Understanding Sun Exposure: Full Sun, Partial Shade, and Full Shade Definitions

Plant tags often specify light requirements like "full sun" or "partial shade," but what do these terms actually mean in terms of hours? The answer varies significantly by geographic region because sunlight intensity differs dramatically across landscapes.

Regional Sunlight Guidelines

Full Sun

Coastal areas: Unfiltered sunshine for 6 or more hours per day
Mountain regions: Unfiltered sunshine from morning to night
All other areas: Unfiltered sunshine for 8 or more hours

Partial Sun / Partial Shade

Coastal areas: All-day sunshine filtered through high pine or hardwood (oak, maple, poplar) foliage, OR 3 hours of direct morning sunshine (sunrise to noon) followed by shade
Mountain regions: Five hours of direct morning sunshine (sunrise to noon) followed by shade
All other areas: Direct sunshine for part of the day, or dappled light (as under high pine trees) all day

Full Shade

Coastal areas: All-day shade under low evergreen trees (live oak, magnolia)
Mountain regions: Occasional direct sunshine during the day or dappled shade under low deciduous trees (dogwood, redbud, crabapple)
All other areas: Dappled shade (as under low and high hardwoods) all day

Remember that afternoon sun is more intense than morning sun in any location. When evaluating a planting site, consider both the duration and the quality of light throughout the day.