Grow light for an Opuntia microdasys

[Brontosaurus]

I have this terribly stretched O. microdasys that I've posted about a couple of times before. My apartment, unfortunately, get's just very little natural light, and I live in a foggy area so what natural light it does get isn't very bright. I got a grow light for it, but it's this LED type thing that I doubt is bright enough to get the cactus healthy. You can see the picture of it with some other plants that aren't doing great. Can y'all recommend a grow light that would be good for it?

[esp_imaging]

Why do you have it so far away?
Move it much closer and it will be much brigher on the plants.

For a single LED with a normal micro reflector, if you move it twice as close, it's light will be 4 times as bright on the plants. The maths is harder with a panel array of lights, but closer = brighter applies very strongly.

Having white or silver reflectors around the plants will also make a big difference - I'm sure they would like a corner mirror set up!

Is the panel just blue lights?? Blue/red is a more common mix for grow light.

[Brontosaurus]

Thanks for the advice! That's a lot cheaper and a lot easier than buying another grow light!

The lights are blue and white. No idea why. They were that way out of the box.

[esp_imaging]

I have thought about this type of light panel, I think it could be good for a small seedling growing area.
I would have planned on having it maybe 15-30cm, from the surface of the pots, so really close, and that's just for seedlings. I'm just using a normal LED lightbulb for now, also close to the plants.

[Brontosaurus]

So the grow light even at a close level didn't seem to be helping, and since it's spring, I decided to move the cactus to a window sill. It still looked pretty miserable and a lot of the older pads died. I repotted all the new 'pads' (they are so skinny they can barely be called that) and took it out to the roof of my apartment complex. Not sure what else to do. Someone suggested it might be the humidity that is causing it to be so sad, but I've raised O. microdasys in a greenhouse before and it did okay. They're pretty frost tolerant and I've had them do fine at a climate zone 7. I don't know about humidity though. It is very humid in the area of China where I live. Any advice is awesome. Thanks! Hope you're all doing well. I don't post on here so much now that I don't work with plants anymore.

[esp_imaging]

I'm sure it will prefer being outside over summer.
I wonder if the blue light was a small part of the probleman issue too, most growlights have red and blue, with (I think) more red to blue.

[Pereskiopsisdotcom]

I don't quite understand the science with how light and grow lights work but I do know from practical application that the one you were using is probably not going to grow much of anything. Is one from eBay or Amazon? Fairly affordable? From my experience t5 HO grow lights are the most reliable for most cactus applications. If you do decide to go with LED because they can be more affordable try to aim for the Mars Hydro 300 model and the many imitators. It gets a lot of flak from the cannabis community for not being sufficient but I have found that for most small to medium sized cactus it is great and for seedlings it is often actually too strong.

[Brontosaurus]

I got it off Baopals, which is kind of like an ebay specifically for expats who live in China. If it's a hunk of junk I'm decidedly unsurprised.