Exact phrase
 Any word

ViewCart Checkout
Track Your Order
Ordering FAQ
Newsletter Archive
Visit Our Retail Store
Career Opportunities
Company History
Charley's Privacy Policy
Garden Writers
Greenhouse Warranty
Greenhouse Return Policy
Favorite Links

Charley's Greenhouse
17979 State Route 536
Mt. Vernon, WA 98273
Fax 360-873-8264

Call Center Direct Line

Retail Store Direct Line

Customer Support

Visit and like us
on Facebook

How is Light Measured?

Light is measured in a standard unit called a foot-candle (fc). A foot-candle is the equivalent amount of light that is produced by an international candle at the distance of one foot.

A lumen is the term used to measure the intensity of the light. It is the total amount of light energy given off by a light source. (As you move your plant away from the light source, the lumens striking the leaf surface will correspondingly decrease with more distance.) Foot-candles (fc) ÷ 10.76 = Lumens (lux).

The Light Meter is commonly used to measure how much light a particular plant is currently receiving. It measures in foot-candles, and it usually comes with a light chart specifying the light requirements of a wide variety of common plants.


Duration: A general rule of thumb is that 12-16 hours of natural or artificial light, or a combination of the two, are needed to promote active growth. Not enough hours of light will slow or stop plant growth.

Intensity: Intensity varies enormously from plant to plant.