Here's how to keep bread fresh without plastic - use a hand made STP Goods Birds Pattern Birch Bark Bread Box A wooden home accessory is an ideal choice for those, who prefer natural and eco-friendly products. Birch bark is the bark of birch trees. The birch bark can be harvested in the spring and autumn, when the sap runs. There are only a few days during these periods, when the bark peels off by itself. At this time, the bark is elastic and can be easily removed from the tree. If done mindfully, harvesting pieces of bark will not harm birch trees.