Grow Tent
Grow tents are a good way to create a controlled environment for Tulasi. They are nice because they can be placed practically anywhere, and when they are properly configured Tulasi will have optimal growing conditions. If you are not able to have a small enclosed space designated for Tulasi, then getting a grow tent could really help for over the winters. For an awesome grow tent setup you will need an small inline duct fan, humidifier, heater, light, and optionally an oscillating fan. This setup can last for many years and Tulasi Devi will grow very nicely.
To learn more check out our articles on temperature, humidity, air, and light.