The biggest mistake people make when buying houseplants is thinking about the room rather than the window. A "bright living room" with north-facing windows is dimmer for plants than a "dark hallway" with a south-facing skylight. What matters is the direction the windows face, how many there are, and how far the plant sits from the glass. Here is how to read the light levels in any room in your home.
Why direction matters more than room type
A south-facing bedroom window provides more growing light than a north-facing conservatory on a grey day. The cardinal direction the window faces determines the angle and duration of direct sunlight reaching your plants. Room type (kitchen, living room, bathroom) is largely irrelevant to light availability except insofar as it affects window placement.
The key variables are: window direction, distance of the plant from the glass, any obstructions (buildings, trees, overhangs), and the season. Two rooms labelled identical by estate agents can differ by a factor of ten in actual light delivery for plants.
Lux ranges by window direction (UK summer)
These are real-world ranges measured at window positions on clear summer days in the UK. Overcast days reduce the figures significantly, particularly for the south window positions.
- South window, on the sill: 30,000 to 80,000 lux direct sun (peak midday); 5,000 to 15,000 lux bright indirect when overcast
- South window, 1m back: 3,000 to 8,000 lux (indirect)
- South window, 2m back: 500 to 1,500 lux
- East window, on the sill: 15,000 to 35,000 lux morning direct (8 to 11am); 2,000 to 5,000 lux afternoon indirect
- West window, on the sill: 20,000 to 50,000 lux afternoon direct (2 to 6pm); 2,000 to 5,000 lux morning indirect
- North window, on the sill: 500 to 2,000 lux reflected and diffused (no direct sun in summer)
- Room centre with south windows: typically 200 to 800 lux
- Room centre with north windows: typically 50 to 200 lux, which is below the survival threshold for most plants
What this means room by room
Living room with south windows
The best plant room in the house. The sill and positions within 1m are genuinely bright. A monstera, peace lily, and most flowering plants will thrive here. The challenge is usually that people push plants back toward the centre for aesthetic reasons, where light levels drop sharply.
Living room with north windows
Bright only near the glass. ZZ plant, pothos, and snake plant work well within 50cm of the window. Beyond that distance, choose only the most shade-tolerant varieties and accept slow growth.
Kitchen with south-facing window above the sink
An excellent position, used for herbs in most homes. The combination of south orientation and close proximity (you stand at the sink at window level) makes this one of the best herb spots in the house. East kitchen windows are good for mint, coriander, and spider plants.
Bathroom
A frosted north window is one of the hardest positions in any home. Only ZZ plant and cast iron plant survive with any grace here, and even they will not grow. A bathroom with a clear east or south window is a much better proposition, especially if the humidity suits ferns and calatheas.
Bedroom
Usually the smallest room and often north or east-facing in UK terrace layouts. Snake plant and pothos handle this well and tolerate the slightly drier air. Avoid plants that need direct sun in any bedroom that does not face south or west.
Hallway
Typically receives secondary light from adjacent rooms or a fanlight above the front door. Very dim but not zero if there is a south-facing door or borrowed light from an open living room. Grow lights are the realistic answer for hallways where you want any plant to look healthy.
How distance from the window affects light
The inverse square law means light falls off rapidly with distance from the source. At 1m from a bright south window, the light is roughly 25 to 30% of the on-sill level. At 2m it may be 5 to 10% of the sill reading.
For low-light plants this is acceptable. For medium-light plants a 1m maximum distance applies. For high-light plants (cacti, citrus, most herbs) the sill itself is the only viable position. The practical implication: a plant that struggles in a room with good windows is almost always placed too far from the glass, not in the wrong room.
Reading light without a meter
Phone apps such as Lux Meter and Photone use the front camera to give approximate readings within 20 to 40% accuracy. They are useful for comparing positions rather than for precise measurement.
The shadow test is faster. Hold your hand 30cm above a white piece of paper in the proposed plant position at noon:
- Sharp, dark shadow: high light (direct or very bright indirect)
- Faint, soft shadow: medium light (bright indirect)
- No visible shadow: low light (north or deep in room)
As a rule of thumb: bright enough to read comfortably by without turning a light on is the minimum for low-light plants. If you need a lamp to read in that spot, it is too dark for most plants without supplementation.
FAQ
Can I put a plant in the centre of a large living room with south windows?
Only if the plant is a genuine low-light variety and you accept slow growth or maintenance-only survival. At 2 to 3 metres from a south window, light levels typically drop to 300 to 800 lux, which is below the growth threshold for most houseplants. Move the plant to within 1 metre of the window or choose a ZZ plant, cast iron plant, or snake plant for a deep-room position.
Why does my conservatory sometimes have struggling plants?
Conservatories are often assumed to be plant-friendly, but they can be difficult environments. In summer they can exceed 40C, which stresses most plants. In winter they can drop to near-outdoor temperatures in unheated versions. The glass roof means seasonal light variation is extreme. A temperature-controlled conservatory with blinds for summer shade is a different matter entirely.
My bedroom is north-facing but I want flowering plants. What can I do?
For flowering plants, north-facing bedrooms typically need supplemental light. A small LED grow light strip (15 to 30W full spectrum) on a timer for 12 to 14 hours per day will allow African violets, begonias, or peace lilies to bloom. Without it, non-flowering plants are the realistic choice.
Is a skylight better than a side window for plants?
For plants directly under the skylight, yes. Skylights receive light from a wider arc of sky and are not affected by buildings or trees the way wall-mounted windows are. The limitation is that you can only have plants directly beneath the skylight. Plants at the sides of the room gain little additional benefit compared to having a north window.
My flat has only north-facing windows. Is there any point in having houseplants?
Yes, with the right plants. Snake plant, ZZ plant, cast iron plant, pothos, and peace lily all survive and look healthy in north-facing flats. They will grow slowly and may not flower, but they are far from dead. The mistake is choosing plants that need south-facing light (cacti, herbs, succulents, citrus) and wondering why they fail.