JasonRedwood
Mame
I am writing this post as documentation for techniques I implemented/implement for indoor bonsai growing. I know this is a taboo subject for a lot of people, especially if you’ve been growing trees for a long time. Keep an open mind, and be sure to read the “disclaimers” section before you hate-comment Even moreso if you're new and looking to grow plants inside it's not easy.
Due to my circumstances, I do not have a place to grow my plants outdoors as i live in an apartment. Additionally, I have some special insight because I am a physicist (no Ph.D yet though)
DISCLAIMERS:
I am not a bonsai master- I am simply recording what I myself do, in hopes that others may add to it, share advice, or learn something new.
I have several species of tree right now which are, Maple, Ficus natalensis, Juniper procumbens , Norfolk pine (1) (rescued from Home Depot), Poinsettia(1) (gift over Christmas), and Willow.
All of my trees are potted in diatomaceous earth mixed with small, sifted pine bark (except my juniper). I fertilize with generic 20-20-20 water soluble stuff.
Avid growers have told me that I cannot grow trees inside, and the following are the main reasons, light, humidity, air circulation, temperature, and dormancy. Here is how I’ve attempted to battle these things.
Light:
For reference, I am using the SI system of units, Google should convert to any silly lumens or foot candles you might want. Definitions [power]: Watts (W) or Joules per second (J/s), [Length]: Meters(m), [intensity]: joules/second/area (J/(s m^2)) or W/m^2, [Temperature]: Kelvin or Celsius or Fahrenheit K or C or F.
What I use: Right now I use 4 24W T5 bulbs @6,400K mounted overhead with reflective lining then two CFL bulbs as spotlights directed towards the center of my plant–area. See picture below.
Color:
A lot of people complain that florescent lights are not the correct color for plants, and that only full spectrum halide lights will do the trick. This is in general not correct. The two common types of chlorophyll cells (a,b) have highest rates of photosynthesis in the wavelengths of 400-500 nm and 600-700 nm. Though, it is true that leaves will absorb all wavelengths of light (except for the wavelengths we see as the color of the leaves, these are reflected – hence why we see them). It is best to try to match the Sun’s spectrum as closely as possible.
What is referred to as “color temperature” is actually an extremely physical concept. In physics, we call an object that emits radiation at a characteristic temperature a “black body”. Max Planck, a physicist long dead, figured out that you can describe the wavelength and energy of this radiation by only measuring this temperature. We all know this to be true, if you heat a fire poker up – “red hot” is cooler than “white hot”.
The Sun’s Characteristic temperature is about 6,500K if you're not on the poles or equator, so my 6,400K lights are pretty good.
Intensity:
There is an extreme amount of confusion in gardening communities about intensity or “brightness”. Intensity is power per area, or how much energy hits an area, every second. Light intensity is determined by the distance from the source, and the area we care about. It is worth noting that the area we actually mean is the leaf area of our plants which I’ll approximate to the area of my table.
The area of my plant table is .35 m^2 and my lights are .51 meters above the table or .27m above my shortest plant. I will include mathematical details in a link below, but intensity is in this case the average of the Poynting vector, or in other terms, the power divided by the area. I am making a large approximation here – my lights are actually about the same area as my table, which is not too bad for reasons explained in the link. Turns out, the intensity over the area of my table, on average is 275 W/m^2. Work is shown here. This does also only take into account my T5 lights.
It is worth noting that this is highly idealized – it does not take into account some thermal radiation produced by the lights, but this effect will be small with CFL and T5 lights.
Duration:
I keep my lights on an 18hr/day timer to make up for some of the intensity loss. Furthermore, my plant table is situated near a north and a west window, and gets “some” sunlight from those. Plants DO need to rest for a period of at least 6-8 hours every night. This was incredibly hard to research and I am going on what two master gardeners from the local arboretum have told me.
Light is always a big concern for leaf size and internode length. With my setup, my plants do not have *extremely* small leaves or short internotes – however, the leaves are no larger than the largest leaves of the trees of the same species outside. Keeping in mind I have not yet started to try to reduce leaf size.
Next issue: Humidity
Water in general can be an issue with indoor growing because of radiating heaters, and our typical AC units drying out the air. I am however, fortunate. I do not have air conditioning, at least not in the room the plants are in (one window unit in the bedroom, that does not cool the living space). During the summer I do not have large issues with low humidity in my apartment. During the winter however, it is very dry. I combat this by nightly misting of the plants. You might say, my soil will stay too wet if I mist every night, or that I might have mold issues. If we use a very free draining soil, the small amount of run-off from misting should not harm the plants in any way – and in fact, I water all my plants at night anyway, so they’re already moist when I mist.
Air circulation
This is another thing that is difficult to get down to with real science. Many will say trees need wind to survive – but from researching online, and speaking with master gardeners, I have only found this to be true in 2 situations. 1) Air circulation will help keep your plants free of mold. 2) very stale air will allow dust to accumulate on leaves, and is in general unhealthy for the plants. However, I do not do anything special for air circulation.
Temp:
Luckily, my apartment only varies between 65-75 degrees F, and in winter specifically, if it’s cooler, the spotlights provide some thermal energy.
