It really looks like a burn, by heat or light.

I think so too Garrett, they look fried crisp. But I really can't see that happening on windowsill in z6.

I am in colder zone, but we are having a much hotter and drier summer this year. It has been also very humid, humidity often being in nineties. It does fluctuates a lot, but it is very high. All my jades are outdoors, in full sun and none of them suffered such burns. I have some sun damage on few leaves, but nothing to compare to above:

I'm glad it looks more like a burn than some sort of disease! They were about 4-5 inches from the lights, with no fan on them. It's completely anecdotal, but putting my hand under the lights vs. in the windowsill, it was somewhat warmer under the lights. (Also, the windowsill gets air from outside; the windows are always open, but the interior of the apartment stays warmer than the outside temps.) For what it's worth, the lights are on 15 hours a day.

The windowsill I have them in now faces mostly east, so they get full sun in the morning but shade later in the day. They haven't been there long enough for me to see if this is helping, but I guess I'll see!

I water them about once a week; the gritty mix gets dry after just a few days. Would watering more often (or less often) help them recover, or does this sound like a reasonable schedule?

Michael

Do not water more often than when soil dries up, if there is a reason for sunburn, it isn't the watering. What I was guessing about is that I wonder about waterlogged leaves - since they are full of water, would they burn (fry) faster and worse? - but I have no idea.

In gritty mix, you should water thoroughly when needed - check the mix for dampness (you can help yourself with a bamboo skewer, or chopstick or even pencil). Depending on what your mix is made of and the temp and humidity of environment they are in, it could be every few days or longer.

The burn can't be repaired, the leaves will eventually fall off. You could snip them off too if you can't live with them:).

I still wonder about the lights: 4-5" from the tubes still shouldn't cause that kind of burn. I have burned echeveria badly by having it close to CFL, but that is more 'sensitive' pant and it was less than 2" away from the bulb. Kevin (ewwmayo) uses H5TO and has some great notes/measurements somewhere on this forum...Hopefully he will see this post and posts his thoughts-facts.

I just took few photo; here is the Gollum, in full sun from sunrise until about 6pm. If anything, there is little more yellow on the leaves, but nothing alarming:

'Regular' jade right next to it - great color IMO, no burns:

This one (Blue bird? Waves? - not sure) has more delicate/thinner leaves and got damage in same location - I moved it & it gets sun until about 12:30-1pm now:
I am still wondering if your plants got sprayed by anything: rubbing alcohol? any pesticide? leaf shine? fertilizer solution? anything else?

I can't remember for sure if these were sprayed or not; a couple months ago (a good 3 or 4 weeks before I started noticing anything on these plants), I did spray some plants that showed signs of mealies with a mixture of about 30% isopropyl alcohol (the rest water, with a drop of dish soap). I can't remember if these were among those that got sprayed. I did watch all the plants after spraying, though, to see if I saw any yellowing or leaf damage, and saw nothing...could it have been delayed by 3–4 weeks?

I don't think it would take that long....bit of a mystery :) Your solution was relatively weak, I use r. alcohol full strength sometimes. It is generally recommended to keep plants out of direct sunlight if spraying.

If the water used contains lots of salts & minerals, it could also show as some spots on the leaves - but you should have seen it on many plants and for a while, I think.