Understanding Light Terms: Filtered vs. Partial Sun and Fluorescent Equivalents

A grower asks the difference between filtered and partial sun, and whether fluorescent lights can replicate these conditions.

Definitions

• Filtered sunlight: Light through mesh/shade cloth reducing intensity but allowing some through; for plants needing cooler temps and no direct sun.
• Partial sun: Direct morning/evening sun with midday shade (like under trees); for plants tolerating some direct sun but not intense noon UV.

Fluorescent Lighting

Cool white fluorescents produce less UV than sunlight. All carnivorous plants tolerate strong fluorescent light well. Recommended lumen ranges (at 1 foot):

• Small tropicals (many sundews, butterworts): 6,000-12,000 lumens
• Large tropicals (Nepenthes, high-light sundews): 18,000-24,000 lumens
• Full-sun plants (flytraps, Sarracenia): 25,000-50,000 lumens

Place full-sun plants outdoors whenever possible.