Light Meters

By Marie Hofer, HGTV.com

You're eyeballing a lovely cattleya orchid for sale while you mentally survey your living room. Surely there's enough light, you say. After all, the walls are white, the windows huge.

Easy to entertain illusion while caught in the passion to have a plant. In this case, the table you've planned as this plant's pedestal is near a dark bookcase and sofa, and a light meter would tell you there are just enough lumens there for a philodendron or a snake plant, not a light sucker like the cattleya.

Light meters measure available light using a photo cell and give readings either as simple descriptors ("low" or "medium") or in numbers of foot-candles (the amount of light one candle throws a foot away). While the foot-candle is a more precise measurement and is often mentioned in books about indoor gardening, the "low-" and "medium+" monikers may serve
your purpose just as well.

You may have to do a little searching if you want a simple light meter. Some manufacturers have made combination meters that measure pH and moisture along with light. Although handy, those models have at least one long rigid probe that makes pocketing the meter impossible. If you're measuring foot-candles, you'll want a meter that tops out at no more than 5,000 fc so you'll have more accuracy at the lower end of the scale.

Most light meters come tightly packaged in bonded plastic/cardboard sleeves. Unless you ask a salesperson to open the package in the store, you won't necessarily get a good feel for how it works, whether you can read the gauge easily or if a wildly fluctuating needle just confuses the issue. Notice also whether the meter runs on batteries or on a photovoltaic cell, which needs no batteries.

If choosing a light meter seems too much of a hassle, try the old paper trick. Hold your hand over a piece of white paper; if your hand casts a fairly sharp shadow, there's enough light for a cattleya.

Resources
PlantSmart
measures light, pH and moisture; requires a 9V battery; sold at Brookstone stores
Brookstone
Website: www.brookstone.com

Rapitest Plant Light Intensity Meter
Luster Leaf Products Inc.
Woodstock, IL
USA
Phone: 815-337-5560
E-mail: info@lusterleaf.com
Website: www.lusterleaf.com