Peas thrive in cool weather and young plants will tolerate light frosts. Once germinated, peas adapt well to the cold, damp climate of early spring. Peas must be planted as early as possible in the spring to get a full harvest before hot summer temperatures arrive and put an end to production. In temperate zones, the saying "Plant peas by St. Patrick's Day" holds true. Otherwise, plant peas about a month prior to your frost-free date.