Understanding Plant Light: Color, Intensity & Duration

Why Add Plant Lights?

Most indoor plants originate in full sun. Homes are dimmer; household bulbs lack sufficient intensity. Supplemental lights ensure success.

Three Light Characteristics

1. Color (Spectrum)

Sun emits all colors; plants need blue (compact foliage) and red/orange (flowering). As long as intensity in these bands is adequate, source (sun or artificial) doesn’t matter.

2. Intensity

Measured in foot‑candles. Sunny day ≈ 10,000 fc; bright living room ≈ 3,500 fc. Low intensity → leggy, weak, non‑flowering plants.

3. Duration

Hours of light per day. Artificial light is lower quality, so give more hours (e.g., 16 hrs) to compensate. New research suggests darkness may not be required for metabolism.

Heat Output

Light = energy = heat.

• HID: Hottest; keep 2‑6 ft above plants.
• High‑output fluorescent: 2‑4 ft above.
• Traditional fluorescent: Coolest; 6″ from foliage safe.

Tip: More heat → lower humidity → faster drying. Water more frequently under lights.

Find your perfect plant with our Houseplant Finder.