Las Vegas has a wonderful growing season with only the extreme heat of summer and the extreme cold of winter, each being short, standing in the way of your harvest. And, these extreme months can be compensated for by bringing plants inside or using shade covers, lights and/or heaters and greenhouses to regulate the temperature.
Starting your summer plants in the house in January can give you a headstart for putting them in the ground after the last frost. End of the February to first of April. Check here for the