Every tree casts shade. The amount of shade cast depends on the size of the tree and whether it is deciduous or evergreen. To calculate shade, make a grid on the ground and find out how many hours of sun or shade each square in the grid gets each day. Knowing how much shade each area of ground gets will help you decide what kind of grass you should plant and which flowers you can grow in each area.
Estimate the height of the tree. If it is evergreen and over approximately 24 feet tall, it receives nine grid squares; anything less gets one square. If it is deciduous and over approximately 26 feet tall, the grid should be 25 squares. If the tree is under 10 feet tall, make the grid one square. Anything between 10 to 26 feet receives nine squares.
Make a grid on the grass using spray paint following the formula in step one. The tree should be in the center of the middle square. Each square should be approximately 5 feet high and wide.
Watch throughout the day, from sunrise until sunset, and write down how much shade each square gets. If a square gets less than two hours of shade a day, it is considered full sun. If it gets six hours or more of shade, it is considered shady. Anything in between two and six hours is partial sun.