50 days. This is one outstanding cold weather performer! North Pole is a sweet, compact, light green butterhead that can be harvested throughout the winter and early spring. In mild regions, plant right in the garden and in cooler regions, place in a cold frame. Imagine the satisfaction of serving a salad at your holiday dinner that came from your own backyard. While North Pole is quite cold hardy, it tends to bolt quickly in warm weather so plant out a few weeks before first frost.