what grow lights can be used for bonsai trees?

[Joyce2021]

I am building an indoor greenhouse for bonsai trees. What grow light would you recommend?

Thank you.

 

[ShadyStump]

Depends on what trees, the location in the house, the space, your budget, etc., etc., etc.

We'll need to know more before we can help.

 

[penumbra]

Lots of choices but LED Quantum boards are receiving high accolades currently.
But really, there are more choices than you can imagine. Look on Amazon.
Better yet, if you can afford it visit a grow shop. There are hydroponic stores and such everywhere.

 

[RJG2]

I know a few of us are very happy with LED grow lights by HLG.

 

[penumbra]

Let us know more about your proposed set up and we can offer more advice. An indoor greenhouse is something of an anomaly.

 

[MaciekA]

IMO most grow light setups are still inferior to sunlight even if you're using HLG panels each at 500W a pop.

Given that, I think the advice should be to maximize the number of watts you are able to fit into a budget and to seek out panels that explicitly state which LED emitters they are using (as in: who manufactured them -- Samsung, Epistar, etc. There are only a handful of these globally).

Another poster mentioned HLG lights, which I think are a good horticultural-grade reference product to compare to.

If you want something with a similar quality of output as the HLG lights, look for lights that use the Samsung lm301a or lm301h LED emitters. If a panel uses these, 9 times out of 10 it'll be proudly stated in the product specs. After that, all you need to do is maximize the quantity of emitters (i.e. the number of individual boards attached to the metal plate on the panel) that fits your budget.

If you want HLG knockoff lights that use the same Samsung emitters as HLG does (and I'm 99% certain are assembled by the same exact people in the same exact factory given that the power bits say "HLG" on them, cough) take a look at Shenzhen Meijiu Lighting Co on Alibaba.

 

[Joyce2021]

IMO most grow light setups are still inferior to sunlight even if you're using HLG panels each at 500W a pop.

Given that, I think the advice should be to maximize the number of watts you are able to fit into a budget and to seek out panels that explicitly state which LED emitters they are using (as in: who manufactured them -- Samsung, Epistar, etc. There are only a handful of these globally).

Another poster mentioned HLG lights, which I think are a good horticultural-grade reference product to compare to.

If you want something with a similar quality of output as the HLG lights, look for lights that use the Samsung lm301a or lm301h LED emitters. If a panel uses these, 9 times out of 10 it'll be proudly stated in the product specs. After that, all you need to do is maximize the quantity of emitters (i.e. the number of individual boards attached to the metal plate on the panel) that fits your budget.

If you want HLG knockoff lights that use the same Samsung emitters as HLG does (and I'm 99% certain are assembled by the same exact people in the same exact factory given that the power bits say "HLG" on them, cough) take a look at Shenzhen Meijiu Lighting Co on Alibaba.

Thank you so much! This is very helpful.

 

[Leo in N E Illinois]

I am building an indoor greenhouse for bonsai trees. What grow light would you recommend?

Thank you.

You have gotten excellent advice on types of lights. Myself, I'm a dinosaur, still using T-5 set up.

But there are some other things to consider in your designs.

1.) Air Movement - one or more small to medium size fans in your growing area are essential for good plant health. Not just trees, all plants growing under lights will benefit. Aim breeze from fan(s) so that anywhere in the growing space a thin leaf grass plant would wave gently in the breeze. Most trees will tolerate 30 mph wind, but that would annoy us humans. A light gentle breeze over the whole growing space is the goal. This will keep insect & mite pests down, and promote healthy roots, fewer problems with fungus and bacteria. Air exchange is good. A sealed, air tight space is usually not good.

2.) Timers - put the lights on a timer. You can to some extent make up for lower output of lights compared to sunlight by using longer day length. Maximum useful day length is 18 hours. Most of us set our lights on 18 hours on, 6 hours off.

3.) Humidity - I come to bonsai from raising orchids. I found generally I get better growth, particularly root growth if humidity is above 40%. This is not that difficult to achieve. Also it is important to keep humidity below 85% or 90% as fungal and bacterial issues will become a problem if you enclose your area and seal it too tight.

Critical note: a group of plants under lights will "generate it's own weather". Once my orchid collection went over 250 plants grouped together under lights they created their own humidity. I no longer needed to add humidity. What was needed was an exhaust fan to the outside. I did not do this. Now 30 years later I have rotting wood window sashes due to the excess condensation from the years of high humidity in the house. During our cold winters there is always moisture dripping off my windows inside the house. Of course my orchid collection was a bit out of control, over 1000 plants for quite a number of years. I've scaled back now, but the damage is done to the house.

So vent excess humidity outside if your collection gets larger than 300 plants.