Dormancy: The biggest issue
Through much research, I found on average trees need around 1,000 hours of dormancy *not just cold*, and every species varies for the exact hours.
I spent 3 months observing my refrigerator. I bought an inexpensive humidity gauge and used a digital thermometer which is able to upload temp data to a computer (from work). I played with the fridge until I got the temperature to have an average value of -2C or 29F. This is cold enough to allow dormancy, and the worse temperature for mold growth.
Starting October first, I cycled the plants in the fridge for increasing amounts of time, to mimic dropping nighttime temperatures. Starting November 1st I placed the plants in the fridge full time.
One large concern was humidity, as the fridge was very, very dry. However, I was able to raise the humidity to around the same level as my apartment by slight misting on the walls of the fridge. Furthermore, I placed plastic bags, *loosely* over the plants, so that any moisture they lost through transpiration would stick around. I also misted the outside of these bags.
I took the plants out nightly to check on them, checked for watering and signs of mold or freezing, and I also misted them very slightly. I did this until January 1st giving the plants a total of 1464-ish hours in the cold. All of the plants did enter true dormancy, as is evident from winter buds that formed on them., loss of leaves, etc. Additionally, all plants but one lived, and have now broken bud and are growing.
Issues:
I did lose one plant in the fridge. It was a willow cutting I had taken last spring. I may have lost it for two reasons – 1) The plant was not that healthy to begin with – I had to repot it in the early fall because I had dropped it and broke it’s pot. 2) the plant was an awkward shape and I could not cover it with a bag in the fridge so it may have dried out.
I also had my juniper freeze solid for a short time. Through evaporation, the water in the juniper’s pot was able to lose enough energy to freeze. As soon as I found the plant – which was rising out of the pot from the expansion of the water, I let it melt and settle back in. Covering the soil with a cloth prevented this in the future.
Here are a few photos.
Plants in the fridge, but not covered with bags (left). My plant table (center). Leaf size from one of the few hardened(ish) leaves of one of my maples. This was the largest leaf on the plant. I do not have any photos from last year, but they did not get much bigger than this - maybe the biggest was 6 cm. (right)
Here are some of my sources and helpful websites.
http://www.bonsaihunk.us/info/IndoorLight.html
http://photobiology.info/Chalker-Scott.html
http://hyperphysics.phy-astr.gsu.edu/hbase/biology/ligabs.html
Due to my circumstances, I do not have a place to grow my plants outdoors as i live in an apartment. Additionally, I have some special insight because I am a physicist (no Ph.D yet though)
DISCLAIMERS:
I am not a bonsai master- I am simply recording what I myself do, in hopes that others may add to it, share advice, or learn something new.
- Indoor growing is NOT OPTIMAL. This method of growing is more expensive, more time consuming, slower, and will always produce extra challenges to overcome. It is not for the faint of heart.
- All of my trees are “pre-bonsai”. Therefore, I will focus more on the general requirements of the trees.
- I do not wish to create “show quality” bonsai: In the same way that I love playing piano, but do not want to be a concert pianist. My trees are for me, they are my expression, and only need to look good enough for myself, and myself alone. Many of the species and styles i use are not typical, and that is ok with me.
I have several species of tree right now which are, Maple, Ficus natalensis, Juniper procumbens , Norfolk pine (1) (rescued from Home Depot), Poinsettia(1) (gift over Christmas), and Willow.
All of my trees are potted in diatomaceous earth mixed with small, sifted pine bark (except my juniper). I fertilize with generic 20-20-20 water soluble stuff.
Avid growers have told me that I cannot grow trees inside, and the following are the main reasons, light, humidity, air circulation, temperature, and dormancy. Here is how I’ve attempted to battle these things.
Light:
For reference, I am using the SI system of units, Google should convert to any silly lumens or foot candles you might want. Definitions [power]: Watts (W) or Joules per second (J/s), [Length]: Meters(m), [intensity]: joules/second/area (J/(s m^2)) or W/m^2, [Temperature]: Kelvin or Celsius or Fahrenheit K or C or F.
What I use: Right now I use 4 24W T5 bulbs @6,400K mounted overhead with reflective lining then two CFL bulbs as spotlights directed towards the center of my plant–area. See picture below.
Color:
A lot of people complain that florescent lights are not the correct color for plants, and that only full spectrum halide lights will do the trick. This is in general not correct. The two common types of chlorophyll cells (a,b) have highest rates of photosynthesis in the wavelengths of 400-500 nm and 600-700 nm. Though, it is true that leaves will absorb all wavelengths of light (except for the wavelengths we see as the color of the leaves, these are reflected – hence why we see them). It is best to try to match the Sun’s spectrum as closely as possible.
What is referred to as “color temperature” is actually an extremely physical concept. In physics, we call an object that emits radiation at a characteristic temperature a “black body”. Max Planck, a physicist long dead, figured out that you can describe the wavelength and energy of this radiation by only measuring this temperature. We all know this to be true, if you heat a fire poker up – “red hot” is cooler than “white hot”.
