The following tips will help you measure and find the information you need to calculate the final number of plants to buy before you go to your garden supply store.
For large spaces, a quick and easy way to measure distances is to pace them off. To use the pacing method, do the following. Pick a stride that is uniform and comfortable for you to take. Mark the starting point of your stride at the back of your heel and then pace off three strides. Mark the tip of your foot at the end of the third stride. Using a tape measure, measure the distance you covered and divide this distance by 3. Now you have an average measurement of one of your strides. Once you have your stride measurement you always have a handy way to estimate distances and measure spaces. You can even pace around a circle to get the circumference. Of course, if you have a large tape measure and a friend to hold the other end your measurements will be more accurate.
Using the stride that was measured pace off the length and width of an area and write it down on a small sketched map. Calculate the length and width by multiplying the number of strides taken times your personal stride measurement. This will give you the length and width of the area. After using an area formula for the shape of the space the total will be the square feet. The area measurement of a rectangle is the length times the width.
A smaller space can also be measured without a tape measure by walking heel to toe and counting the steps. Take a measurement of the sole of your work shoe and write it down in your wallet and you will always have a simple measuring tool with you. The number of steps times the measurement of your shoe equals the distance of a small line. If your shoe is less than a foot long uses a fraction for working in square feet. My work shoe is 11 inches which is 11/12=0.9 feet. Twenty steps equals 18 feet.
The other important thing to know is the spacing distance of the plants to use when planting. Different plants require a different spacing to grow properly. Planting according to the needs of the plants will save money by giving them the best conditions to survive and by purchasing the correct number of plants that are really needed. It will save on extra trips to the store and it is also possible that there won’t be any more of the plants you need when you return to the supplier the second time.
Finding the recommended spacing for a particular plant species, can be done by an online search for internet sites using the plant name, also check any information available from plant seed company sites or find it on the tags in the pots provided by the grower. There are some lists in gardening books and most landscape architect books have charts with the recommended plant spacing for the most commonly used landscape plants.
Once you find the plant spacing recommendation, it will probably be given as a small range of distances such as 6″ to 8″. To decide which spacing to use depends on your particular circumstances. If you need to have your planting area fill in quickly and you have the money to spend, use the closer spacing. If you use the farther spacing it will cost less money initially but take longer for the plants to cover the area.
Use the spacing information found to calculate the final total number of plants needed. A quick way to do this is to figure out the number of plants you would need to plant in a single line at that spacing. As an example: using a recommended space of 8″ on center, divide one foot (12″) by 8″ which equals 1.5, this means you need 1.5 plants for every foot of planting in a line. At 8″ on center your factor is 1.5 plants per foot.
Now to fill in an area (this is a squared number) take the factor of 1.5 and square it. (1.5 X 1.5 = 2.25) your new factor for area coverage at 8″ on center is the factor of 2.25 plants per sq ft.
When covering 20 sq ft at 8″ spacing you will need (factor) 2.25 X 20(sq ft) = 45 plants.