Good afternoon,

We have had a number of Sempervivum rot out due to high heat and humidity. (Guessing) We have had 95+ and high humidity. Most days for the past 2 months were above 85 and closer to 90+. Not Houston, lol, but not their usual mountain top home.

It reached a point where the only water they received was the rain. Stopped watering everything that wasn't a fern or a banana plant.
I never watered them heavily to begin with. Maybe once a week if it had been hot and dry all week at the beginning of summer. They are growing in clay 6 and 8 inch containers.
Mostly 60% sharp sand and 40% miracle gro without water polymers. (I know about pumice now. Ordered several bags but haven't had time to repot everything. Work out of town M-F most weeks.

As little as 5 hours Sun for a few of the containers, but that didn't seem to make a difference. Some in prime locations rotted. Some in lousy locations did fine.

Is rotting likely to be less of a problem in winter in zone 7B 8A?

Lol, most of the trees are deciduous. So they will get more sun in the winter than they do in the summer.

Thanks!

I find the mulch of crushed stone or chick grit is the most help on rotting as it prevents splash back of soil on the rosettes and keeps a cooler root zone.

Pots warm up much more than plants in the ground so I would go to that if that's a possibility.

Some rotten leaves are typical at this time of year and again in spring after a long wet winter. Although I don't clean my plants of these leaves, others are more meticulous about removing them to prevent rotting of the whole rosette.

I have a friend in Richmond VA who grows them very well in your area in raised beds.

Kevin

Usually in my area once temps starts hitting 90F and higher my semps gets too heat stressed, so either they bolt or eventually go dormant. Watering will not perk them up till temps return to cooler levels like 65F to 80F range. But my area is not humid, zero rain here for 6 to 7 months..so it is just relentless daytime heat, and hot air. But once they perk up in late Fall to Spring, even if it rains intermittently they do just fine. So my media is always very well draining and porous. I use cacti mix, and add more pumice to it.

I find semps drought tolerant but not that heat tolerant so once we start our hot and dry period where light levels are much longer and more intense, I have to reposition them in bright areas away from direct sun. Just have to be patient as it endures summer. It is indeed a bit tricky since once they go dormant, they are not drinking too much..so intervals in watering is done. Cannot make them too bone dry either, otherwise I will end up with crunchy dead semps. So to your question whether rotting of leaves is seasonal, yes, but you can work around it..position in a bright area, maybe under an umbrella, and do not overwater. Once those leaves starts closing down it is trying to save moisture and that is a visual sign be careful with watering.

Rainy summers are challenging..with the higher humidity, so hopefully you have an awning to protect them from excessive rainfall and still allow good airflow around it, to lessen fungal issues.

If you have time and patience, removing the older lower leaves that have naturally wilted away is also good, so you can further see if there are no critters hiding in between that is sucking the life out of your plant. This would be a regular maintenance you would need to do from time to time to keep them aesthetically pleasing as well.

Matt, can you post us a photo or two of your semps? It might help to understand what is going on. I like that you are using clay pots, instead of plastic or glazed pots. The clay breaths and should be helpful in your wet/high humidity.
I would love to see what your Miracle Grow soil looks like. I know here in Oregon they changed it, not in a good way. Mostly peat most, semps don't seem to do well in it. The old recipe for Miracle Grow worked well.

Local Miracle Grow potting soil (no water holding polymers)
Mixed with sand 60 to 70% sand. Pumice has arrived but no time to repot so far.


Typical rotted semp. Seems to have more to do with variety? Some just faded out in 3 different pots in good locations and some carry on through less sun, more soil than sand in the mix (wetter). Planning for future growth with too big a pot was also a possible problem with a few that were supposed to get big. A single semp in an 8" pot didn't work in a few cases.



Most of these look good, but not all.

Lol, rediscovered yuccas after the semps started rotting.
Agaves in pots has been a complete fail over more than a decade. Clay, mostly sand, proper sized pot, didn't matter. Too wet then too cold during the winter did every one of them in eventually. A really cold winter a few years ago with highs below freezing for 4 days in a row took care of the last of the Agave.

Matt, the offsets in the pot in photo #2 look healthy. Photo 3 shows many happy semps