what grow lights can be used for bonsai trees?

[ShadyStump]

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.View attachment 416153

I have a couple very similar to these from Sansi that I got used from my brother when he upgraded.
They can get VERY hot, but the light output is incredible.

It might help if we explain a little of the terminology.
PAR/PPF is the rating for how much photosynthetic light they put out. There are two methods of measuring this, and you need to know which one the manufacturer is giving you. If the don't specify, a little reasoning will let you figure it out.
First, there's the maximum PAR/PPF. This is measured at the exact spot under the light where the photosynthetically active radiation (PAR) is at it's highest. It will always come off looking like a very high number, but if you're lighting a big area vs a single tree it's not very helpful.
Second is average PAR/PPF. They essentially set the light up in a 2x2x2 foot grow tent, and measure the light at various points across the bottom and give you the mean. The number will appear lower, but will give you a much better idea of how it'll work for multiple trees.
There are many ways manufacturers can cheat to make the numbers look better, so stick with reputable brands until you get a better idea what you're looking for.

Color temperature tells you what ends of the visible light spectrum you're working with measured in degrees Kelvin. The sun on a clear day is pushing 7000 degrees K. The natural daylight lightbulbs are usually around 6000K.
Here's where it messes with your head. The higher the number, the cooler the color. As in high numbers lean more to the blue end of the spectrum. Lower numbers are softer, warmer light, more towards the red and yellow end.

 

[Paradox]

I am with Leo in that I am also a "dinosaur" using a T5 fluorescent set up. I have used this set up for several years for my Brazilian Rain trees and my ficus and it just works so I have no reason to change it. My BRT and ficus grow most of the winter under my lights. I also agree with making them adjustable in height which can easily be done with a screw eye or loop hung from the ceiling, decorative chain and some S hooks

 

[Ugo]

Hi!

I did my researchs on lightning setup and tried to found compromise between lots of factors.
You will see this subject is vast, complex but it has been studied for farmers and industry we're all the infornations means a lot of money and better crops.
To resume for our specific needs:

What @ShadyStump says is right on spot.

To give you more infos.

You will have a choice between LED lights or T5 neons for most common inside growing setup.

Depending on what you need T5 full spectrum neon can be the best in term of "lenght" for example you have long bences to light up but the regular T5 neons have to be replaced after a year I think. (Please correct me if Im wrong!)
LED offer you square shape units, last longer?, but they are more expensive.

Two major things to consider for choosing the right equiment

The PPFD rating your tree needs (density of photons given at X height and size from the light) and the spectrum of the light your tree needs given by the light you choose PAR.

For me the PPFD rating you choose will be influenced by 2 majors reasons.

First reason is the PPFD rating the tree need. It can get really technical but to simplify that means if the tree need alot of light, medium, low but in term of "density" more then time.
2 different readings of PPFD can be taken: instant which will be given in µmol m-2 s-1 and daily.
When buying a lamp its the mesurement they will give for a given height example 14in to a given area example 3x3ft.
For example my ficus react well to 800 µmol m-2 s-1.
PPFD seconds as above can be calculated to know the daily requirement for a given tree which will lead you to the time you have to set the lamp ON for optimal conditions in the current season ect... (too technical for me its a ballpark)

The second reason that will help you choose the right PPFD light rating for your tree is the distance available from the top of tree to the light.
For example the lamp as to be set at 14in from the top of my tree to give it 800 µmol m-2 s-1.
If my grow tent or space or ceiling / height of the tree only allow me to install it at 10in there's a risk of shocking the tree, burn leaf, stop photosynthesis ect.
So I will choose another light source that can fit my actual setup.


For the the spectrum of the light your tree needs given by the light you choose PAR.
It also depends on your tree, for a vegetative tree I read the "blue spectrum" is more absorbed.
For a tree with flowers the "red spectrum" is more appreaciated.
That's why you see "purple" led light boards on sale everywhere.
But some studies have showns that a tree, plant ect can use a variety of other colors and infra red in the spectrum.
So now you have "full spectrum" lights for sale, more 'natural' light, the sun spectrum is not possible to reproduce, artificial light is a compromise.
Depending on the type of tree a different full spectrum will be prefered if you want "optimum" conditions.
For example my ficus is a vegetative tree only and doesnt produce flowers.
Here's 2 PAR charts "full spectrum"





Both will be good for vegetative plant, good overall spectrum but the first one will help a bit more towards blooming, flowering at the expense of the green spectrum intensity (the green spectrum is the one used the least, the one "reflected" by plants.
More recent studies shows that "green" is still used by plants to some extends.

I suggest you to collect some basic data just to invest into a setup you need, not necessesary expensive but the one your tree will like.
There's no such thing as buying a 1500w light with 5x COB led light with the wrong spectrum ,installing it at 10in from the top of the tree, and burn the top foliage in 12hrs for absolutely nothing.
That's expensive!! An IKEA light would have been better in this case.

To give you a starting point here 2 lights I would buy for vegetative tree like a ficus in a small grow tent where overall temperature inside could be an issue.

Spider farmer F1000
Mars Hydro TS 1000

There's some advanced members here that can give you better advices than me but this is what I understood from my readings.

 

[19Mateo83]

I’m currently using t5 HO lights for my experiment/cutting area. So far so good. Don’t mind the Gensing ficus, they were in the throw away garbage can at lowes. Couldn’t help myself