Plant Growth & Artificial Lighting


Nothing enhances the look of any room like a houseplant. Even though plants, by nature, get their light needs from the sun outdoors, many species of flora can grow lush and green indoors. All that's needed is a basic understanding of the types of light that benefit plants the most and how to provide it artificially.

Why Light is Important to Plants

Quite simply, food comes from light. Plants generate food energy from light in a chemical reaction called photosynthesis. Molecules called chlorophyll, located in specialized structures in the leaves called chloroplasts, convert water and carbon dioxide into sugar molecules in a chemical process driven by photons from a source of light. Oxygen is released after this reaction. Any home decor that absorbs carbon dioxide and provides oxygen helps the interior environment.

What Light Plants Need

The sun sends all life on earth the full gamut of electromagnetic radiation. What we call light is only a portion of this spectrum. A smaller band in that portion, with wavelengths from around 380 to 760 nanometers, is what humans perceive visually. Plants only use two parts at both ends of the visible light spectrum, blue light and red light.

Blue Light Benefits

Plants use the light from the band's blue area to create energy that's used to build up plant structure and growth. Plants that appear leggy and with few leaves could be suffering from a lack of blue light.

Red Light Benefits

Specialized cell structures collect energy from red light to trigger hormones that initiate reproductive processes in the plant. Usually, the particular species of plant in question needs a certain minimal amount of red light exposure before it will begin flowering.

Artificial Sources of Blue and Red Light

Only having to provide two small bands of the visible light spectrum makes things much easier for the indoor gardener. Cool-white fluorescent bulbs, often found in bathrooms and other living areas, are a good source of blue light rays. The closer the plant is to the light source, the greater its exposure to these rays. Place plants within a foot of the bulb for best results. This is especially true in cases when ambient light from nearby windows isn't available. Incandescent bulbs are a good source of red wavelengths. These aren't needed in as much quantity; a ratio of three incandescent bulbs to every 10 cool-white would suffice. Know, though, that incandescent bulbs produce a lot of heat, so watch for plant damage. Alternatively, "grow lights," which give off a purple glow, produce blue and red waves.

Keywords: plant indoor light, plant artificial light, houseplant light

About this Author

Elise Cooke's first book, "Strategic Eating, The Econovore's Essential Guide" came out in 2008. The UC Davis international relations graduate's second book, winner of the 2009 Best Books USA Green Living Award, is "The Grocery Garden, How Busy People Can Grow Cheap Food." Her third book, "The Miserly Mind, 12 1/2 Secrets of the Freakishly Frugal," will be out early in 2010.