Confession time: I broke my number one gardening resolution this week. Namely, always plant shop with a list and purchase only what is on that list.

This is a trying time of the year for gardeners. I’m like a zombie hunting for brains. The seed catalogs are stacking up, filled with photographs of bright colors and mouth-watering descriptions. It is cold outdoors and weeks too early to start seeds in the greenhouse unless you are sowing geraniums (I don’t). Once winter pruning is done, there is not much to enjoy while we wait for spring. I avoid nurseries (why suffer temptation when vulnerable?) but in my rush to leave a big box store last week, I exited through the garden center. And there it sat, looking like Cousin Itt, waiting for me and my debit card. Marked down for clearance, even. It was fate. We were meant to be together.

Once home, I researched cultural conditions for my new Rhipsalis. My gardening skills stop at the back door, but this sounds like a houseplant that will withstand neglect and low light levels. The tag indicated low water usage and indirect light only. Check and check.

What exactly is a “low light” level? How does one measure light? Let me share what I learned. The human eye is efficient. We compensate in low light, which makes it harder for us to estimate conditions. An electronic light meter can be used for accuracy. To use a meter,  remove the protective lens cover, point it at the light source, and receive a reading, measured in a unit called footcandles. Plants listed for low light levels generally need 25 footcandles. High light needs are 150 footcandles or more.

If you don’t want to purchase a meter, there are several light-measuring apps for your mobile phone. I compared the results of one of these against the results of an electronic meter. The readings were not the same, but fairly close.

My preferred method does not require equipment or app. Look for shadows. If you see crisp shadows with defined edges, you are looking at high light exposure. Indistinct shadows without defined edges indicate low light levels. Keep in mind that light intensity changes with the season. An African violet that does well in a window during winter months may get crispy leaf margins or even scorched spots during the summer months in that same window.

Back to Rhipsalis. The common name is Mistletoe Cactus. It is epiphytic, a plant that grows on another plant but is not dependent upon its host for food. My specimen looks like a character from the Addams Family, with waving green tendrils that like to lean toward a light source. I was concerned to find that the individual tendrils can reach up to twenty feet in length. They are slow-growing, however, and can be maintained at a manageable size by keeping it in a small pot.