Projects: Supplemental Indoor Light for Carnivores, For Work and Home

Thoughts during ongoing COVID-19 self-quarantine: sooner or later, no matter what happens with a vaccine or other long term solution, we’re all going back to something we’ll collectively call “normal”. Whether we continue to shelter-in-place or start to go out, one absolute is that a need for green will only become more intense. Sure, we’re in the middle of spring in the Northern Hemisphere, but what happens in autumn and winter, or summer in lower latitudes when the heat becomes too oppressive to stay outside for long? What about the need for green for those working night shifts, where they’d like to have a flora break outside of normal daylight hours? And what about those going back to desk jobs, where the only time they see outside is when they arrive and when they leave?

Well, the good news is that while not all carnivorous plants do well indoors, some do. Trying to raise Venus flytraps or North American pitcher plants indoors is folly: besides their need for a winter dormancy, they require more light than is practical for anyone not running a cannabis grow room. Many tropical species do rather well under consistent room temperature, though, but the biggest issue indoors is with light. Most office buildings constructed after 1990 have window treatments intended to minimize light input, especially in warmer areas, and the typical office lights in those offices work for only the most shade-loving plants such as spathophyllums and philodendrons. Carnivores need considerably more light output, and until very recently, that sort of light output both generated considerably more heat than was acceptable and used too much power to do so. For the last five years, though, the humble LED light bulb offers a perfect solution.

To start, you’ll need a classic desk lamp. These are available new, used, and antique, with all sorts of features with the new lamps such as USB plugs for charging small electronic devices and additional three-prong plugs for devinces requiring more power. (Should you have permission and/or interest, these plugs facilitate setting up webcams to show off your plant at any time, but that’s up to you.) The only absolute is that the lamp has to have a standard screw light socket: everything else depends upon circumstances.

Now, a lot of proprietary full-spectrum lights are available both for plants and for such hobbies as needlepoint or model-building, and the light fixtures themselves are often available for really reasonable prices, both new and used. The catch is that the bulbs are most often fluorescent, and they aren’t designed for running every day for hours at a time. The overwhelming majority of fluorescent fixtures, either tube or compact fluorescent, have a distinctive drop in light output after a few months: they still appear to be nice and bright to human eyes six months later, but they’ve usually decreased their light output by 50 percent or more, and that keeps dropping as the months go by. Three years after installing one, the light produced by a typical fluorescent bulb will be suitable for growing ferns, fungi, and not much else. Those daylight and full-spectrum fluorescent lights are also exceedingly expensive to replace, with some having replacement bulbs that are so expensive that buying a whole new lamp is often a cheaper option. These lamps also have proprietary sockets that prevent you from installing other bulbs or tubes, and the most practical option is getting one of the lamps that accepts screw-type bulbs that’s been standard since Thomas Edison’s day.

No, the secret is going with LED bulbs. At the beginning of the last decade, before the mass manufacture of white Light Emitting Diodes, your standard plant lights were those red and blue combos for indoor gardening and Sticking It To The Man. At that time, the idea was that daylight produced a specific ratio of red photons to blue photons: red photons have a shorter wavelength and therefore less energy but sunlight produces so many more, and blue photons are more energetic but much less common. Chlorophyll molecules can use the energy from both red and blue photons, and the mass production of blue LEDs in the early 2000s meant that LEDs could be used for high-intensity plant grow lights for the first time. You won’t need anything that specific unless you really like the look, and standard LED light bulbs are both considerably cheaper and easier to obtain.

Now the other thing to consider is the output. LEDs have the advantages of not dropping in light output with time the way fluorescents do, putting out far less of their energy consumption as heat, and having a much longer practical lifespan. Running for 12 hours a day on average, a typical LED bulb will last upwards of five years before finally expiring, as opposed to six months before fluorescents need to be replaced. In a workplace or home desk environment, white LED bulbs make a lot more sense.

From there, it’s a matter of looking for light output. For the most part, LEDs come in full-spectrum, warm white, and cool white options, with the full-spectrum bulbs usually costing a bit more. Aside from that, it’s whatever moves you and makes your plant look its best. The important consideration is the actual number of lumens (the standard measurement for light output) being emitted, and most bulbs are handily labeled for such. A perfect light output for small carnivorous plant containers is about 1600 lumens, but if you can’t remember that, the labels on most LED packages offer a handy alternative. Almost always in the upper right corner, those packages list the light output equivalent of an old-style incandescent bulb, and what you want to get is a 100-watt equivalent. The actual power consumption will be between 13 and 17 watts, depending upon the brand and the particular colors inherent in the light (full-spectrum LED bulbs tend toward 17 watts), but the light output will be the same. Whatever light option you want, get a 100-watt equivalent, and screw it into your desk lamp.

IMPORTANT: Go for a 100-watt equivalent LED bulb, not an actual 100-watt LED bulb. Not only is that amount of power consumption not necessary, but most desk lamps were designed for 40 to 60 watts of power consumption. While the bulb may not be throwing off the ridiculous amounts of heat that an old 100-watt incandescent bulb did, the wiring and socket can overheat and become a fire risk.

LED bulbs produce less heat than compact fluorescent bulbs and a lot less than old-style incandescent bulbs, but they’ll still generate some heat. Therefore, unless your workspace is considerably colder than most, and I’ve worked in some horrendously cold offices, set your lamp head about a handspan away from your plant and turn it on. If you want to get fancy or to make sure your plant gets light over the weekend or over vacation, consider getting a timer, analog or digital, to set the light output to match day/night hours over the year. With this setup, it’s possible to keep many species of Asian pitcher plant and tropical sundews, butterworts, and bladderworts well away from other available light sources.

A few things to consider:

  • Many offices turn off air conditioning over the weekend as a cost-saving measure, and some carnivores such as Cape sundews (Drosera capensis) have issues with temperatures going above 26 degrees C/80F. Cape sundews react to excessive heat, either from the light or from other sources, by burning back, and Asian pitcher plant leaves turn a brassy color when getting too much light. If these happen, pull back the lamp another handspan and watch to see if the situation improves.
  • Even though you and your plant may enjoy the high levels of light from your lamp, coworkers and supervisors may not, and this situation is particularly exacerbated in the ongoing nightmare of the open office. To keep stray light from annoying coworkers and control freaks alike, consider using a light shield made of cardboard, polycarbonate plastic (old political campaign banners cut to size and painted work well), or Mylar to keep the light reflecting back on the plant and not in coworker eyes.
  • In a typical work environment, you may get well-meaning coworkers or security crew who see a light on without you at the desk, and think they’re doing you a favor by turning it off, or busybodies who don’t like having it left on over the weekend. Signage can minimize a lot of this, even if it’s a sign over the light switch reading “This Light Is Running On Purpose.”
  • It may be perfectly obvious that the light is there for a carnivorous plant, but take into account roommates, coworkers, and supervisors with a phobia of reptiles or arthropods that might assume that your container is a home for a snake or insect. Again, a sign or tag stating “Nothing But Us Plants” is a good idea, as well as one reading “Please Do Not Feed Me” for those who decide they want to watch your plant feed and drop in whatever they find. If they keep it up anyway, well, at least you have a portable lamp to move your plant to home…or to work.

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