Q: I’m new to gardening and was wondering if it was possible to grow tomatoes indoors year round. Our rental house has a sunroom so plants can get a lot of light there most of the year.
A: I admire your enthusiasm but it will be extremely difficult to grow full-sized tomatoes indoors. The main limiting factor is light. Tomatoes need direct, full sunshine for eight hours a day to produce fruit. Light levels outdoors are above 10,000 foot-candles but even in a bright sunroom there are less than 1000 foot-candles available.
But all is not lost! I had a lot of fun growing tomatoes indoors in an AeroGarden (Aero Garden). The company sent me a unit to evaluate and I harvested tasty cherry tomatoes for two months in winter. These devices use high intensity fluorescent bulbs to supply the light tomatoes need.