There are few things as delicious as a fresh garden tomato. And with the help of a greenhouse, this tasty treat does not have to be seasonal. The controlled temperatures in a greenhouse make it possible to grow tomatoes year round. However, greenhouse growing is not as simple as just planting and harvesting. Tomatoes that will spend their lives in a greenhouse need special care and attention even in this protected environment.
Give your tomato seeds a good start by putting their seedling trays over heat mats. Allow your tomato seeds to grow for two to four weeks before transplanting them to 10-gallon pots (that have been disinfected with bleach) filled with fresh potting soil. Add a handful of bone meal to each tomato container to prevent calcium deficiency--a common greenhouse tomato problem.
Provide your greenhouse tomatoes with supplemental light during the winter months. High-pressure sodium lights are best for tomatoes as they stimulate flower and fruit production. Expose your tomatoes to 16 to 18 hours of artificial light per day.
Keep the temperature in your greenhouse between 60 and 90 degrees Fahrenheit. In the cold winter months, this may require some supplemental heating. If your greenhouse is not already heated, you will have to purchase a heater with the correct amount of BTUs for your greenhouse.