Journal/Care Basics · 6 min read
How Much Light Does Your Houseplant Actually Need?
Learn to measure indoor light in real numbers — foot-candles and lux — and match every houseplant to the right window in your home.
Quick answer
Most houseplants want 400–800 foot-candles (roughly 4,000–8,000 lux) of bright indirect light, which is typically within 1–2 metres of a bright east or south window. Succulents and cacti want 1,000+ fc; low-light plants like ZZ or pothos manage down to 100 fc.
"Bright indirect light" is the most abused phrase in houseplant care. It sounds specific and means nothing. Here's how to actually measure the light in your home and match plants to it.
How much light is 'bright indirect', really?
Indoor light is measured in foot-candles (fc) or lux (1 fc ≈ 10.76 lux). A bright, cloudless day outside is around 10,000 fc. Indoors, even a metre from a south window rarely exceeds 800 fc. That's why plants that 'love bright light' outdoors are still happy on your windowsill.
Measure without buying a meter
Hold your hand a foot above a sheet of white paper on a sunny afternoon. A crisp, hard-edged shadow = direct sun (1,500+ fc). A soft-edged but clearly defined shadow = bright indirect (400–800 fc). A blurry, barely-there shadow = medium (100–300 fc). No shadow = low (under 100 fc).
Every modern smartphone camera app can also read lux — free apps like "Lux Meter" work well enough for houseplant purposes.
Match plant to light level
Light requirements for popular houseplants
| Plant | Min light (fc) | Ideal (fc) | Best window |
|---|---|---|---|
| Succulents / cacti | 1,000 | 1,500+ | South, on the sill |
| Fiddle leaf fig | 300 | 500–800 | East, 1 m back |
| Monstera | 200 | 400–800 | East / west, 1–2 m back |
| Peace lily | 100 | 200–400 | North / interior |
| ZZ, snake, pothos | 50 | 150–400 | Anywhere with daylight |
How direction shapes intensity
In the northern hemisphere, south-facing windows deliver the most light for the longest hours. East windows offer gentle morning sun; west windows deliver harsher afternoon heat. North windows never see direct sun and cap out around 200 fc even at midday.
Signs a plant wants more (or less) light
- Leaning toward the window, long stretched stems: not enough light.
- Small new leaves compared to old ones: not enough light.
- Pale, bleached patches, especially on top of leaves: too much direct sun.
- Loss of variegation (all green): not enough light.
If in doubt, snap your plant in PlantMe and it'll match the species to your room's light conditions.
Frequently asked questions
Is grow light the same as sunlight?
For photosynthesis, yes — plants care about photon count in the 400–700 nm range, not the source. A full-spectrum LED grow light 20 cm above the canopy for 10–12 hours a day replicates a bright windowsill.
How long does a plant need to acclimate to a new light level?
Two to four weeks. Move plants gradually — a metre closer to the window every few days — to avoid sunburn or leaf drop.
Do south-facing windows work in winter?
Yes, but the sun's angle drops sharply. A plant that was in bright indirect light in July may sit in direct sun in December — check for leaf scorch and pull back if needed.
Try it yourself
Diagnose it instantly with PlantMe
Snap a photo of any plant or leaf. Get the species, the diagnosis, and a care plan in seconds.
Download on theApp StoreKeep reading
See also