CactiGuide.com

I'm new to Cactus growing. I did my research and started growing Saguaro seedlings about 6 months ago. Everything has been going good and have many seedlings of varying sizes. Since being uncovered, I have been giving them a nice watering from the bottom about once a week, while spraying the tops every few days to keep from getting too dry (since they are young). But lately one will begin rotting into the soil, while the ones around it are still looking good. Is this a normal thing? Or is something I'm doing causing this to happen?

Trying to post a picture but file is too large. Thank you for any replies.

I'll just comment on the photo being too large. I use https://picresize.com to edit my pictures down to a max file size of 500 kb in order to post them here on this site. Steps you need to take. You have to upload the photo to picresize. Then set settings to best quality and 500 kb max file size. Click resize and then download the small photo back to your computer within 10 minutes. They don't store photos. Once there you can upload here.