Oats and barley were historically the principal crops in the North where wheat was hard to grow because of the colder, wetter summers and longer winters. The mountains and glens in the Scottish Highlands can be covered by a blanket of snow while the wheat growing in the South is getting out the picnic blanket in early spring. While the mid and south of Britain harvest in July, the north of Scotland often harvests at the end of September. In some areas with a more changeable climate, different crops would even be sown together on the same land to ensure a harvest. If they all grew, the bakes would be made with a multi-cereal mix, but if the weather was wet, only the hardier grains would survive. Peas and beans would also be added to bakes when grain was expensive.