Due to the deal of a lifetime, I now have a number of frost-resistant pots. They are quite thick. I want to use most of them for blueberry and raspberry cultivars from Brazelberries. Can anyone speak to the ability of these pots to withstand the elements? Longevity?

Sounds like a gimmick to me.

Explain to me what frost resistant pots you are considering. Are you talk looking at fiberglass or poly, stone, cement?

Depending on what material you are getting will make a difference what you can grow in them. They all will last probably for your lifetime.

This ideas is new to me but I've begun by painting the inside, so far. Think about painting the inside of your pots with Flex Seal. The product comes in white or black and paints on easily. I have not yet tried to paint the "rubber" itself, but plan to experiment by putting Flex Seal on a broken piece of pottery and then spray-painting it with clay-color paint -- or whatever color you like. Another option is to lightly sand the Flex Seal, then coat with yogurt, and then sprinkle moss on to "age" the container. You can buy moss "milkshake" material online. Clay-color spray paint appears to be only an online product and no longer available in the two hobby chains' stores. In any event. Flex Seal on the bottom of a clay pot will protect it from freeze-sticking to a smooth deck.

Most garden stores and big box stores have them. Very thick clay-fired. Pics...

1- Part of the pot haul
2- Pots planted with blueberry & raspberry
3-Feathered friends enjoying the new pots

Okay I know what you are talking about. Those are frost not going to be durable long term for frost freeze.

By frost and freeze I mean if they are left uncovered and the inside soil is wet you will get expansion when temps hit freeze the pots bust. This I know from experience.

You can leave them outside if you cover and keep the moisture out they will last for yrs. I found the outside paint cracked and peeled I would lightly sand and paint them.

Kept dry they can last unbroken for year