Did the frost kill my tomatoes?

[ElleDubloo]

It was a bit cold this past week, and I'm wondering if this is what killed my tomato plants? I bought these two plants a couple of weeks ago in a good garden center, and planted them out on the same day, in good quality compost and manure in a new raised bed. Watered them a couple of times when it was dry. This damage occurred very suddenly - they were fine just 3 days ago. Everything else in the garden is fine, actually, including some tomato seedlings in hanging baskets that I grew from seed.

Any idea what affected these tomatoes in isolation? Is it frost (if I failed to harden them off properly) or something else?

Frost is very likely. Tomatoes don't tolerate frosts even if they have been hardened off. Hardening off helps the tolerate non- frost chilling but not actual frost. Your hanging basket ones might have been in a warmer spot so escaped if there was a frost.

I managed to protect mine from the frost only to have two plants demolished by snails once it warmed up and rained.