Reading the light in a north-facing room
How I learned to judge the light in a dim room, and which plants have been happy there.
The room where I spend most of my time faces north. For a while I assumed this meant I could only grow plastic plants. It turns out a north-facing room can support quite a few plants, as long as you understand how its light behaves and place things accordingly.
North light is soft, not absent
A north-facing window rarely gets direct sun, at least in the northern hemisphere. What it gets instead is steady, indirect light from the sky. It is gentle and consistent through the day, which some plants love. The catch is that it fades very quickly as you move away from the glass.
The shadow test
I do not own a light meter, so I use a simple test. At midday, I hold my hand about thirty centimetres above the spot where I want to place a plant and look at the shadow on the surface.
- A crisp, clearly defined shadow means bright light.
- A soft shadow with blurry edges means medium light.
- A faint, barely visible shadow means low light.
In my room, the windowsill gives a soft, medium shadow. One metre back from the window, the shadow is faint. Two metres back, there is almost nothing. Our eyes adjust so well that the room looks evenly lit, but the plants feel the difference enormously.
What has worked here
These have done well on or right next to the north windowsill:
- Ferns, especially the Boston fern and the bird's nest fern.
- A peace lily, which flowers less than it would in brighter light but stays lush.
- Pothos, which grows more slowly than in a brighter room but steadily.
- A cast-iron plant, which seems to grow anywhere at all.
Further back in the room, in genuinely low light, only the snake plant and the ZZ plant have stayed healthy. Even they grow very slowly there. I think of that part of the room as a place where plants can survive, rather than thrive.
What did not work
I tried a small succulent collection on the north windowsill. Within two months the plants stretched toward the glass, became pale and leggy, and leaned over. Succulents need far more light than this room can give. They now live on a friend's sunny balcony and look much happier.
A fiddle-leaf fig was also a mistake. It dropped leaves steadily until I gave it away.
Small tricks that help
- Clean the window. A dusty pane cuts more light than you would expect.
- Dust the leaves. A wipe with a damp cloth every month or so helps the plant use what light there is.
- Rotate pots a quarter-turn every week or two so they do not lean permanently toward the window.
- Use pale walls and surfaces nearby if you can; they reflect a little extra light back onto the plants.
Seasons matter
In summer the long days make even a north room fairly bright. In winter the light can drop to almost nothing on overcast days. I move the more demanding plants right up to the glass from November to February, and slightly back again in summer.
The biggest lesson was to stop choosing plants first and then finding a place for them. Now I look at the spot first, do the shadow test, and choose a plant that suits it.