If your area does snow from times to times ( or below 58 F most of cold months), then you definetly need winter protection from about Oct to April. Mango seedling will be a stronger plant than a grafted one, but a cost of not knowing when will it mature to start flower, neither what kind of mango will you have. You must have fresh seed without pulp to grow seedling. Bury it about 3-4 inches deep after clean the pulp because the pulp may inhibit seed germination. Soak it a few hours before seeding may help germination. Not all seed will sprout because depending how ripe the mango was picked, and if it has been in cold storage too long or not. It need warm and moist environment to sprout. The young seedling will not survive cold months if no protection from cold be done for the first few years. Mongo like a little bit dryness in the cold months. Plenty sun, enought water and nutrition during warm months. Thin young fruits, and do not cut flowers spike.