Waste not want not. I've punched a few holes in the base of the containers and they've been put to good use in the greenhouse.
I've planted them up with first early peas and mange tout.
I'm thinking that if the bottom of each carton rots away I'll be able to plant the whole thing in the ground without disturbing any roots. (It's not often one hopes for the bottom to drop out of anything!)
It's bitterly cold outside, with frost on the cards for tonight, so I'm still just pottering about under cover.