Full sun, part shade, shade: how much sun does your garden get?
What full sun, part sun and shade mean in hours, how to measure the sunlight in a garden spot through the year, and how fences, walls and trees change it.
Seed packets and plant labels use three simple categories: full sun, part sun or part shade, and shade. They are about the number of hours of direct sunlight a spot gets on a typical day in the growing season, not about how bright it feels.
Why the hours change through the year
A spot that gets all-day sun in June can be in shade for most of December. Two things change:
- Day length. At 45° to 50° north, the longest day has about 15½ to 16½ hours of daylight, the shortest only about 8 to 9.
- Sun height. The noon sun is about 45° lower in December than in June. A 2 m fence that casts a 1 m shadow at noon in June casts a shadow over 5 m long in December.
That is why gardeners usually judge sun exposure for the growing season, roughly April to September in the Northern Hemisphere. The garden sunlight calculator averages the hours over exactly that period.
How obstacles block the sun
Whether a fence, wall or tree shades your spot depends on three things: its direction from the spot, its height and its distance. What counts is the angle from your spot to the top of the obstacle:
- A 2 m fence 2 m away blocks the sun up to 45° elevation in its direction.
- The same fence 6 m away blocks it only up to about 18°.
At mid-latitudes an obstacle to the south matters most, because that is where the sun is at midday. Obstacles to the north hardly matter in the Northern Hemisphere. Obstacles to the east and west cut off morning or evening sun, which matters most in summer, when the sun rises and sets far to the north-east and north-west.
How to measure your garden
- Watch and note. On a clear day, check your spot every hour and note whether it is in sun or shade. Do it again in a different season. It is slow but reliable.
- Calculate. In the garden sunlight calculator, enter your location and add each obstacle with its direction, distance, height and width. The tool computes the hours of direct sun for every month, shows when during the day the spot is sunny, and gives the classification for the growing season. The 3D view shows the shadows moving through the day.
What grows where
- Full sun (6+ hours): tomatoes, peppers, squash, beans, most herbs (basil, rosemary, thyme), lavender, roses, most fruit trees, sunflowers.
- Part sun / part shade (3 to 6 hours): lettuce, spinach, chard, peas, radishes, parsley, mint, hydrangeas, many perennials and shrubs.
- Shade (under 3 hours): ferns, hostas, astilbes, woodland plants, some ground covers, and moss.
Frequently asked questions
How many hours is full sun?
Full sun usually means at least six hours of direct sunlight per day during the growing season. Fruiting vegetables such as tomatoes, peppers and squash do best with eight or more.
What is the difference between part sun and part shade?
Both mean about three to six hours of direct sun. Part sun usually suggests the upper end of that range and tolerance of some afternoon sun; part shade suggests the lower end and a preference for protection from hot afternoon sun.
Does morning or afternoon sun count the same?
The hours count the same, but afternoon sun is hotter and harsher because the air and soil have already warmed up. Many shade plants cope with morning sun but scorch in afternoon sun.
Does light through a tree count as sun?
Dappled light under a tree is not direct sun. Under a light canopy such as a birch, the effect is closer to part shade; under a dense canopy such as a beech or maple it is shade. In early spring, before leaves open, deciduous trees let much more sun through.