bonsai.  The photo shows a close up of the metal halide bulb and housing.

        Metal halides can be found in 250 to 1000 Watt sizes. Each light comes with a transformer that 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.

       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.

Meislik light 11a.jpg (90726 bytes)         DISADVANTAGES.   These lights produce significant heat from the bulbs. This means that the tops of the trees can not be closer than one foot from the bulbs or the nearest leaves will burn!
Meislik 12a.jpg (80663 bytes)         Each bulb requires a separate transformer that makes an annoying humming sound. Transformer noise can be troublesome in a quiet home so all of my transformers were placed in the room below the plant room. The bulbs and the transformer must not get wet. 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. They are somewhat costly to purchase. In addition, some of the transformer components burned out and I have had to replace them as well.


        Light supplementation of any sort is advisable for the best growth and survival of indoor bonsai. For those who cannot supplement their indoor lighting the use of low light trees is necessary. Supplementation with fluorescent light allows more plant varieties to be grown, while metal halide lights allow growing high-light requiring plants. For those who want to grow "finicky" tropicals, I strongly suggest using metal halide light supplementation!


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        Jerry is an enthusiastic hobbyist and the most knowledgeable about growing high-light tropical bonsai in cooler climates. Now retired and looking to share his knowledge, he's available for bonsai teaching tours.  He has a lot to share!

        While living in Michigan he held many positions at the Ann Arbor Bonsai Society and is currently vice-president of the Big Sky Bonsai Society in Montana. He's been a director of the American Bonsai Society, Chair of the American Bonsai Society Editorial Board, and board member of the National Bonsai Foundation.

        He teaches bonsai at Flathead Valley Community College and throughout the country. He travels extensively and shares his knowledge and experiences in The Bonsai Enthusiast - Online Journal,  American Bonsai Society Journal, International Bonsai, and the Bonsai Clubs International's Bonsai Magazine.

                The above article and photographs are copyrighted 2002 by Jerry Meislik and used by permission. In addition, Jerry is the Northwest Regional Editor of the North America Bonsai Federation and a Fuku-Bonsai stockholder.

                Jerry has proven the basic rules for success:  Select trees that will grow well for you in your environment, OR CHANGE YOUR ENVIRONMENT TO CREATE OPTIMUM GROWTH!  He also tries to acquire the best quality stock and, in giving skilled training to each tree, his trees are outstanding! 

                 The bonsai community is very fortunate that there are individuals like Jerry. Please visit his website:  and contact him for more details.  If you set up similar equipment, keep me posted as high-light equipment will greatly improve even Fuku-Bonsai's TRUE INDOOR BONSAI™!

                Jerry and I will be conducting controlled comparative experiments that we'll be sharing with the bonsai community.     ~~~David W. Fukumoto


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