The Sun’s Characteristic temperature is about 6,500K if you're not on the poles or equator, so my 6,400K lights are pretty good.
Intensity:
There is an extreme amount of confusion in gardening communities about intensity or “brightness”. Intensity is power per area, or how much energy hits an area, every second. Light intensity is determined by the distance from the source, and the area we care about. It is worth noting that the area we actually mean is the leaf area of our plants which I’ll approximate to the area of my table.
The area of my plant table is .35 m^2 and my lights are .51 meters above the table or .27m above my shortest plant. I will include mathematical details in a link below, but intensity is in this case the average of the Poynting vector, or in other terms, the power divided by the area. I am making a large approximation here – my lights are actually about the same area as my table, which is not too bad for reasons explained in the link. Turns out, the intensity over the area of my table, on average is 275 W/m^2. Work is shown here. This does also only take into account my T5 lights.
It is worth noting that this is highly idealized – it does not take into account some thermal radiation produced by the lights, but this effect will be small with CFL and T5 lights.
Duration:
I keep my lights on an 18hr/day timer to make up for some of the intensity loss. Furthermore, my plant table is situated near a north and a west window, and gets “some” sunlight from those. Plants DO need to rest for a period of at least 6-8 hours every night. This was incredibly hard to research and I am going on what two master gardeners from the local arboretum have told me.
Light is always a big concern for leaf size and internode length. With my setup, my plants do not have *extremely* small leaves or short internotes – however, the leaves are no larger than the largest leaves of the trees of the same species outside. Keeping in mind I have not yet started to try to reduce leaf size.
Next issue: Humidity
Water in general can be an issue with indoor growing because of radiating heaters, and our typical AC units drying out the air. I am however, fortunate. I do not have air conditioning, at least not in the room the plants are in (one window unit in the bedroom, that does not cool the living space). During the summer I do not have large issues with low humidity in my apartment. During the winter however, it is very dry. I combat this by nightly misting of the plants. You might say, my soil will stay too wet if I mist every night, or that I might have mold issues. If we use a very free draining soil, the small amount of run-off from misting should not harm the plants in any way – and in fact, I water all my plants at night anyway, so they’re already moist when I mist.
Air circulation
This is another thing that is difficult to get down to with real science. Many will say trees need wind to survive – but from researching online, and speaking with master gardeners, I have only found this to be true in 2 situations. 1) Air circulation will help keep your plants free of mold. 2) very stale air will allow dust to accumulate on leaves, and is in general unhealthy for the plants. However, I do not do anything special for air circulation.
Temp:
Luckily, my apartment only varies between 65-75 degrees F, and in winter specifically, if it’s cooler, the spotlights provide some thermal energy.
Dormancy: The biggest issue
Through much research, I found on average trees need around 1,000 hours of dormancy *not just cold*, and every species varies for the exact hours.
I spent 3 months observing my refrigerator. I bought an inexpensive humidity gauge and used a digital thermometer which is able to upload temp data to a computer (from work). I played with the fridge until I got the temperature to have an average value of -2C or 29F. This is cold enough to allow dormancy, and the worse temperature for mold growth.
Starting October first, I cycled the plants in the fridge for increasing amounts of time, to mimic dropping nighttime temperatures. Starting November 1st I placed the plants in the fridge full time.
One large concern was humidity, as the fridge was very, very dry. However, I was able to raise the humidity to around the same level as my apartment by slight misting on the walls of the fridge. Furthermore, I placed plastic bags, *loosely* over the plants, so that any moisture they lost through transpiration would stick around. I also misted the outside of these bags.
I took the plants out nightly to check on them, checked for watering and signs of mold or freezing, and I also misted them very slightly. I did this until January 1st giving the plants a total of 1464-ish hours in the cold. All of the plants did enter true dormancy, as is evident from winter buds that formed on them., loss of leaves, etc. Additionally, all plants but one lived, and have now broken bud and are growing.
Issues:
I did lose one plant in the fridge. It was a willow cutting I had taken last spring. I may have lost it for two reasons – 1) The plant was not that healthy to begin with – I had to repot it in the early fall because I had dropped it and broke it’s pot. 2) the plant was an awkward shape and I could not cover it with a bag in the fridge so it may have dried out.
I also had my juniper freeze solid for a short time. Through evaporation, the water in the juniper’s pot was able to lose enough energy to freeze. As soon as I found the plant – which was rising out of the pot from the expansion of the water, I let it melt and settle back in. Covering the soil with a cloth prevented this in the future.
Here are a few photos.
Plants in the fridge, but not covered with bags (left). My plant table (center). Leaf size from one of the few hardened(ish) leaves of one of my maples. This was the largest leaf on the plant. I do not have any photos from last year, but they did not get much bigger than this - maybe the biggest was 6 cm. (right)
Here are some of my sources and helpful websites.
http://www.bonsaihunk.us/info/IndoorLight.html
http://photobiology.info/Chalker-Scott.html
http://hyperphysics.phy-astr.gsu.edu/hbase/biology/ligabs.html
. Sorry; Not wanting to be argumentative, but I just disagree with you 
