Low Light Houseplants

For years, I lived in a home with bright southern exposure. A couple of hours of direct sun every day, in addition to plenty of indirect light, allowed cacti and other succulents like Aloe vera and jade (Crassula ovata) to flourish. Light requirements caused me little concern. When the leaves of a Chinese evergreen (Aglaonema commutatum 'Red Emerald') began to bleach out from too much light, I pulled the plant back slightly from the window. If the leaves of lucky bamboo (Dracaena sanderiana) scorched, I tucked them into a corner. The dumb cane (Dieffenbachia seguine) seemed to appreciate anywhere I put it.

I moved into a ground floor abode early last spring where the sun is obstructed by a manmade canyon of tall buildings. Much of the natural light filters through windows with thick translucent glass; only fleeting rays of direct light manage to sneak in. Lower light levels forced me to become more mindful. Fortunately, while the sun doesn't shine like it used to, windows still face south.

Indirect light with much lower intensity defines my new ecosystem: high levels, but mostly medium and low. Requiring at least four hours of direct or bright indirect light every day, the sun-loving cacti and succulents were adopted into new homes. Dumb cane and lucky bamboo made the transition to the new space with little ordeal; the Chinese evergreen, however, encountered stress.

Lucky bamboo (Dracaena sanderiana) is renowned for its cane-like upright stems that, when grouped together, can be grown into contorted shapes like braids and twists. Mine grows straight up and has reached a height of more than 3 feet. Lanced-shaped leaves with sharp points can grow more than a foot in length, and their width can range from 1 to 3 inches. Not a bamboo at all, this dracaena likes partial shade but remains vibrant even in deep shade. It is native to West Africa, and as a tropical shrub, its natural habitat is forest understory. My lucky bamboo is thriving in its new home where the light it receives is more even and diffuse. With no exposure to direct sun, its leaves no longer tend to scorch, and its growth, both in height and in bushiness, has increased in low to medium light.

Dumb cane (Dieffenbachia seguine) is a tropical plant found in the latitudes that stretch from Central America to Brazil. It can soak up direct sun, two to three hours per day, but will also grow at much lower light levels. The creamy white or yellow interiors of its jungle-like leaves are contrasted against leaf margins brushed in deep green. My dieffenbachia has made the transition to lower light levels, though growth during autumn and winter has not been as vigorous. New leaves have developed deeper green margins as the creamy interiors have ebbed. As a rule, plants with darker green leaves are more suited to low-light conditions. The dark green color indicates a higher concentration of chlorophyll, essential in capturing light during photosynthesis.

I learned from a plant biologist teaching at my local community college that some plants have what scientists call "high plasticity." Such plants have evolved to adapt to dramatic changes in their environment, for instance, being able to withstand periods that fluctuate between bright sun and deep shade. A plant in the rainforest might spend much of its life in complete shade. When a limb falls from a tree, opening a space in the canopy, exposure to the sun can be potentially strong. But in time, that opening will likely close, and the plant will be returned to its former shady habitat. This ability to acclimate to sudden shifts in the environment also applies to other needs a plant has. This is why some plants are more drought-tolerant than others. My dieffenbachia is a prime example of a plant with high plasticity. New leaves, greener and less variegated, are produced in lower light conditions.

In contrast to the dieffenbachia and the lucky bamboo, the Chinese evergreen (Aglaonema commutatum 'Red Emerald') did not transition well. Over the course of only a couple of weeks, many of its leaves began to fade. The change was dramatic. Even though it is a low-light plant, it had grown accustomed to bathing in bright, indirect light. With time and a more gradual process of allowing it to adjust to different levels of illumination, the Chinese evergreen might have become accustomed to lower light, but in any case, I did not have a roomy spot or the ideal conditions to suit it. Thus, I adhered to a basic maxim of gardening, "Right Plant, Right Place." Fortunately, I was able to return the Chinese evergreen to its former home, and the new occupant was thrilled to adopt it.

While I didn't have the right place for the Chinese evergreen, I did have limited space available for a few new plants. Blessedly, many houseplants thrive in indirect light. I decided to be conservative and chose plants I knew would have the best chance of success. The snake plant (Dracaena trifasciata) has a well-known reputation as a low-light plant, one that is easy to maintain, especially because it requires minimal watering. This broadleaf evergreen from tropical West Africa grows from a rhizome to form one tight clump of leaves; they thrust out of the ground as if they were the blades of swords. When grown indoors, these leaves, with their molted horizontal bands, reach up to 4 feet high or more.

Snake plants are often placed in north-facing windows where sunlight is the most subdued. In fact, while it does well in shade, this generalist grows in a wide range of light levels. Over the course of spring and summer, situated in medium light, the snake plant I acquired has produced new leaves and grown from approximately 9 inches to a height of 17 inches.  In brighter light, it would grow much taller.

Pothos (Epipremnum aureum) is a tropical vine with heart-shaped leaves native to the western Pacific and the Solomon Islands. It covers the ground and climbs trees clinging by aerial rootlets. It is sometimes called devil's ivy. A well-known houseplant for generations, it is frequently seen scaling a sphagnum pole or cascading down from a basket hung near a window. More than a dozen varieties, hybrids, and cultivars of pothos are readily available, many of which sport variegated leaves. Then there are plants that possess similar growing requirements and are called pothos but belong to different species or genera altogether, E. pinnatum spp., for example. Most pothos prefer bright to medium indirect light. I found a pothos cultivar (E. aureum 'Neon') that is a solid chartreuse color and helps liven up a darkening space as afternoon transitions into early evening. Eventually, I might seek out E. aureum 'Jade,' which has darker leaves and fares better in lower light.

With the change of seasons, shorter days, and the angle of the sun in the winter sky becoming more acute, even less light found its way indoors. By sight, I suspected I was on the most extreme borderline of acceptable light. I felt compelled to purchase a light meter.  Relatively inexpensive, the light meter I purchased reads both foot candles and the metric measurement of lux. For gardeners in the United States, the foot-candle is the most commonly used measurement. Indeed, the reading for the snake plant measured as low as 25-foot candles in mid-morning.

County extensions, horticulturists, and even engineers vary in their recommendations of what light levels qualify as low, medium, or high, and information on the Internet can overwhelm them. However, a common baseline for low light is 100 footcandles. Depending on the plant, much lower measures of light are sometimes asserted. The light meter is a handy tool, but knowing precise light levels is only a guideline. I'm also attempting to read the plant.

The very tips of the snake plant's leaves were beginning to crinkle. Although these were only the older leaves, along with my reading of the light, I took the cue. I began augmenting the snake plant, the pothos, and a few other plants with artificial light, using LED full spectrum bulbs and gooseneck-style LED grow lights. Wavelength and artificial illumination are subjects for a more thorough investigation and discussion. Creating just the right situation for my houseplants is an ongoing endeavor. I continue to experiment, seek out fact-based information, and, most importantly, observe my plants for any signs of distress.  

Attempting to grow houseplants after changing from one environment to another has afforded me a learning opportunity. I did not truly understand the role of light until I no longer had an abundance of it. Although those sunny days are gone, I will continue to grow houseplants, but I will be more cognizant of the light requirements for every plant in my care.

When spring arrives, I'll search for the perfect calathea (Calathea spp.), a small specimen that won't outgrow the proper space I can provide. It is an incredible genus that thrives in the forest understory, perhaps a rattlesnake plant (Calathea lancifolia).