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I've left a few of the tubers in the ground just to see what happens. Do you think they might sprout at all in the spring? Or do you have to sprout the slips to get anything going with them?

If they do sprout that would give them the earliest possible start, unless we get a naughty late frost sneak in and zap them.

They are in the polytunnel so that should help a bit.

They may rot over winter but usually in hotter climates, they will just sprout naturally if you plant the tuber in warmer soil. Not so good in UK without a lot of protection.