How far from the window can a plant sit? Slide it and see

A plant on a sunny windowsill and the same plant on a shelf three steps back are living in two different climates. To our eyes the room looks evenly bright. To a leaf, the light can fall away to a fraction within a metre of the glass. That is why so many plants sulk after being moved to "a nice spot" in the middle of a room.

Here is how window direction and distance from the glass decide how much light a plant really gets, and a room you can slide a plant around in to see it.

Direction sets the kind of light

For most of Europe, which lies in the northern hemisphere, the sun travels across the southern half of the sky. That gives each window a different character:

• South-facing: the brightest, with the longest stretch of direct sun. Great for cacti, succulents and other sun lovers, and too much for many leafy plants right at the glass.
• East-facing: softer direct sun in the morning, then gentle light. Kind to many foliage plants.
• West-facing: direct sun in the afternoon, when the room has already warmed up, so it can feel hot in summer.
• North-facing: little or no direct sun. The light is even and steady but dim, which suits shade-tolerant plants.

If you live in the southern hemisphere, swap north and south. Trees, balconies, neighbouring buildings and net curtains all change this picture too, so treat direction as a starting point, not a verdict.

Distance matters more than people expect

Daylight spreads out as it enters through a window and much of it lands on the nearest floor, walls and furniture. Plant-care guides agree that usable light drops quickly as you move away from the glass: a plant 30 cm from a window and one 2 m away are not in the same light category.

The University of Florida's gardening advice sorts indoor light into low, medium and high. Their ranges, converted from foot-candles, are roughly 270 to 1,100 lux for low light, 1,100 to 5,400 lux for medium, and 5,400 to 10,800 lux for high, with direct sun above that. Those are mid-day figures and only a guide, but they show how wide the gaps between the bands are. A spot that feels well lit to you may sit in the low band for a plant.

Slide the plant and see

This is a top-down plan of a room with the window on the top wall. Choose which way the window faces, pick a month, then drag the plant away from the glass, or use the slider underneath. The coloured bands show how bright it is at each distance. The model is simplified and made to show the idea, so use it to compare spots, not to predict your own room.

Seasons move the bands

Try the same window in June and in December. In winter the sun is lower, days are shorter and the sky is often grey, so every band shrinks toward the glass. A plant that was happy at 1 m in summer may sit in the low band by December. Many plants slow down in winter anyway, but a spot that is clearly too dark can leave them leggy and pale.

The reverse applies to south and west windows in summer: leaves pressed against hot glass can scorch, and a thin sheer curtain is a simple way to soften the light without moving anything.

Check your own room before you move anything

• Measure from the glass. Use a tape measure from the window pane to the plant and note the distance. Compare it with the bands above.
• Do the shadow test. At midday, hold your hand a little above the pot and look at the shadow it casts. A sharp, dark shadow means bright light, a soft but visible one means medium, and a barely visible one means low.
• Read the plant. Stretching toward the window, small pale new leaves and a soil that stays wet for weeks all hint at too little light. Bleached or crispy patches hint at too much.
• Turn the pot. A quarter turn every week or two keeps growth even when light comes from one side.

Making a dark corner work

Cosy does not need a plant in every corner, and it does not need new gear. Start with what you have: move the plant closer to the glass for the winter months, clear the sill of things that block light, and wipe the window, since dust on the glass cuts the light further. White or pale walls bounce more light than dark ones. If a corner is truly dim, a tough shade-tolerant plant there and your light-hungry ones nearer the window is a fair split. A grow light is an option, but it is not needed for most homes and not worth buying until you have tried moving the plant first.