 

[Joyce2021]

You have gotten excellent advice on types of lights. Myself, I'm a dinosaur, still using T-5 set up.

But there are some other things to consider in your designs.

1.) Air Movement - one or more small to medium size fans in your growing area are essential for good plant health. Not just trees, all plants growing under lights will benefit. Aim breeze from fan(s) so that anywhere in the growing space a thin leaf grass plant would wave gently in the breeze. Most trees will tolerate 30 mph wind, but that would annoy us humans. A light gentle breeze over the whole growing space is the goal. This will keep insect & mite pests down, and promote healthy roots, fewer problems with fungus and bacteria. Air exchange is good. A sealed, air tight space is usually not good.

2.) Timers - put the lights on a timer. You can to some extent make up for lower output of lights compared to sunlight by using longer day length. Maximum useful day length is 18 hours. Most of us set our lights on 18 hours on, 6 hours off.

3.) Humidity - I come to bonsai from raising orchids. I found generally I get better growth, particularly root growth if humidity is above 40%. This is not that difficult to achieve. Also it is important to keep humidity below 85% or 90% as fungal and bacterial issues will become a problem if you enclose your area and seal it too tight.

Critical note: a group of plants under lights will "generate it's own weather". Once my orchid collection went over 250 plants grouped together under lights they created their own humidity. I no longer needed to add humidity. What was needed was an exhaust fan to the outside. I did not do this. Now 30 years later I have rotting wood window sashes due to the excess condensation from the years of high humidity in the house. During our cold winters there is always moisture dripping off my windows inside the house. Of course my orchid collection was a bit out of control, over 1000 plants for quite a number of years. I've scaled back now, but the damage is done to the house.

So vent excess humidity outside if your collection gets larger than 300 plants.

Thank you so much for sharing these excellent tips!!!

 

[Joyce2021]

Thank you so much for sharing these excellent tips!!!

You have gotten excellent advice on types of lights. Myself, I'm a dinosaur, still using T-5 set up.

But there are some other things to consider in your designs.

1.) Air Movement - one or more small to medium size fans in your growing area are essential for good plant health. Not just trees, all plants growing under lights will benefit. Aim breeze from fan(s) so that anywhere in the growing space a thin leaf grass plant would wave gently in the breeze. Most trees will tolerate 30 mph wind, but that would annoy us humans. A light gentle breeze over the whole growing space is the goal. This will keep insect & mite pests down, and promote healthy roots, fewer problems with fungus and bacteria. Air exchange is good. A sealed, air tight space is usually not good.

2.) Timers - put the lights on a timer. You can to some extent make up for lower output of lights compared to sunlight by using longer day length. Maximum useful day length is 18 hours. Most of us set our lights on 18 hours on, 6 hours off.

3.) Humidity - I come to bonsai from raising orchids. I found generally I get better growth, particularly root growth if humidity is above 40%. This is not that difficult to achieve. Also it is important to keep humidity below 85% or 90% as fungal and bacterial issues will become a problem if you enclose your area and seal it too tight.

Critical note: a group of plants under lights will "generate it's own weather". Once my orchid collection went over 250 plants grouped together under lights they created their own humidity. I no longer needed to add humidity. What was needed was an exhaust fan to the outside. I did not do this. Now 30 years later I have rotting wood window sashes due to the excess condensation from the years of high humidity in the house. During our cold winters there is always moisture dripping off my windows inside the house. Of course my orchid collection was a bit out of control, over 1000 plants for quite a number of years. I've scaled back now, but the damage is done to the house.

So vent excess humidity outside if your collection gets larger than 300 plants.

I saw some LED guides mentioned the light should be hung 12 inches above plants. What's the distance you keep?

 

[Tums]

I saw some LED guides mentioned the light should be hung 12 inches above plants. What's the distance you keep?

That really depends on the output of the grow light. I bet the lights recommended in this thread would be too strong at 12 inches. I have one of these light meters https://www.ebay.com/itm/202866564304 which helps me determine what distance to hang the lights at. As a reference, 10k footcandles is roughly equivalent to full blazing sun outdoors, and 1k FC is roughly the brightness of shade open to the sky. I've had trouble with anything over 4-5k FC even for my cacti. My plants seem to be doing alright for overwintering purposes with 2-3k FC (growing slowly but not stretching).

 

[Leo in N E Illinois]

My advice for height of lights above the plants. Make the height of the fixtures adjustable. If you have a sturdy leaf houseplant like a Cattleya orchid, or a sansevieria, (lay the leaf horizontal) hang the fixture at the test height. Let the lights run for 15 minutes with the fans on as you would normally. Clamp the leaf in the palm of your hand (close your fingers pressing the leaf to your palm). If the heavy leaf of the orchid or the sansevieria feels cool to the touch, then the light is not too close. You can then lower the light some more and check again. You can set the lights with the orchid or the sansevieria and then switch them out for your bonsai. This is the primitive touch method.

