The question many customers have is “What size should my rain garden be?” The quick answer is that usually rain gardens are between 100 square feet and 300 square feet.
- Smaller than 100 square feet? It’s possible, of course, but such a small garden will have very little variety of plants.
- Large than 300 feet? Always possible, of course, but that’s a lot of digging, and becomes much more expensive at that point.
Here’s a handy way of finding out the best size for your rain garden:
- Find the “size factor” (use the data sets below) which works for your type of soil and how deep the garden is
- Multiply that by the drainage area (the size you are thinking for the rain garden).
- Your answer? If it’s more than 300 square feet, it’s recommended that you divide it into two or more rain gardens
Here’s the sets of data to use:
Rain gardens LESS THAN thirty feet from the downspout:
- 3-5 nches deep: 0.19
- 6-7 inches deep: 0.15
- 8 inches deep: 0.08
- 3-5 nches deep: 0.34
- 6-7 inches deep: 0.25
- 8 inches deep: 0.16
- 3-5 nches deep: 0.43
- 6-7 inches deep: 0.32
- 8 inches deep: 0.20
Rain gardens MORE THAN 30 feet from the downspout:
- Sandy soil? 0.03
- Silty soil? 0.06
- Clay-type soil? 0.10
We hope this blogpost helps!
Minnesota Rain Gardens
1223 Dayton Avenue
Saint Paul, MN 55104