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ABOUT LIGHT
(Courtesy of David Liddle) |
Most plants require light for Photosynthesis but each plant has a different light requirement because of where they live in their
natural habitat. Plants react to differences in light intensity and because of this we can modify a plants look by changing the
light intensity of the cultivation area.
A plant grown in a shady area, well nourished and watered, will have intense green foliage as it requires more chloroplasts to
produce the same amount of sugar as one in bright light. The increase in light level is sometimes linked to an increase in colors
other than green. Red is a common color exhibited by plants exposed to bright light. The limiting factors to light intensity
are:
1. Heat from the light source. Plants leaves should always feel cool, even in full sun.
2. Adequate nutrition and water are essential to enable the plant to photosynthesis and cool by transpiration of water from
stomata on the leaves.
3. Container grown plants can be affected by increased root temperature.
Light is measured in a number of ways and called different units, but here we will use the imperial term foot-candles. This is the
amount of light produced by a candle at one foot in a dark space.
On a clear day the light intensity is greater than 10,000 foot-candles. The instrument used to read light is called a light meter.
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The general terms used to describe light intensity are:
FULL SUN. This is direct sunlight that is unobstructed for more than six hours a day.
PARTIAL SUN. This is about four hours of full sun a day or lightly shaded all day. 30% to 50% shade.
PARTIAL SHADE. Less than two hours of full sun a day. 75% to 80% shade.
BROKEN SHADE. No direct sun but filtered light . 90% shade.
DENSE SHADE. No direct sun at all. 100% shade, as under a solid roof.
Plants can show signs of stress if the light is not right.
Too Little Light
1. Dark green leaves with no luster.
2. Each new growth smaller than the last.
3. Plant is floppy and weak looking.
4. Plant does not bloom well.
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