This is normal, mine do the same every year. Though we are not in the same zone, we are not that far off. I leave mine outside all year in pots (some shallow) and MOST of the time I do not have a problem.

Here's something you can try, Herringboned 28. Take one of the accepted babies and hold it gently until it screams bloody murder. Momma hen gets anxious and then almost frantic. Then put the late-hatcher and the screaming baby in with the mother at the same time. In my experience, momma is so intent on the screamer being returned to her that she never even notices that she is getting two for one. And once it's in there... well, hens can't count. This trick is easier where larger numbers of chicks with mom. In this case, with only two accepted chicks, it might work best if you kidnap both of them. If you wear something with loose sleeves you can tuck the third chick up your sleeve so that it is less obvious to the hen what you are up to. It should be easy to release it with the one you are holding in that hand. I take no credit for this method. Someone's kid thought it up and his mother posted it on one of the forums a long time ago. I thought it was cute and clever -- and so I remembered it when I needed it last summer. Worked like a charm... and the advantage over sneaking it under at night is you don't have to be up at the crack of dawn to make sure mom isn't pecking on it. You can just hang around for a bit at a civilized hour of the day. Towards evening might be the best time... that way they will soon sleep and the little chick will have time on its side to get used to life under a momma hen.

Dear Succulent Lover: In the invaluable little book titled: 101 Essential Tips for Cacti and Succulents published by DK, it says that raised beds and sloping mounds are an ideal way to plant succulents and cacti. Choose soil that is free-draining and add even more small rocks and coarse sand to improve drainage. Hens & Chicks and all other succulents can't stand to be in any standing water. It's OK if it rains, but the moisture must drain away as fast as possible. I grow mine in troughs made of hypertufa, the troughs have large drainage holes in the bottom and I raise them above the ground with two or three bricks. This way, no water stands in contact with the roots for any length of time. Hope this helps, good luck!

There are at least two kinds of 'Hen and Chicks': Echeveria and Sempervivum, The former does not die after blooming. However, the main rosette will dessicate and die after blooming in the genus Sempervivum. The pups (chicks) will keep on living until they bloom in two-three years. You do not need to 'mess with them', but you can pluck out the dead rosettes from the clumps. Since Echeveria would not survive your winters, I presume you planted Semps. They like to be crowded, and you can grow them as a mat: Practice benign neglect, and they will thrive. Happy Growing!