How and Why to Use a Light Meter for Houseplants

Lighting is the key to healthy houseplants. Without sufficient lighting, or the right lighting,
houseplants won’t thrive.
If you want to make sure that your houseplants have enough light, the best way to do that is
with a plant light meter. A light meter enables you to accurately measure the quantity of light in
each room.
You may think that your eyes are pretty good at determining the amount of light in your home,
but once you try a light meter, you’re probably going to be surprised. You may find that your
estimations are pretty far off, which can explain why you have ailing plants.
Right light for houseplants is a must
Knowing the exact amount of light a room receives helps you make the right decisions in plant
placement. While you can use a photographer’s light meter, they are designed to be sensitive
to the same light wavelengths as the human eye, which is not what a plant “sees.”
It’s a good idea to use a plant intensity light meter. Such gadgets measure the wavelengths
used for photosynthesis and chlorophyll production.
Light meters usually show foot-candles, which is the amount of light a candle gives off in all
directions one-foot from the flame. The light intensity of a sunny summer day is approximately
10,000 foot-candles. Some meters show low, medium, or high, while others show foot-candle
measurements.
Tips for using a light meter
1 Measure the light intensity at leaf level.
2 Determine the required light requirements of what you’re growing (See list below)
3 Take readings at different times of the day from various locations near the plant and at
several distances from the light source.
Required light candle levels for common houseplants

The categories in which each of these plants appear are the lowest light in which they can
survive. Many of the plants can be grown in higher light levels.
Low-Light Plants (50 to 100 foot candles)
Arrowhead vine
Cast-iron plant
Chinese evergreen
Dracaenas, various
Peace lily
Pothos
Philodendron
Radiator plant
Sansevieria
Medium-Light Plants (100 to 300 foot-candles)
African violet
Aluminum plant
Anthurium
Coleus
Ctenanthe
Creeping fig
Croton
Dracaenas, various
Dieffenbachia
Ferns, various
Fiddle-leaf fig
Fittonia
Goldfish plant
Grape ivy
Lipstick plant
Palms, various
Peacock plant
Polka-dot plant
Prayer Plant
Purple velvet plant
Rubber tree
Schefflera
Spider plant
Split-leaf philodendron
Wandering Jew
High-Light Plants (300+ foot-candles)

Begonia
Cacti/Succulents
Citrus
Ficus benjamina
Orchids, various
Hoya
Zebra plant
Too Much Light for Houseplants or Not Enough?
Knowing if you have the right amount of lighting for your houseplants starts with taking a close
look at the plants. There are definite signs of over or under lighting. Here they are:
Signs of inadequate light for houseplants
Stretching and reaching for light
Sparse growth, with long distances between leaf sets (dense growth indicates adequate light)
Lower foliage loss (available light can only sustain top leaves)
Overall loss of vitality. Leaves may be pale and flowers may be sparse or nonexistent
Pest and disease problems
Rectify inadequate houseplant lighting problems by adding full-spectrum lighting to your home.
Signs of too much light for houseplants
Scorched leafs that are browned or bleached on the window side
Overall yellowing and thickening of new growth
Excessively compact and stunted growth
Foliage curled downward
Wilting when adequate moisture is present in the soil
Lighter than normal leaves
Rectify over-lighting conditions by moving plants away from the window or installing adjustable
shades, curtains, or blinds.
Have a lighting problem with your plants? Comment here or send an email for some tips.