How to calculate number of plants needed.
First thing you need to do is to determine the square footage of the area to be planted.
Determining Square Footage of a Square or Rectangular Area
Multiply the length of the area by the width of the area.
Example: Length = 6' Width = 4' Area = 6' x 4' = 24 square feet
Determining Square Footage of a Circle
Multiply the radius of the circle by itself (The radius of a circle is the distance from the center of the circle to the outside edge of the circle.) then multiply that total by 3.14.
Example: radius of the circle = 5' 5 x 5 = 25 25 x 3.14 = 78.5 square feet
Number of Plants Needed
Now that you have the square footage of your planting area, use the chart below to find the spacing multiplier based on the spacing between plants you want. area x spacing multiplier = number of plants needed
Example: To cover an area of 24 square feet with a spacing of 6". For 6" spacing, the spacing multiplier is 4.
Multiply 4 (spacing multiplier for 6") x 24 (square feet of area) and you get 96 plants needed.