Rain Gardens

Rain Gardens
suggestions from Rick Mikula

As we continue to pave over paradise we constantly replace meadows with highways, cityscape and shopping malls. Unable to naturally absorb rainwater, over fifty percent of the runoff produced by these hardscapes and parking lots cause flooding and carry fertilizers, pesticides, automotive and toxic chemicals into storm drains. These drains then empty directly into our streams and ultimately into our bays and oceans. The result is heavy metal laden fish, unsafe drinking water, and polluted recreational areas that reduce the wildlife populations in general. A rain garden could help to reduce flooding, remove the pollutants and benefit an array of wildlife including our beloved butterflies.

Rain gardens are designed to collect rainwater and overflows allowing it to slowly filter through the roots of plants and soak back into the ground. This filtering action will replicate what would have occurred naturally had not we intervened in the first place

From a driveway swale, to a low area in the garden, or at the base of a downspout, rain gardens can be planted in a variety of situations. They are not meant to become standing ponds they are to act as temporary holding areas allowing the plants to do their job. When choosing the proper plants consider the amount of moisture in the area that they will be placed. Ideally a rain garden should drain at about an inch per hour. If you are stuck with more clay than soil in the area you may consider amending it a bit.

This is a list of plants that I have used for commercial applications in northeastern Pennsylvania. Many of the selected plants are also caterpillar host. With a little bit of online research or by contacting your local Extension office you will easily find selection that will be better suited for your locale and butterflies. Since your rain garden maybe installed to amend the effects from a parking lot, I also include some planting selections for the situation. Please keep in mind that these suggestions are what I used in my situation and not a magic bullet to end our water woes.
The First Choices For Swales

  1. Swamp Milkweed*      Asclepsia incarnata      – caterpillar host plant
  2. Cardinal Flower*         Lobelia cardinalis
  3. Goldenrod*                Solidago patula           – caterpillar host plant
  4. Swamp Azalea*          Rhododron viscosium – caterpillar host plant
  5. New England Aster     Aster vovae-angliae    – caterpillar host plant
  6. Joe-pye weed             Eupatorium fistulosum
  7. Fringed Sedge*          Carex crinita               – caterpillar host plant
  8. Switchgrass*              Panicum virgatum      – caterpillar host plant
  9. Vervain*                     Verbena hastate         – caterpillar host plant
  10. Ironweed*                  Vemonia noveboracensis
  11. Blue lobelia*               Lobelia siphlitica
  12. New York Aster          Aster novi-belgii           – caterpillar host plant
  13. Winterberry holly       Ilex verticillata             – caterpillar host plant

* Does well in saturated situations.

Second Choices

  1. Beebalm                      Monarda didyma
  2. Coneflower                 Echinacea pupurea
  3. Ironwood                    Carpinus caroliniana

Shrubs

  1. Sweet pepper bush      Clethra alnifolia
  2. Blueberry (highbush)  Vaccinium corymbosum   – caterpillar host plant

Trees

  1. Tuliptree                         Liriodendron tulipifera     – caterpillar host plant
  2. Magnolia, sweetbay          Magnolia virginiana
  3. Serviceberry (downy)        Amelanchier canadensis   -caterpillar host plant
  4. Serviceberry (shadbush)    Amelanchier canadensis   -caterpillar host plant
  5. Choke Berry (red)             Aronia arbutifolia
  6. Choke Berry (black)          Aronia melancarpa
  7. Ash (black)*                   Fraxinus nigra                 -caterpillar host plant
  8. Ash (green)                    Fraxinus pennsylvanica     -caterpillar host plant

 

SUGGESTED BUTTERFLY PLANTINGS FOR PARKING LOTS

PERENNIALS:

  1. Lupine – late spring to early summer
  2. Coreopsis – all summer
  3. Butterfly bush (buddleia) – mid-summer to fall
  4. Butterfly weed – summer through fall
  5. Asters – late summer to fall
  6. Thistles – late spring through fall
  7. Bee Balm  -Bergamot – summer through fall
  8. Purple coneflower – late summer into fall
  9. Salvia – summer into fall
  10. Shasta daisy – summer
  11. Lavender – summer
  12. Phlox  – all summer
  13. Yarrow – mid to late summer
  14. Hollyhock – summer
  15. Black-eyed Susan – summer to fall
  16. Trumpet Vine

BUDDLEIA

Butterfly Bush would be great for the parking lot. These would be the best choices;

There are hundreds of different species of Buddleia from around the World…some temperate and some tender.  “Butterfly bush” are all varieties of Buddleia davidii, that generally come from mountainous regions and do well in rocky dry conditions if they receive plenty of rainfall.

Buddleia japonica
Sunny dry soils with a long flowering period July/October Purple flowers in familiar hanging position.
Very hardy…down to –5F

Buddleia alternifolia
Small leaves and long drooping flower panicles in May/June. Good in dry conditions.
Hardy to –5F

Buddleia “Lochinch”
Hybrid between B.fallowiana & B. davidii, the benefits are a compact shrub with increased hardiness.  Flowers August/September.
Hardy to 5F

Buddleia nivea
Comes from the Himalayan mountains, a narrow flower spike. Tolerates dry conditions well.  Flowers July/August.
Hardy to 5F