Greenhouse Conditions
Light

Light provides the energy necessary for plants to produce food through photosynthesis. Even though the amount of light inside your greenhouse usually depends on the amount of natural sunlight available, it's helpful to understand a bit about plants' light needs.

Plants require certain quantities of light for proper growth. Light is often measured in footcandles. A footcandle equals the amount (intensity) of light produced in a completely dark space by one candle shining on a white surface that is 1 square foot in size and 1 foot from the candle.

Most vegetable plants need at least 1,000 footcandles, but many houseplants can get by with less. Many of our houseplants originated on shady rainforest floors, so are adapted to low light levels. Taller plants tend to require more light than small, bushy ones.

In geographic areas with chronic low light or long winters, you can use fluorescent or other plant lights to supplement natural sunlight. High-intensity discharge lamps such as high-pressure sodium or metal halide are expensive but efficient.

Measuring Light Intensity

 

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