Yes you need at least two for pollination. Chestnuts have both male and female parts but are not able to pollinate themselves. They  pollinate by wind. When planted they need to be protected from deer and rabbits. When I plant I use a 40x40 weed mat so a young seedling is not competing with weeds and grass and it holds ground moisture. I use a 5' tree protector tube it acts like a greenhouse in winter and condenses when it's hot outside for a little moisture. It protects the tree from deer and rabbits. Don't let my trees branch until they are out of the tube. Then branches are for the most part out of deers reach. [ATTACH=full]225820[/ATTACH]