Determining Window Exposure & Light Levels for Plants: Principles & Resources

Window orientation determines light quantity/quality. A full explanation requires a book, but here are core principles:

Exposure Basics (Northern Hemisphere)

• South: Most intense, longest duration (all day in winter). Best for high-light plants.
• East: Gentle morning sun (2–4 hrs). Good for medium-light, cool-loving plants.
• West: Intense afternoon sun (2–6 hrs). Hot; suits heat-tolerant high-light plants.
• North: No direct sun. Bright indirect only. Low-light plants only.

Modifiers

• Overhangs, trees, buildings reduce light.
• Tinted/low-E glass cuts 30–70% intensity + alters spectrum.
• Sheers diffuse; blinds block.
• Distance from window: light drops exponentially (inverse square law).

Artificial Light Mimicry

Track lighting with full-spectrum LEDs (4000–6500K, high CRI) can supplement. Key metrics:

• PPFD (µmol/m²/s) at canopy level.
• Daily Light Integral (DLI) for species needs.
• Distance, angle, duration programmable.

Essential Resource

University of Missouri: Light for Houseplants – Covers exposure, measurement, artificial light, plant lists.

Study this guide; then ask specific questions.