You’ve probably visited a greenhouse in the spring or summer when the weather is warm and the sunny space is full of colorful blooms. Is anything happening in those buildings when it is cold outside?
Some greenhouses are in operation year-round, especially those used to produce plants kept indoors, such as Easter Lillies and hyacinths. Greenhouses used to grow outdoor garden plants, however, may be shut down completely in summer and stay empty for much of the winter.
Greenhouses that are out of operation in winter see activity much earlier than you might think. As early as February, growers start planting flowers from “plugs,” or small plants shipped from outside suppliers. Seed-starting begins to take place, too. Shutting down a greenhouse for summer and part of winter helps to break the disease cycle and kill any lingering insect pests.
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- Summer’s colorful hanging pots are started in greenhouses when the weather outdoors is still bitterly cold.
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- To keep young plants from getting too cold, furnaces are run in the greenhouses overnight. In extreme cold, layers of clear plastic can be spread over trays of plants to act as a “greenhouse within a greenhouse.”
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- Shorter daylight hours in the winter months mean supplemental lighting is used for part of the night.
