Apologia Biology: Watersheds

In another life, I taught AP Environmental Science and had 75 kids or more in an environmental club.  Believe me, I am not an environmentalist.  I believe in stewardship of God's creation, not radical environmental goals.  The club was for the kids.  They planted hundreds of trees, built raised beds, a green roof, bioswales, did a wetland enhancement, and created rain gardens.  I wrote grants to fund our projects.  One of the most successful projects (apart from the hundreds of trees) was the rain garden.  The band field flooded regularly.  We planted trees around the perimeter and installed the rain garden.  Problem solved.

Our present neighborhood is having a flooding problem.  My husband is on the HOA board; he and I have looked at the areas in the neighborhood with erosion and standing water.  I've been lobbying to install rain gardens.  I finally realized that unless people could see one in action no one would be interested in trying a garden in their back yards.  BTW, June is a terrible time to plant a garden.  Fall is the best time to plant.  Sadly, few nurseries have loads of healthy plants, shrubs, trees, or even bulbs available in October.  They stock plants in spring.  We’ll have to baby our little garden all summer.  Happily, our yard has not been professionally landscaped—especially in the back.  We bought this house three years ago; it had no landscaping.  Zero.  There was a small raised bed in the back.  Period.  Two large trees in the back shade nearly the entire yard.  We added a few shrubs, a tree, some perennials, and roses since moved in three years ago, in June.  The back yard stays wet for a week after every rain.  So, we were ready for a solution.

Our little plot is a demonstration rain garden. (Our plot has about four hours of sun.)  We bought pea gravel, play sand, top soil, mulch, humus, and plants from Walmart for under $100.  First my husband, Rob, removed the sod.  This sounds so easy; it took about an hour.  Next, he turned over the soil, meaning clay underlayer.  Afterwards, Rob spread a layer of pea gravel, then a layer of sand, and dug holes for our plants: one rhododendron, two black-eyed Susans (Rudbeckia sp.), one cone flower (Echinacea sp.), and three Caladium plants.  These plants love moist soil and can tolerate some shade.  We added Canna bulbs, too.  Evidently, Canna love water.  We have several plants I use for decoration.  Our house is in Zone 7.  We might be able to overwinter the Canna outside under six inches of mulch; other wise we'll have to dig them out of the garden.  (We keep the other Canna plants in pots we drag into our sun room over the winter.)  No, this is not a lush garden.  We plan to see how these plants grow before we add any plants or add another rain garden.  
I'll post updates on this little garden.

                                  See the red paint circle?  We planted the garden near the drain.

                       Yes, sand, top soil, mulch, humus, all from Walmart.

                                                        Here Rob is removing the sod.

                                            Here is the plot.  See the clay soil?

                                        Next is a layer of pea gravel to improve the drainage.

                                                Following the gravel is a layer of sand.

                                           Here are a few pix of the plants before adding mulch.

                                            In this last image is the drain and the garden.