The window table behind the estimate
These are the reference points the finder uses. The first rows of each window come straight from the University of Illinois Extension; the last point of each line extends the curve further into the room and is our estimate, shown as such in the result.
| Window | Distance (ft) and foot-candles |
|---|---|
| South | 0 ft: 1,500 fc · 2 ft: 600 fc · 5 ft: 300 fc · 10 ft: 150 fc · 18 ft: 75 fc · 25 ft: 45 fc |
| East | 0 ft: 300 fc · 3 ft: 150 fc · 8 ft: 75 fc · 16 ft: 40 fc |
| West | 0 ft: 300 fc · 3 ft: 150 fc · 8 ft: 75 fc · 16 ft: 40 fc |
| North | 0 ft: 150 fc · 3 ft: 75 fc · 10 ft: 35 fc |
A sheer curtain or outdoor shade from a tree, porch or neighboring building each multiplies the estimate by 0.5, and both together by 0.25: a rough order of magnitude for factors Clemson lists among those that change indoor light, alongside the season and the color of the walls.
Our plants by the least light they accept
- Low light or more: Boston fern, Cast iron plant, Chinese evergreen, Dieffenbachia, Dracaena, Haworthia, Lucky bamboo, Parlor palm, Peace lily, Peperomia, Philodendron, Pothos, Prayer plant, Rubber plant, Snake plant, Spider plant, ZZ plant
- Medium light or more: African violet, Air plant, Alocasia, Anthurium, Areca palm, Arrowhead plant, Begonia, Bird's nest fern, Bonsai, Bromeliads, Calathea, Christmas cactus, Coleus, Cyclamen, Echeveria, English ivy, Fiddle-leaf fig, Fittonia, Hoya, Hydrangea, Maidenhair fern, Majesty palm, Money tree, Monstera, Monstera adansonii, Pilea (Chinese money plant), Poinsettia, Polka dot plant, Rhaphidophora tetrasperma, Sago palm, Schefflera, Staghorn fern, String of bananas, String of hearts, String of pearls, Succulents, Tradescantia
- Bright light or more: Aloe vera, Amaryllis, Basil, Bird of paradise, Burro's tail, Cactus, Croton, Ficus Audrey, Gardenia, Hibiscus, Jade plant, Jasmine, Kalanchoe, Lavender, Lithops, Mint, Moth orchid, Norfolk Island pine, Oxalis, Ponytail palm, Rosemary, Venus flytrap, Weeping fig, Yucca
“Survives” in the finder means the spot is within the plant's range but below its preferred level: expect slower growth, smaller leaves and a plant that dries out more slowly, so water less there. “Thrives” means the estimate reaches its preferred level. Plants marked too bright are those whose guide says to avoid direct sun.
Where the estimate goes wrong
It assumes the Northern Hemisphere, a clear window of ordinary size, and daytime light. Large picture windows, skylights, white walls and a second window in the room all push the real value up; deep eaves, tinted glass and dark walls pull it down. The Illinois Extension also points out that indoor brightness shifts with the seasons, as the sun's angle changes and as trees lose or regain their leaves, so a spot can change category between summer and winter. Check with a light meter when a plant you care about is on the line.