Draw the actual plant positions
Sketch the window, sill, nearby shelves and the places where pots could stand. Mark curtains, an overhanging balcony and buildings or trees outside. A south-facing window behind a deep overhang can offer very different light from an unobstructed window with the same orientation. Put a mark at the expected height of the foliage, not merely on the floor below it. A plant beside the window frame may receive much less light than one directly in front of the glass.
Follow one ordinary day
At several times during a representative day, record whether each position receives direct sun, bright diffuse light or obvious shade. Add the weather, because a cloudy-day observation cannot describe the sunniest conditions. Note the duration of any direct beam and whether it falls on the entire plant or only a few leaves. Repeat on another day rather than making a final map from a single glance. These observations cost little and reveal useful differences across surprisingly short distances.
Measure cautiously if you use a device
A light meter or phone app can help compare locations, but readings depend on the sensor, angle and measurement units. Hold the device consistently at leaf level and use the same method each time. Do not turn one uncalibrated reading into a precise promise that a plant will flower. If using a grow light, follow its manufacturer information for placement and monitor heat and coverage. A bright-looking room to human eyes is not necessarily supplying enough useful light for sustained plant growth.
Revisit the map when the season shifts
Repeat the exercise when nearby trees leaf out, the sun's path changes or curtains are used more often. Add brief observations of new growth: stretching stems, shrinking leaves or a persistent lean can prompt a review. Move a plant gradually into stronger light and record the change so its response is interpretable. Keep the map to one page with dates in the margin. Its value lies in making placement decisions easier, not in creating a complicated spreadsheet that no longer reflects the room.
A little further reading
Match these general notes to your plant variety, climate and local conditions.
