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Planting Large Spaces

I’ve got a large space to fill in my landscape design. How many plants do I need?

While the average spacing for perennials is 12″ on center, closer spacing will allow the plants to fill in more quickly. Use the spacing listed with the plants as a general guide to the final size of the plant. Groundcovers should be spaced from 6″-12″ apart depending on the variety and how quickly you want to fill the area. The formula for determining the number of plants you need is as follows:

144″ (which is a square foot in inches) divided by (spacing in inches times spacing in inches) times (length of area in feet times width of area in feet)


You have an area 15′ x 24′ that you want to fill with Pachysandra Green Carpet getting coverage within 1 year. The spacing is listed at 10″.

  1. Multiply the spacing in inches by itself: (10 x 10) = 100
  2. Divide 144 by the result: 144 / 100 = 1.44 (plants per square foot)
  3. Multiply the length and width of the area: 15 x 24 = 360 (square footage)
  4. Multiply this result and the result from the division: 360 x 1.44 = 518.4
  5. Round up to the nearest whole number = 519 or better yet a full carrier = 522.

This is about how many plants you will need. If you are using staggered spacing, you may want to increase the amount by 15%.