Is a grow light considered direct or indirect light? – House Plant Journal

Is a grow light considered direct or indirect light?

Plant Parent

I still don’t understand what they mean by indirect.

I use a grow light on my office plants because while I have a larger window in my office, and it’s even south facing, it’s mirrored on the outside and just isn’t enough.

I recently added hoyas and I am afraid of hurting them; does the further distance from the grow light make it indirect?


The distinction of direct vs indirect applies ONLY to the sun and, when dealing with indoor natural light, it is assumed that the window is mostly transparent (not highly tinted). Tinted windows will definitely result in weaker light.

The only way to clearly understand whether your plants are getting adequate light is to measure it.

I designed the LTH Meter to help plant parents understand their light in a concrete way.

I’ve written a lot more on the subject here: “Bright indirect light” requirements by plant

Plant Parent

The meter also says its not suitable to measuring grow lights, any suggestions?


Any light meter is suitable for measuring **white LED** lights (and natural light).

The only grow lights that aren’t perfectly measured by traditional lux meters are fluorescent, ceramic metal halide, high pressure sodium, and pure red/blue LED. As long as you’re using white LED grow lights, your regular light meter will work just fine.

Plant Parent

This was extremely useful thank you.

If you want to develop strong fundamentals in plant care, my book and online course will guide you in the right direction.