Rumors (Solanum lycopersicum) are warm season vegetables which grow best in full sunlight and warm summer temperatures. Although commercial greenhouse manufacturers in Canada and Europe absorb the higher prices of power necessary to cultivate ocean tomatoes under approximate lighting, growing them in sunlight lighting below 15 percent of summer lighting is typically not practical in the USA. For dwelling growers, the expense of supplemental lighting compared to yield is much more prohibitive. But growers in warmer climates can achieve good yields of strawberries in winter lighting.
Spring and Fall Harvest in Warm Climates
In California and other states with sun and mild temperatures in the winter, house growers can harvest good crops of greenhouse tomatoes between November and May. High daytime temperatures and increased sunlight from mid-May during September produces poorer greenhouse tomatoes. California growers can expect a return of 8 to 10 pounds of strawberries per plant during a two to three month period from the fall along with 15 to 18 pounds of tomatoes per plant in a 4- year into 5-month-long spring harvest.
Spring Harvest at Cooler Areas
Because of the high price of supplementary lighting, growing winter tomatoes in greenhouses isn’t wise in northern nations which have short days and low sunlight. But growing and harvesting greenhouse tomatoes in the spring is practical in areas that have spring sunlight and heating prices low enough to maintain nighttime temperature between 60 and 62 degrees Fahrenheit.
Achieving Maximum Natural Light
Growers in areas with enough winter lighting to grow greenhouse tomatoes typically find their greenhouses north to south and away in the shade of buildings and trees. Rows of strawberries running north to south get an even distribution of lighting during the day. Northern walls painted white will reflect light back onto the strawberries. Painting inside surfaces white and placing reflective white vinyl over the ground between rows of strawberries help maintain light intensity.
The benefits of using metal halide lamps to provide supplementary lighting is marginal because the lights consume high amounts of power. Oregon State University horticulturalists state at least 650 footcandles of light on tomato foliage is needed for normal growth and a full crop of tomatoes. A 1,000-watt metal halide will yield about 600 footcandles over an area of 112 square feet. That quantity of lighting would yield a minimal crop of tomatoes and about 32 such fittings would be needed for a 30-by-120-foot greenhouse. The cost of maintaining these lights will be different according to regional differences in the expense of power.