Sempervivum

Sempervivum.

巻絹 (まきぎぬ)

It is a seedling I bought at a nearby flower shop.
Perhaps it is Sempervivum arachnoideum that has been inflated?
近くのお花屋さんからの苗です、多分間延びした巻絹（Sempervivum arachnoideum）かな？

But, because appearance is quite large, it may be Sempervivum 'Oomakiginu'.
でもかなり、ガタイが大きいので、大巻絹（Sempervivum 'Oomakiginu' ）かも？

The point to be aware of in the cultivation of sempervivum native to European mountains is that it is weak in the summer.
It is strong against cold.巻絹はヨーロッパの山地が原産なので、栽培は、寒さには強いけれど、暖地の夏は苦手です。

From autumn when the temperature in the night falls, please raise it against the sun.
It will be covered with a pure white silk thread.
夜の気温が下がる秋からは、日に当てて育てると、その名の通り、真っ白く絹糸を引いたような姿に変身するはずです。

If you succeed in nursery seedlings, you will get lots of stolons (runners) and it will increase often.
あと、調子よく育つと、多くのランナーを出して、よく増えます。