Look where the plant will live.
Observe the position at different times of day. Is direct sunlight hitting the leaves? Is the room bright without direct sun? Does furniture or a neighbouring building block the sky? A room that feels comfortable to human eyes can still offer too little light for healthy plant growth.
Strong daylight without harsh direct sun on the leaves. A useful starting point for many plants in our shortlist.
Less intense natural light. Tolerant plants may grow more slowly. This does not mean a windowless room.
Sunlight directly reaches the leaves for part of the day. Intensity and duration vary. Acclimation matters.
Direction needs context.
Window direction means different things across hemispheres and seasons. A nearby wall, tinted glass or a deep overhang can matter more. Choose the finder’s light category from the actual position, rather than assuming every north-facing or south-facing window behaves the same.
What about a grow light?
A suitable grow light can supplement inadequate daylight. Spectrum, intensity, distance and duration all matter. Use the manufacturer’s measured data and the plant’s requirements; a bright-looking household lamp is not necessarily adequate.
A browser camera is not a calibrated light meter.
We don’t claim to measure PPFD from your camera. Automatic exposure, device sensors, lens characteristics and spectral differences make uncalibrated readings unreliable. For quantitative decisions, use an appropriate meter or validated equipment data at the intended leaf position.
Source
University of Minnesota Extension — Lighting for indoor plants and starting seeds. Reviewed 4 October 2026.