Most cold-hardy succulents such as Sempervivums do not get very tall. It's easier to avoid freezing by keeping low to the ground. I was surprised to see the plant I know only as Sempervivum heuffelii (unknown #3) start to rise above its surroundings. My interpretation of this is it is getting ready to flower...and then die.
Sempervivums are monocarpic, which means they die after they flower. Fortunately, this plant has produced two offsets which will carry on after the main plant croaks. It's all rather fascinating. This photo is from May 27; I will replace it with a more recent one soon as the effect has become more pronounced since then.
