UV grow light

[N.D.]

Every spring I lose some lithops to scorch. I think this is due to UV and not IR part of the spectrum, since this happens when air is still cool and it is hard to imagine plants getting overheated. Hence the idea to add UV LEDs to the grow light, so that the plants never lose UV-protecting pigments. Has anyone tried this? What wavelength should be used (234nm to 480nm is available)? What intensity? The biggest factor that might stop me from using it is safety. Looking at those plants under UV lights cannot be good for the eyes.

[el48tel]

I know what my optometrist would say about UV.

[SimonT]

Could this be cold damage instead?
If your plants are behind glass or plastic then quite a bit of the UV will be filtered out (depending upon the exact material)?

[N.D.]

This is definitely not cold damage, and they are not behind glass/plastic. I take them out when there is no threat of frost, i.e. when it is 10-15C outside. The damage happens during the day, usually when my temporary cover is blown away by the wind. Interestingly, it only happens to a handful of plants. Most survive it fine.

Could this be cold damage instead?
If your plants are behind glass or plastic then quite a bit of the UV will be filtered out (depending upon the exact material)?

[SimonT]

I don't grow lithops under lights but I've grown quite a few cacti. They tend to get quite spiny and compact under lights and
then when they come out from this they need a bit of time to adapt to less harsh conditions. I guess it depends upon the
exact setup you have. But I'm surprised you have this with lithops given where they grow in habitat.

[N.D.]

But I'm surprised you have this with lithops given where they grow in habitat.

Hm... What is it about habitat that makes them unsuitable for grow lights?

[SimonT]

If you are worried about scorch just shade your plants a bit when you first put them outside and gradually introduce more light.
Or even better put them through a 'hardening off' process.

[habanerocat]

This is definitely not cold damage, and they are not behind glass/plastic. I take them out when there is no threat of frost, i.e. when it is 10-15C outside. The damage happens during the day, usually when my temporary cover is blown away by the wind. Interestingly, it only happens to a handful of plants. Most survive it fine.

Could this be cold damage instead?
If your plants are behind glass or plastic then quite a bit of the UV will be filtered out (depending upon the exact material)?

The secret to avoiding scorch is no sudden changes in light intensity.