Today is the longest day of the year!! June 21st is the Summer Solstice with almost 15 hours of sunlight. Take advantage of this celestial phenomenon by making a summer sun map - a simple tool you can use to determine if your plants are getting the sun they need.
To make a sun map you will need a piece of paper, a pencil with an eraser, 2 colored pencils, and a sunny day; often the most challenging component if you’re a coastal gardener like me.
Begin by making a sketch of your garden including large trees, fences, and other significant markers. Starting at sunup, use one colored pencil to draw a line that defines the shaded areas in your yard. Set a timer and on each hour, make a new line to update the shade’s position. When the noon sun begins to decline, change colored pencils and continue drawing hourly lines until sundown. At the end of the day, you’ll have a sun map that shows the Sun’s start times in one color and end times in another. From these two times, you can calculate the total hours of direct sunlight in any given part of the yard.
It’s best to make a second sun map in the winter. Even a seasoned gardener will be surprised at the differences in light exposure that these two maps can reveal.
At our bay area latitude, our winters have 35% less daylight than our summers. On the shortest day of the year, the winter solstice on December 20th, we receive approximately 9.5 hours of daylight. The Sun Surveyor Lite app and the web-based Sun Calc are both free and fun tools to see exactly how much sun you get at your home on any given day of the year.
Like hours of daylight, shadows will also fluctuate with the seasons. A change in the angle of the sun causes shadow sizes to increase in the winter and shrink in the summer. Winter trees will lose their leaves and open up new areas of light, and spring plants will create new pockets of shade.
Fortune shines not on the brave gardener, but on the observant one. Use your sun map to choose plants well suited to your garden’s actual sun exposure. The right plant in the right place is key to a beautiful, thriving garden.