FEBRUARY 2013 topics:
                         GROWING ENVIRONMENTS
                         DO PLANTS GROW THROUGHOUT THE YEAR?
                         WHAT IS THE BEST TIME FOR REPOTTING?

By Jerry "Bonsaihunk" Meislik, MPBF Journal contributing editor (Whitefish, Montana)


                The choice of plants that can be grown depends upon the growing conditions that you can provide for your plants. In indoor growing we will confine our discussions to materials that can grow indoors and not temperate species such as pines and junipers that cannot be grown in most homes. Growing bonsai indoors can be accomplished in a number of ways:

          1.   Growing indoors in a room or windowsill

          2.   Growing plants outdoors in warmer weather and maintaining them indoors in the cooler months

          3.   Growing indoors full time under lights

          4.   Growing in a greenhouse or plant room

          5.   Growing outdoors full time in tropical and sub-tropical areas

            These are all vastly different growing environments. Fuku-Bonsai has specialized in developing plants that can and will grow indoors in most well lit rooms and windowsills. True Indoor Bonsai can be happy in most rooms if provided with 8-10 hours a day of bright room light but will grow more strongly if kept close to a south or west window or even more strongly if provided with supplemental artificial light. They can also grow extremely well outdoors full time in tropical and sub-tropical environments.

            The Dwarf Schefflera that you see in my living room window began as advanced stock material from Fuku-Bonsai. It can easily be grown in any well lit window in most homes.  Note that in the photo below, that my Dwarf Scheffleras are grown under other plants as they have a much lower light requirement.  

Basically I grow my tropical/indoor bonsai full time in a temperature and light controlled plant room. My plants never go outdoors and most have been in my plant room for over 13 years. I have hundreds of plants of many species in all stages of growth from finished bonsai to seedling starters.   I'll be including information about other plants that I grow in future Journal articles.  My room’s lighting is seven 1000 Watt metal halide lights that provide a lot of light intensity so that I can grow moderately high light loving trees. For more information about light, my article in the first issue of the Journal of Tropical and True Indoor Bonsai is posted at: 

            For many, artificial fluorescent lamps plus bright window light are an affordable recommendation for growing some of the lower-light tropical bonsai indoors.  Fuku-Bonsai’s True Indoor Bonsai can survive in locations away from windows, but will have superior growth with window light and with optional additional artificial light. Moving them outdoors for the summer will provide even stronger growth allowing faster styling and more design options.

            Please use caution when moving plants outdoors for the summer and warmer months. Plants grown indoors must be acclimated over 2-3 weeks to outdoor light. Initially plants should be in nearly full shade and moved to progressively sunnier spots over a 2-3 week period to prevent them from being sun-burned. Also use caution to be sure that the temperatures remain above 55-60F at all times. Watering will need to be monitored more closely as sun and wind can dry out a tree in a small pot very quickly.


Do tropical/indoor plants grow throughout the year? 

            Before answering this question I need to explain more about my growing conditions. At first glance growing in a plant-room year round, under artificial lights may seem to expose the bonsai to fairly constant year round environment. But under closer scrutiny growing conditions do vary somewhat. Seasonal factors do affect plants even when grown under fairly controlled and steady indoor conditions.

            TEMPERATURE.   As one might expect summer temperatures in the plant room are high and kept reasonable by ventilation. Still the average daytime temperature is higher in summer than winter.

            Heaters keep the minimum temperature at 65F year round but this is not approached on many nights in the summer as the plant room stays warm from heat accumulated during the warm days. Most winter nights the heater kicks on to keep the room at the 65F minimum. Summer nights may need ventilation to keep the room under 95F!

            DAY LENGTH.   This also varies from longer days in summer to shorter days in winter. Even though my overhead metal halide lights have a constant day set at 10 hours, 365 days a year with a light timer, outdoor window light still exerts an influence on most of the trees. I know this because:

            Plant growth slows down noticeably about September-October. June 21 is the summer solstice or the longest daylight of the year. 

            Plants initiate new growth about February, winter solstice is December 21 or the shortest daylight of the year. So plants begin growing or slowing down about 6-8 weeks after the days begin lengthening or shortening.

            Although the vast majority of light energy my plants receive is from the artificial lights the plants clearly do respond to total day length by adding up the hours from light through the windows and the artificial light!

            MANIPULATIONS. Plants that are repotted or trimmed back heavily may initiate new growth within a week or two regardless of the time of year. There is clearly some stimulus to initiate growth after heavy pruning, repotting etc.

            Many tropical plants that have natural adaptation to dry and wet cycles may at some time slow down their growth and even stop. At these periods allow them to go dryer than normal but keep lightly watering them before they get totally dry. They will likely drop leaves during this dry time but pretty quickly a new flush of growth ensues.


When is the best time for pruning and for repotting? 

            Light pruning can be done at any time of year. Light pruning involves removing some leaves, and some young green branches involving perhaps 15-20% of the plants green foliage mass but not heavy cuts into woody parts of the trunk. I would not do heavy pruning if the plants are in rest period. 

           Repotting can be done at any time of year in my plant room but conditions are so reliable that plants respond well despite the time of year. For growers who have their plants in windows and growers who grow their plants outdoors during warm weather I would suggest repotting when temperatures remain above 65F and growth of the plant is likely for the next 6-8 weeks due to continuing warm weather.

            Most tropicals prefer repotting during the early to mid summer while temperate species do best with a spring repotting – just before growth starts.



            Very few plants that I have grown are in continual growth. Many respond to seasonal cues even when grown indoors! Others respond with strong growth after pruning, leaf pruning or repotting. Others seem to slow down and rest for a few weeks. Observe your plants carefully and modify watering and fertilizing when plants let you know that they are resting. Tropical and sub-tropical plants do not have mandatory chilling requirements as do temperate species but even tropical do vary their growth and growth is not constant.

             I am delighted to be asked to be a contributing editor for the JOURNAL OF TROPICAL & TRUE INDOOR BONSAI as this becomes a major new form of American bonsai.  My monthly contribution will be called Bonsai Indoors – The Basics of Indoor Growing. Because the cultural requirements are so different from traditional outdoor temperate climate bonsai, a monthly online publication creates a vehicle to provide helpful information for those interested in being successful with these plants.  You are invited to visit my website at if you have questions or suggestions of topics you’d like to see addressed in the Journal or my website.  You can e-mail me at

             I look forward to hearing from you!  ~~~Jerry “Bonsaihunk” Meislik   


The Mid-Pacific Bonsai Foundation Journal of Tropical and True Indoor Bonsai is published monthly by email and is a benefit of Foundation membership. Annual dues are just $12 per year. For more information about becoming a member, go to

©   Jerry Meislik,  Fuku-Bonsai, and Mid-Pacific Bonsai Foundation, 2013