Rain Gardens- Good For Water Quality and Wildlife

After prolonged periods of red tide in the Gulf and blue green bacteria and green slime in bays and creeks, people are wondering what they can do to solve these problems. Although one might think that these “harmful blooms” are at a scale beyond our immediate help, such is not the case. Indeed they all feed on pollution which to some degree can originate in our yards, derived from fertilizers which are carried by rainfall into aquatic habitats. There are two solutions to this which cost very little and can have a huge benefit: 1. Stop applying fertilizer to the lawn and let your yard be a natural mixture of grasses and herbs/”weeds”, many of which are used by butterflies, 2. Divert all rain runoff into basins which recharge groundwater rather than spilling directly into aquatic habitats. Such groundwater can thus be purged of many pollutants before reaching adjacent aquatic habitats.

One simple method to divert rain runoff so that it recharges groundwater is to provide swales or “rain gardens” that catch and hold rainwater until it rapidly enters groundwater. This happens quite quickly in most dry land habitats since groundwater is often several feet below the ground surface, even on islands such as Manasota Key. For example look at the photo showing the roadside swales along the front of our island yard after a heavy rain; this ponding of water disappeared within several hours. A second example is a small rain garden which I constructed by hand to receive runoff from a portion of our roof and yard.

These temporary ponds can be made into real rain gardens by planting them with species particularly beneficial to wildlife. Ideally these would be native plants but often non-invasive exotics can provide benefits which natives cannot. If you look at the photo of a dense growth of plants in our front swale you may recognize native firebush and Walter’s viburnum which attract insects and birds with their flowers and fruits. A monarch is shown drinking nectar from flowers of firebush. Native sea grapes do well in this habitat and attract birds, such as this Cape May warbler in Spring when the flowers are blooming.

I have found that the exotic macho fern provides very good ground coverage in the shade and has attracted several box turtles which live in our yard. They move among the different rain gardens and natural areas within our yard which have natural litter and good ground cover.

Planting of the beautiful exotic Hong Kong orchid tree provides winter blooms that attract butterflies; there are very few natives that bloom in winter and provide nectar. This plant is entirely non-invasive if you use the “blakeana” hybrid which is sterile ( https://hort.ifas.ufl.edu/database/documents/pdf/tree_fact_sheets/baublaa.pdf ).

So do the right thing, divert all your rain runoff water into swales or rain gardens which are planted with wildlife friendly native plants or non-invasive exotics. The environment will benefit with less pollution and the animals will thank you by frequenting your created habitats.