More Astrophytum coahuilense x ornatum seedlings have germinated. The oldest ones now look like little pink hearts. The grow light bulbs are a tiny bit too strong for cactus seedlings, but the redness here is still within the normal range. At least they aren’t stretching for light, which is arguably worse.
So far I have only seen mold on a couple of seeds and it’s especially visible when I use the macro lens for my phone. I’m keeping an eye on that, because I don’t want it to spread to the healthy seedlings. I’ve managed to keep it down to a minimum by washing the seeds in hydrogen peroxide before I tried to germinate them. I make sure to vent the little greenhouse I keep them in, by taking the lid off for half an hour each day, too.