DaisyI said:It has to be Sempervivum - that is the only 'Hen & Chick' type succulents that would be cold hardy enough to live in your area.
All the Sempervivums mound like that with time.
I was told that some of the plants in this garden are taken into a greenhouse for the winter, but I don't know whether the moundy one is cold--hardy or not. There were other plants in that garden that even I (a succulent newbie) could identify as hens and chicks, but they were growing in a flat, spread-out form in large groups about two or three feet in diameter. No mounds for them. The moundy plant was only about one foot in diameter. What might cause one type to grow in a large flat group and this one, in contrast, to form a mound even though its growth appears to be unrestricted?
