Indoor Plant Light Checker

Not sure whether your plant is getting enough daylight? Use this quick checker to estimate whether its position is likely to be too dim, workable or bright enough based on your window, distance, obstructions and plant type.

This is a practical estimate, not a lux or PPFD measurement.






How the light checker works

This tool combines four practical clues: window direction, distance from the glass, anything blocking the daylight, and the season. It then compares that estimate with the broad light needs of the plant type you choose.

The result is intentionally conservative. Indoor light changes throughout the day and across the year, and two rooms with the same window direction can still be very different because of trees, nearby buildings, curtains, glass and room depth.

Why window direction matters

South- and west-facing aspects generally receive stronger or longer periods of sun than north-facing positions, while east-facing windows usually receive gentler morning light. The Royal Horticultural Society also notes that indoor light changes with the seasons and that winter sunlight is weaker.

Distance matters just as much. A position several metres back from a bright window can be much darker than the windowsill itself, even when the room feels bright to you.

What to do if the result says your spot is too dim

  1. Move the plant closer to the brightest suitable window.
  2. Open curtains or blinds during daylight hours where practical.
  3. Check whether nearby plants, furniture, trees or buildings are blocking useful light.
  4. Reassess in winter, when UK daylight is weaker and shorter.
  5. If natural light is still inadequate, use a proper horticultural grow light rather than relying on ordinary room bulbs.

For a deeper setup guide, see Indoor Plant Grow Light Guide or compare options in Best Lights for Indoor Gardening.

Important limitations

This checker estimates likely conditions; it does not measure lux, PPFD or daily light integral. Species and cultivars also vary. If a valuable or light-sensitive plant is struggling, use the result as a starting point and confirm the plant’s own requirements.

Leaf response still matters. Weak, stretched or pale growth can indicate insufficient light, while bleaching or scorching may indicate that a plant is receiving more direct sun than it tolerates.