Because of still having freezing nights, I've been taking trays of recently potted semps indoors at night, but get them outside during the daytime when above freezing, to get them acclimated. I have been giving them some sunshine (air is still cool, not hot here yet), but they get open shade as well from a roof overhang over my deck in this temporary arrangement. I noticed that a couple semps got a bit of sunburn on leaf tips, as with this 'Pruhonice'.



Had tea on the deck this morning and observed my potted up semps. With one exception, all plants are doing well, I'm getting to know them


Photo on the right, left to right, bottom row: the mildly sunburned Pruhonice, Positively Glowing, Silver King, top row left to right: hirta from Bulgaria (love the little aerial chicks springing from mother hens) and two pots of Thunder, such a gorgeous pink color.


A casualty, one pot with a single rosette of 'Red Beauty' looked like the whole rosette was melting. Another pot of the same cultivar with two chicking rosettes looks fine and healthy. I thought perhaps it was dessicated so I watered it, it did not perk up. Dumped out the pot, the base of the plant and main root show no signs of rot. Not sure if this new plant can be saved.




Getting to know each variety by sight, some are unique thus easy to remember the names, Kevin's 'Hot Shot' rosettes starting to open up and show start of color, and hirta from Bulgaria with those tiny aerial chicks.

When leaves start dying or melting from the bottom up, that in my experience is fatal. Disposal of the infected rosette is what I have done, right or wrong. I think it's rot but maybe not. Rot often hits the core of the semp first. This leaf progression thing may be a different pathogen, I don't know.

Where did you get your 'Thunder'? It looks awesome.

'Hot Shot' is another doozy that's never been on my radar.

Thanks Tim, I examined the melt-away rosette, the very center with tiny new leaves emerging was rotting, I bagged it for discard, will bag the soil in that one pot as well. The main caudex and roots looked fine. Do you know if there is a particular wilt or other disease that is common with semps?

Thunder is from Youngs, and it's still available:
http://youngsgardenshop.com/su...

Hot Shot is also from Youngs and available, it's crazy hairy, love it.
http://youngsgardenshop.com/su...

Love the color and leaf shape combination on that Thunder

Paleo, looking at the Sempervivum Database, 'Thunder' can take on a range of beautiful color shades. I was unaware of this particular cultivar from Ed Skrocki hybrid, but glad that I chanced upon it.
Hen and Chicks (Sempervivum 'Thunder')

Snow and fine hail this morning, just above freezing at 34F, colder than predicted. I'm leaving my 8 trays of new semps outside, as long as it stays above freezing. Need to get Mountain Crest semps transferred into pots bigger than the 2" mini pots they ship with, there's an open gap between plastic pots and coir root blocks such that they seem to dry out fast.

We'd had really warm weather here, like in the 75F during days.
The fact the coir dries fast only protects them from actual freezing damage (no water to freeze), well in some really hot summer that is not good, yeah.
Problem is they are too opened up in my opinion for freezing temps, when the leaves are compacted hard together you know they will take the cold, but water only opens them up more. Since the leaves are so puffed up with water it will be hard for them to react to the weather fast and compact together.

Interesting photos and observations in this thread.

PaleoTemp said:
Problem is they are too opened up in my opinion for freezing temps, when the leaves are compacted hard together you know they will take the cold, but water only opens them up more. Since the leaves are so puffed up with water it will be hard for them to react to the weather fast and compact together.

This would seem to mean I should not be watered until the freeze cycles pass???

Not entirely Marilyn. They can desiccate in you high desert conditions. If there is no moisture present in the containers it will not harm them to give just a sip of water close to the rosets, but not on their foliage.

The plant is not doing growth at freezing temps watering is not necessary if everything is already moist.
These plants seemed filled with water, they are opened up, some of the hirta chicks are opened up beyond (curled back). In my experience plants like that can't quickly clump up their leaves fast (ball up, so to speak) and die easier from freezing, in summer those leaves are quickly dead in full massive sun while the other leaves ball up fast to protect from the sun.
In my experience it is hard to kill a sempervivums in a soil that cannot drip any water if you squeeze it hard with your hand.
Also the roots may still have water around them even if the surface of the coir is drier.
Sometimes here hits some -15C ( 5F ) at night and I watch the weather forecast just to not water the semperviums, ahead of time with 5 days.
I mean for pots, the smaller pots are so much easier to control and adjust watering based on temperature and sunlight.

Mark, that'Red beauty" reminds of freeze damage which happened to my 'Blue Boy" this spring. look up my thread of freezing semps.

GregC said:Mark, that'Red beauty" reminds of freeze damage which happened to my 'Blue Boy" this spring. look up my thread of freezing semps.

I thought of that too GregC, but my plants have never been exposed to freezing temps ever since the orders arrived approx. 2 weeks ago, and the 2nd potted plant of 'Red Beauty' right next to the sick plant looks fine, my guess it had some sort or wilt or virus that took it down quickly. I'm watching the rest of my new plants for any signs of distress.

Paleo: what you say makes sense. All the plants I ordered came from much milder climates, and growing in greenhouses, so I know that when they arrived in our much colder climate, I carry all the trays of semps into my basement early each evening before temperatures drop to freezing. Just got our updated extended weather forecast, night time temps at or below freezing predicted for next 5 days, so I shall keep up with moving trays into the basement each night for protection.

On the other hand, I want to limit the duration of time spent indoors; with a recent 2-day long freezing ice/snow/rain event, I had to kept the trays inside for 2 days, and the rosettes opened up considerably in those two days. Having these plants outdoors in cool breezy air, sunny or cloudy, makes the rosettes turgid (firm) and they're really looking great. Once we finally get to a point where it doesn't freeze every night, they'll be moved permanently outside, and once all danger of frost is past, they'll be planted permanently in landscape beds and large planters/troughs.

Partial view of semps in one of my trays, after this morning chilly rain/snow at 34F, few degrees above freezing, high temp today is 42F, they're looking good: columns left to right, Column 1: Apple Blossom, two Honigmond below (bottom one are chicks), Column 2: Zircon, Column 3: Dream Catcher.


Closer look at the melted-away 'Red Beauty', caudex and roots showed no sign of rot, but it was rotting from inside the rosette center.

I've had some in a very sandy substrate in pots which retained very little water, they weren't watered and did excellent at freezing temperatures day and night here while overwintering. When I say fine, I mean not a single dead leaf, sort of my gauge for doing good. But I have changed the substrate because the weather got so warm and soon will be hot that water has to be retained due to major evaporation in full sun.