Houseplants? In reality there is no such thing. The only plants that naturally grow in your house are those that grow in the shower if you don't disinfect it frequently enough. Since the fungi that grow there are not what most of us would consider beautiful additions to our living-room decor, we should learn the needs of those non-houseplants that we try to grow in our homes.
All of the plants we attempt to grow indoors are transplanted from another environment. We will only be successful in getting plants to survive indoors if we re-create their native environments in our homes. Light, suitable temperatures, humidity, growing media, fertilizer and pest controls are all important factors to consider when attempting to grow plants indoors.In my opinion lack of light is the most serious and most difficult-to-correct problem in growing plants indoors. People don't perceive low-light situations very well because our eyes adjust to high- or low-light conditions. Even though light levels are acceptable for reading and other situations, they may be fatal to some plants. We can solve many problems by selecting the right plant for our growing conditions.
Light is measured in foot-candles, but this measurement doesn't mean much to most of us since we no longer light our homes with candles. However, the relative numbers should help us select plants that survive low-light conditions. The chart accompanying this column gives light requirements of some popular indoor plants.
If you don't know how many foot-candles of light are available, you can measure it with an adjustable camera with a light meter. Use one of the following techniques to measure the light:
The first way to measure light is to set the film-speed dial to ASA 100 and aim the camera at a sheet of matte white or paper in the proposed plant location. Get close enough to the paper so the meter sees only the white paper. Don't block the light or create a shadow. The shutter speed indicated opposite f-stop 4, reading it as a whole number, will be the approximate foot-candles of illumination measured. For example, if the f-stop registers an exposure of 1/250 second, there are about 2540 f.c. of light falling on the white sheet.
You can also set the ASA film speed at 200 and the shutter speed at 1/125 second. Focus on the white paper as above. Adjust the f-stop until a correct exposure is shown in your light meter. The table on this page will tell you how many foot-candles you have.
Many houseplant books will recommend additional plants for various light intensities as well as other ways to measure the light available.
After measuring the light available, select a plant that will tolerate the light level. Keep in mind that plants grown with lower light intensities need less water and fertilizer than those growing in higher light conditions.
In addition to the amount of light, the quality and length of exposure are important. Light quality refers to the color available. White light has all the colors of the rainbow. Plants utilize mostly blue light for photosynthesis; white and other colors are utilized to a lesser degree or in other responses. Green light is reflected by the plant leaves and is not used to any great extent.
You can supplement or replace sunlight with artificial light with some plants. In general, florescent lights are more efficient and provide a better color spectrum and less heat than incandescent light bulbs. Lights must be very close to the plants and be on for 16 hours or more each day. African violets and some foliage plants are good choices for growing under artificial lights.
The length of exposure is important to some plants. Poinsettias, kalanchoes, Christmas cactus and chrysanthemums are all short-day plants. These plants need long uninterrupted dark periods to commence flowering.
You can grow plants in poor conditions if you utilize the trick used by interiorscapers. These people create the living plant displays we enjoy in shopping malls and public buildings. Because the plants may not have ideal growing conditions they have a rotation schedule for the plants. You can get the same results in your home with pairs of plants. Grow one in a sunny location and utilize the other in a darker, less favorable spot. Then, once a month, switch the two plants. The one that has been in the sun will use its stored energy to survive while the one growing in the darker location will be able to manufacture more food and so it can survive in the lower light conditions.
In future articles we will discuss the right way to provide water, fertilizer, humidity and other growing conditions for your plants so you will have an indoor green thumb.
If you would like answers to specific houseplant or garden questions, call me Saturday morning from 7-10 a.m. on the KSL Radio Greenhouse Show. KSL is 1160 on your AM radio dial.
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(Additional information)
Measuring light
IF YOUR OPENING IS: YOU HAVE:
f2.8 32 f.c.
f4 64 f.c.
f5.6 125 f.c.
f8 250 f.c.
f11 500 f.c.
f16 1000 f.c.
f22 2000 f.c.
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(Additional information)
Plant lighting chart
LOW LIGHT MEDIUM LIGHT HIGH LIGHT
PLANTS
PLANTS
PLANTS
(50-100 footcandles) (100-200 footcandles) (Over 200 footcandles)
Pewter Plant Schefflera Nortalk Island Pine
Chinese Evergreen Grape Ivy Croton
Cast Iron Plant Dracaena Zebra Plant
Parlor Palm Rubber Plant Begonia
Tricolor Bromalaid Philadendron Spider Plant
Birdsnest
Sanseverieria Pothos African Violet
Snake Plant Syngonium Yucca
Golden Pothos Benjamin Fig False Aralia