Rotting Mammillaria elongata

[Gail]

My M. elongata has been looking a bit sad the last week so I checked its roots tonight. Not only had the roots rotted off but it was traveling up the stem. I cut the good ends off and am letting them dry before placing in the rooting medium.

I really like this cactus and would like to trouble shoot why this happened. It was a new plant that I replanted in pure floor dri and watered about once a week. Its been living outside for the last couple weeks though and when I water the lawn, the sprinkler hits the porch where the cactus are. Its also been unusually hot the last week, in the high 80's-low 90's. Do you think it was the water, the heat or a combo of both?

With it being this hot, where should I place it while it roots? I have a lighted plant shelf in the bedroom with low humidity. Or I can place it on the porch in the shade and out of the sprinkler.

[sundanz]

I would put it in the bedroom under lights. The sprinkler might have been the problem. I have 2 of them in my GH where it gets around 94, sometimes 100 right now. I water every few days!
Good luck
Karin

[Gail]

Will do, thanks:)