Please help! I have a few tubers that were delayed in shipping and are due to arrive today (December 10th).
I'm in zone 5b and we have a little snow on the ground now with a forecast of mid 40's for a couple more days. I can still dig a hole, as the ground hasn't fully frozen, but is it too late to plant?
If it is, should I try to plant in pots and keep them in the garage?

It is NOT too late to plant! As long as the ground is not frozen it's best to get them in the ground if you have their long term spot identified. The only way I'd pot them is if you'll have to move them within the first year or so. Peonies growth is very focused—cool soil cues root growth so getting them in the ground, even if you only have a few weeks before it freezes, is best for the growth. They'll go dormant during the cold winter then spring will wake them to a bit more root growth before it warms enough to see above ground growth. Best of luck with your new plants, peonies are the greatest!

I would plant them...

Just add a few inches of mulch after planting so it will give roots more time to grow before freezing and extra protection in winter. Remove it once the weather warms up in spring.

I would also plant them. We have one of those super mild winters here (so far). I still have violas and mums blooming outside, but I think I'll bring them in very soon. in general, if the soil is not frozen, you can plant. At least, I did it, and the bulbs planted that late always survived. But hurry up, cold weather is coming. According to our weather forecast, it is going to drop to -9C on Tuesday night. For me, it means that the ground will freeze and the pots must be brought in (if I cannot cover them).

Thanks everyone. I planted them on a balmy 45 degree December day.

Iluvponies said:Thanks everyone. I planted them on a balmy 45 degree December day.

This winter should be very mild. They will be OK