Companion Planting: A Spacing Calculator

Online companion plant spacing calculator

Crop 1 Crop 2 Crop 3 Crop 4
Pure stand spacing:
Mixture crop ratio:
Plant spacing: for evenly spaced mixtures
Clump spacing: for clumped mixtures

A spacing calculator for mixed plantings

This form calculates spacing for mixed plantings, based on pure stand spacing recommendations and the ratio of crops in a mixture. Mixtures spaced according to its recommendations use the same amount of land per plant as segregated pure stands, allowing a meaningful comparison of the land-use efficiency of mixtures and pure stands. The theory behind the calculator is discussed in more detail here.

Using the spacing calculator

  1. Fill in standard spacing recommendations for up to four crops. The units (inches, centimeters, feet etc.) must be the same for each crop; calculated values will use the same units. The default values are spacings for corn and beet, in inches, from How to Grow More Vegetables (Jeavons 2006). Pure stands of corn and beets are shown in Figure 5A, spaced according to these recommendations. 
  2. Fill in the ratio in which those crops will be planted in the mixture. The default ratio is one corn plant for every three beets (1:3), illustrated in Figure 5B.
  3. Click on the button labeled 'Calculate mixture spacing.'
Monoculture spacings
Figure 5A. A square meter of corn (white circles, left) and beets (black diamonds, right), planted in monocultures using the hexagonal spacings recommended in How to Grow More Vegetables... (Jeavons 2006).
Mixed corn and beet
Figure 5B. A square meter of corn and beets, grown in mixtures with corn:beet ratios of 1:3 (left), 1:8 (center), and 1:15 (right) using plant spacings calculated by the spacing calculator. The space between corn plants is the calculated 'clump spacing' value -- the distance between repitions of the planting pattern.

The calculator performs two calculations:

  1. Plant spacing for evenly spaced mixtures.
    This is the distance between plants in a mixture, assuming regular spacing between all plants. In the default example, illustrated on the left of Figure 5B, all plants are 8.3" apart. In order for all crops to be evenly spaced, the sum of the ratio components should be a perfect square. Examples of evenly spaced two-crop mixture ratios are 1:3, 1:8, and 1:15, which add up to 4, 9 and 16, respectively (Figure 5B). Examples of evenly spaced three and four-crop mixture ratios are 1:2:6 and 1:3:6:6, which add up to 9 and 16, respectively.

  2. Clump spacing for clumped mixtures.
    It is not necessary to have an evenly-spaced planting arrangement to use the spacing calculator. A simpler method is to arrange crops in evenly spaced clusters, and use the spacing calculator to calculate the distance between clusters. For example, a gardener who desires a 1:1 ratio of corn:bean plants would use the 'clump spacing' value to space her corn, then plant a bean next to each corn plant. If corn and beans are spaced 15" and 6" apart in monoculture, then each corn-bean pair would be 16" apart in the mixture.

    A more complex clumped mixture is a native American 'Three sisters' planting, featuring mounds of corn and bean clusters between squash plants. A common crop ratio for a 'Three sisters' planting is 4:4:1 corn:bean:squash. The 'clump spacing' value recommends that mounds be spaced 36" apart if the pure stand spacings of corn, bean and squash are 15", 6", and 18", respectively. 

Web page and spacing calculator by Michael Bomford.

Last updated October 2, 2007

College of Agriculture, Food Science and Sustainable Systems