Have you noticed that produce has become more expensive in supermarkets lately? One reason is the cost of transporting fruits and vegetables from the southern hemisphere, another is unfavorable recent weather in California, a major supplier of produce, and a third is a decreased number of migrant workers available for harvests. If you’re a greenhouse owner, however, you have another option besides paying supermarket prices. You can grow your own completely organic fruits and vegetables year-round with just a little effort. I grow lettuce in my Rhode Island greenhouse from September until May, when outdoor growing can start again. I also grow tomatoes from May until February simply by providing some heat and LED lighting as the days grow cooler and shorter. In addition, I have lemons, limes, oranges, and other fruits growing in my greenhouse throughout the winter months.
What does it take to grow organic produce in a greenhouse? First, you need somewhere to start the plants. I use a germination chamber, which is just a fancy name for something that can be very simple. My setup has four fluorescent shop lights, each with a warm-white and a cool-white tube, suspended over shallow trays of potting soil. As the seeds in the trays germinate and the plants begin to grow, I raise the height of the lights so they remain positioned 2”-3” above the leaves.
As soon as plants such as tomatoes and peppers have two true leaves, they can be moved from starting trays into 4-inch pots. Now is also the time they can be taken out from under artificial lighting and placed on shelves in the greenhouse that get the proper amount of natural light.
As growth continues, just keep increasing the pot size or put the plants into greenhouse beds. In a large enough container, greenhouse tomatoes can easily reach 12’ in height and will keep yielding fruit right into winter. However, tomatoes grown in pots outdoors can be moved (very carefully) into the greenhouse, but I have found that they seem to pick up bugs when outside. When they get moved into the greenhouse, the bugs come in with them.
Indeterminate types of tomatoes (if they don’t get diseased) will even begin to set fruit again the following year. In fact, I have a three-year old pepper plant that fades a little in winter but comes right back in spring to produce even more peppers. With he addition of LED lights you can grow tomatoes, peppers eggplants and tropical herbs almost year-round in a heated greenhouse.