Having fans on will allow you to have the lamps closer to the trees, effectively allowing them to get more light. With deciduous trees like elms or pomegranates, where they replace leaves rapidly, you just keep lowering the lights until the leaves burn, then back off a little and that will be "max sun" for your set up. Use the "touch method" above to get close, then fine tune your height using an elm or pomegranate or other rapid growing tree that replaces burnt leaves quickly.

 

[Leo in N E Illinois]

The leaves on the tops of your trees will be the closest to the lights, these will be the ones to burn first. These will be the ones to watch.

Brazilian rain tree is another tree that is excellent under lights, and anytime any foliage is damaged, it replaces damaged foliage quickly.

 

[Joyce2021]

My advice for height of lights above the plants. Make the height of the fixtures adjustable. If you have a sturdy leaf houseplant like a Cattleya orchid, or a sansevieria, (lay the leaf horizontal) hang the fixture at the test height. Let the lights run for 15 minutes with the fans on as you would normally. Clamp the leaf in the palm of your hand (close your fingers pressing the leaf to your palm). If the heavy leaf of the orchid or the sansevieria feels cool to the touch, then the light is not too close. You can then lower the light some more and check again. You can set the lights with the orchid or the sansevieria and then switch them out for your bonsai. This is the primitive touch method.

Having fans on will allow you to have the lamps closer to the trees, effectively allowing them to get more light. With deciduous trees like elms or pomegranates, where they replace leaves rapidly, you just keep lowering the lights until the leaves burn, then back off a little and that will be "max sun" for your set up. Use the "touch method" above to get close, then fine tune your height using an elm or pomegranate or other rapid growing tree that replaces burnt leaves quickly.

I will try that. Thank you.

 

[Joyce2021]

That really depends on the output of the grow light. I bet the lights recommended in this thread would be too strong at 12 inches. I have one of these light meters https://www.ebay.com/itm/202866564304 which helps me determine what distance to hang the lights at. As a reference, 10k footcandles is roughly equivalent to full blazing sun outdoors, and 1k FC is roughly the brightness of shade open to the sky. I've had trouble with anything over 4-5k FC even for my cacti. My plants seem to be doing alright for overwintering purposes with 2-3k FC (growing slowly but not stretching).

Thank you.

 

[penumbra]

You have gotten a lot of good advice here although it is piecemeal and posters are trying to guess what kind of set up you are planning on. Do you in actuality have a plan or are you putting it together based upon the information you are receiving here? Just curious as the cart is so far out in front of the horse that I can't keep up.

 

[Glaucus]

All lights can be used as long as they provide visible light. Any photons between 400 and 700 (approximately), a plant will use for photosynthesis.
But, growing a bonsai indoors is a different matter.
I recommend it only for indoor plants, seedlings, and cuttings.

I just set up my 2 by 1.5m grow box. I use a Grow 300 by Grow Light Science. It has basically the same efficiency as a top HLG light, but for a way lower price. Only the superduper high end LEDs have better efficiency.

Quantum boards are great for smaller and cheaper grow areas. Don't buy a random light off Amazon. Buy one that has been independently tested on for example Youtube with a proper light PAR sensor.
What you should buy depends on the area and the light intensity you want there. Only with that info, people can recommend specific lights.

Light is the easy thing, I would say. Humidity and proper ventilation are harder to manage and control. As are pests like fungus gnats.

 

[cmeg1]

IMO most grow light setups are still inferior to sunlight

I have definately observed this………once outside the small pines put on growth that I just do not see in the grow tents…..even with co2 fertilization…….tents are definately good experimental devices though for starters

 

[Diggumsmack2]

I am building an indoor greenhouse for bonsai trees. What grow light would you recommend?

Thank you.

I've been experimenting with GE growlight led with PAR 38 base(normal screw in bulbs). Basically it looks like a floodlight bulb. In my opinion, visually, these are the closest I've seen to natural sunlight. Unfortunately they are not cheap at 40+usd a pop. Picked these up at my local Lowes.

In my short time using them, I'm very happy with the performance. I had one initially and got a second because I was impressed with the light temperature and output.

 

[Michigan Bonsai]

HLG 65 V2 4000K Horticulture... https://www.amazon.com/dp/B076QDKVDZ?ref=ppx_pop_mob_ap_share

just got these last week after asking for advice on a separate thread. I can’t give feedback other than it seems they focus on the lightening system rather than what around it (no timer, no remote, etc…)
Also I tested them and it is really bright!

I expect to have trees at least 12” from the light