Plymouth Rocks are dual purpose, ideal choice for backyard garden and intensive system. Female are good layers, with the ability to lay about 200 to 240 large brown eggs per year. Male can reach 4.5kg and the females 3kg. They are very hardy with strong immune system. Plymouth Rock hens typically start laying eggs when they are around 5 to 6 months old, or between 18 and 22 weeks of age.