I've grown them successfully indoors. The pit that you take from a mango is actually a husk that contains a large flat fava bean shaped seed inside. Cut open the husk along it's edge, being mindful not to slice into the seed inside. I used a nail clipper. It was no easy task. After cutting all along the husk, I pried it open and removed the seed, I then layed the seed flat, a 1/2 inch deep in a large pot. I covered the whole pot in a clear plastic bag and placed the pot in a sunny window. Once it sprouted I removed the plastic and begin watering just enough to maintain evenly moist soil. Good luck