Designed in urban areas to collect runoff rain and snow water from buildings, parking lots and other areas, rain gardens have sunken bowl-shaped areas that allow for water to fill up and then seep into the ground instead of running into streams, rivers and storm drains. By seeping into the ground, pollutants are filtered out before reaching underground waterways. Plants intended for rain gardens must meet a few criteria, namely that they will reach over 6 inches in height when mature, have no ground-level leaves that can lead to rot if left sit in water and can tolerate both dry and wet spells. Native plants are always the best choice for rain gardens.
Purple coneflower (Echinacea) is native to most of the United States. A very hardy plant that can withstand both dry and wet spells, purple coneflower needs plenty of sun to thrive. Purple coneflower is a prolific spreader and a natural choice for naturalized areas. With daisy-shaped flowers that bloom from mid-summer to fall, purple coneflower also provides food for butterflies, bees and hummingbirds when blooming and seeds for birds through the cold weather months.
A dainty spring flower with clover-shaped leaves that is available in an array of colors, columbine is another hardy option for rain gardens. Plant near coneflowers, as they bloom while the coneflower is growing and fade when the coneflower comes to maturity.
A number of foliage plants will thrive in a shady rain garden including lady's mantle, lady fern, sneezeweed, lavender hyssop, common rush, blue sedge and red oser dogwood. Check with your local cooperative extension office for ideas on the best native New Hampshire plants for your particular sun requirements. For the best focal interest, mix plants of various colors and textures for your personal design taste.