It is generally not recommended to turn a stallion out with other horses. Keep stallions in their own paddock or pasture with appropriate fencing; i.e., not neighboring other horse fields (or at least separated by a 12 ft. lane), and approximately a 6 ft high fence. Consider placing an electric wire on the top rail of the fence to keep the stallion from pushing on the fence to get to horses on the other side.
Stallions are competitive and territorial for mares, land, food, etc. It is their more aggressive nature that prevents them from being good pasture partners for other horses such as geldings. And it is their ability to breed mares that makes them unsuitable pasture mates for young or mature mares. Colts and fillies will begin to reach puberty between 11 and 15 months of age and should therefore be separated to prevent unwanted pregnancy.
