Calla lilies cannot grow as a perennial in Northern New Hampshire as an outdoor plant. They cannot tolerate frost at all and will perish if exposed to cold temperatures.
Calla lilies grow best in U.S. Department of Agriculture hardiness zones 8 through 10. Northern New Hampshire is located in zones 3 and 4. USDA hardiness zones 8 through 10 only go as far north as Georgia and extend west to Texas.
People in Northern New Hampshire who want to grow calla lilies can successfully grow them as indoor plants or greenhouse plants. Also, they can grow them outside in the summer as long as they bring the bulb inside before it gets cold.