Minnesota is known for its agricultural productivity, and the length of the growing season is an important factor for farmers and gardeners. The average length of the growing season in Minnesota varies, but it generally falls between May and September. If you plan on gardening, start your seed indoors, and most in the Twin Cities consider is safe to put plan in the ground Mothers day Weekend. Make sure to watch frost warnings, and gradually start bring your plants outside during the to get them hardened to the climate.