Self seeded coriander

As my spuds have been so slow to get going I have to hand weed them where they would normally have smothered the weeds by now. I was pleased to notice, however that many of them are coriander seedlings from last years plants which I let go to seed. So I am going to let them get on with it as a sort of catch crop.
With that in mind I am thinking of having a permanent coriander bed somewhere with the intention of letting them go to seed and come up again each year. I'm amazed that they don't appear to have been killed by the cold winter / spring.

Coriander is usually described as hardy (although needless to say not everyone agrees, and there are different varieties of it.)

There are many quite tender plants whose seeds are much more frost-hardy than the plants are, as anyone who has cold-composted tomatoes and cucurbit seeds will testify!