Indoor light

Thanks Iris thats really good to know! We use kelvin a lot at uni

I have used almost all types of lights there is for growing Bonsai and have to somewhat agree, lights in the higher Kelvin range is logically the better pick when it comes lights for indoor Bonsai, this since it will promote shorter internode spacing and smaller leafs thanks to the high amount of blue in the spectrum.

But i am not so sure if ~6500K, even if it works great really is the very best Kelvin temp for plants when using traditional light fixtures...

For example, i have seen my self and also heard other say that lower temp lights (~2700K) promote faster root-growth, faster fattening of branches, trunk and nebari witch is great! but it also promote bigger leafs and longer internode spacing witch we don't want...
So one can use a mix of lower and higher temp tubes to get the best of both worlds, ~6500K for tight growth and smaller leafs, and ~2700K for better root-growth and more, or a even better option is to use all ~4000K tubes, either of these 2 light setups may not get you the absolute smallest leafs possible compared to a all ~6500K setup, but IMO instead better overall growth, and it should also give you a little better CRI making the trees look even more green and lush.

Think it may be worth mentioning that even if ~4000K sound a long way from ~6500K, this is from what i remember the Kelvin temp of Metal halide lamps used by ex. Jerry Meislik and many other that grow top notch indoor Bonsai, so its proven.