Hi all,

Since July I am the proud owner of 27 varieties of sempervivum with another 15 - 20 chicks. Yes I have the bug.

My concern is winter. Do I need to cover my semps when the temperature starts getting into minus? I've been looking at various ways to cover plants, mini greenhouse and plant cover bags but I'm still not sure what to do. Any advice is appreciated.

Hi David.
Good news, no cover required. Sempervivum are alpine type plants and love winter. It is also their dormant time. All that is required is fast draining soil, so they don't sit in soggy soil. And a nice layer of fine gravel, or chicken grit, as a top dressing helps, Be sure to tuck some of it under the bottom leaves of the rosettes.

David,

I do nothing to protect them here in Oregon, which has a winter climate similar to yours. Remember these are ALPINE plants, hardy to Zone 3 for most of the species. When I lived in MA, they saw -32 F more than once; only 'Commander Hay' was sensitive to this. There are few species that resent the winter wet, chiefly those from Turkey plus the ones with heavy cilia like the the ciliosums. If you have those. you might consider putting them under a little glass or plastic cover, especially if you see them showing signs of rot. I do try to pull off dead leaves on established clumps. Many cultivars will sort of shrink back in size and recover in the spring.

Hope that helps!

Kevin

So just to clarify they won't mind being covered under snow? If so then this is great news. The more I learn about these these plants the more I love them. They are the truely hardy.

They don't mind being covered with snow. In fact the snow protects them from drying winter winds. Living in Liverpool I don't think you have to worry about drying winter winds?

I had a very similar query around this time last year Dave when I was new into sempomania. The rain was my biggest concern as it rained incessantly for months . Anyway I needn't have worried as they all came through with flying colours. The snow acts as insulation apparently ,although we had none here last winter . Free draining compost is essential and this includes removing the potting compost a lot of new semps are supplied in, as this can act like a mini sponge .

We cross posted there Lynn 😃

I love your more detailed explanation.

This from Tim four days ago illustrates my point about the potting compost.
Name: Tim Stoehr
Canby, Oregon (Zone 8b)
Image
tcstoehr
Sep 16, 2015 3:03 AM WETDST
Getting back to actual soil issues... I had my first rotter. Angry
This was I think my best looking semp which was purchased as a NOID from a nursery in Woodburn. A very robust and sizable specimen at the time.
I had noticed the lowermost leaves shriveling but it didn't seem altogether unusual. I just thought (hoped) it was the old leaves dying and making way for the new ones. And the top of the rosette seemed solid. However this morning it was noticeably worse and my optimism could no longer be sustained. I tugged at the semp and it came out of the ground without alot of resistance. The first thing I noticed was the roots appeared to have largely dissolved away.

Thumb of 2015-09-16/tcstoehr/4278a7

Pulling the rosette apart revealed rot up the central stem.

Thumb of 2015-09-16/tcstoehr/7fcddd

Digging down into the soil revealed a soggy mass of potting soil... bingo. The surrounding soil in the bed was only very slightly moist.
This semp had been purchased in a 1.5 quart pot with a moisture retentive, organic potting mix. I suppose this is fine as long as it allowed to dry out between watering. But I made the rookie mistake of planting the whole root-ball including the potting mix into a quick-draining, quick-drying, sandy loam bed. This sort of soil drained and dried alot faster than the ball of potting mix, so that mix remained consistently wetter than the surrounding soil and caused the rot to occur.
Lesson going forward is to shake off any kind of potting mix before planting, even if it stresses the roots a bit. Although I doubt the little 2" pots would pose this problem... or would they? Confused

Luckily all the chicks seem OK as they have rooted out in the sandy soil.