User blog comment:Joe333red/The NeoMH Lab/@comment-5028662-20130106145134/@comment-4212769-20130106230104

Actually the Tundra is only at the Polar Circle and Tundras normally have temperature over 0°C. It's far from being similar to the Antarctica as it is inside the Polar Circle.

It can actually rise to an monthly average of +6° to +10°C (From the German Wikipedia page because the English one didn't give the temperature). So plants can easily grow in summer.