How to actually measure sunlight on your patio
Plant tags use these definitions, per UMN Extension and most major Extension publications:
- Full sun: 6+ hours of direct, unobstructed sun
- Part sun: 4-6 hours of direct sun, preferably morning
- Part shade: 3-4 hours of direct sun, or all-day dappled light through trees
- Full shade: less than 3 hours of direct sun, or all-day deep shade
To measure your patio properly: pick a sunny day in June or July, walk out at 8am, 10am, noon, 2pm, 4pm, and 6pm. Note which corners are in direct sun versus shade at each time. Add up the direct-sun hours. That number is your honest sunlight rating - not what the spot got in April when leaves weren't out, and not what it gets in October when the sun angle drops.
Direction matters more than people think. A south-facing wall with 6 hours of midday sun is brutal - many plants labeled "full sun" (hydrangea, hosta, even some roses) burn there. An east-facing spot with 6 hours of morning sun is the most forgiving location in the garden - plants get full energy without afternoon stress.
The north-facing patio with zero direct sun is the hardest spot in any garden. The plants in our "deep shade" category below are the only ones that reliably perform there. Don't fight the site - work with it.