We’ve gotten very good at getting water away from our homes and into storm sewers. This is good since it protects property. We’ve also gotten very good at covering the land with impervious services, such as roofs and driveways. This is bad since it makes the issue of flooding much worse. Flooding has become the number one insurance claim in Canada and, in case you haven’t noticed, Milton is FLAT.
On the bright side, there’s a great solution. Rain gardens are shallow dish-shaped beds for flowers and shrubs, designed to capture and soak in precipitation.
On the downside, bylaws in Milton actually forbid rain gardens. I’m not sure if this is because of a fear of mosquitoes and West Nile Virus or not? In any case, this would be a false argument; of the 52 species of mosquitoes in Ontario, only two spread West Nile and these two types typically live in very small bodies of water such as poorly drained eavestroughs and discarded coffee cups. A properly designed rain garden will not hold water long enough for mosquitoes to breed, and yet the bylaw states roughly that there should be “no standing water at any time.” It’s a rule that definitely deserves updating.
The two most important things about rain gardens? They must be a minimum of 6 feet (2m), or ideally 9 feet (3m), from the foundation of a building and they should be shallow enough that the water drains within 24 to 48 hours. They should only be eight inches deep. The more quickly the soil drains, the deeper the garden can be, up to two feet, at which point it would need a fence around it, so never go that deep.
How big should they be? Most of the rain gardens I have designed are roughly 6’ x 8′, although you can certainly make them larger or smaller depending on your property.
They are BRILLIANT for biodiversity since many native plants are great for pollinators, birds and even monarchs! One of the best rain garden plants is swamp milkweed which is food for monarch caterpillars, and who doesn’t want more monarch butterflies? Swamp milkweed is one of the several varieties of milkweed that does not spread aggressively in the garden.
I say this over and over again, but no type of “solution gardening” needs to LOOK like a solution! You don’t need to sacrifice beauty to solve a problem. Whether you are practising edible gardening, drought-tolerant gardening or salt-tolerant gardening, for instance, if you follow the guidelines of mixing bold, grassy and feathery textures and focus on year-round fracture, any garden should be just as beautiful as a “standard” garden.
Some beautiful plants that are noteworthy for their tolerance of flooding include blue flag iris, potentilla, sneezeweed (DOESN’T cause allergies!), fireworks goldenrod (ALSO doesn’t cause allergies!), turtlehead, dogwoods and shrubby willows.
Rain gardens are only one of the tools in the toolbox. There are many components to a concept known as LID (low impact development), which encompasses all sorts of rain capturing techniques including rain barrels, evaporation ponds and infiltration trenches.
An evaporation pond is a typical, ornamental water garden to which the downspouts are guided. They will evaporate away about an inch of rain per day.
An infiltration trench is basically a glorified French well—a large underground chamber which can hold a lot of water and allow it to soak away. These are my least favourite forms of rain water handling since they are invisible. If you’re going to capture water, be a visible example in your community!
As far as rain barrels go, there’s one thing folks need to know. Everyone thinks that rain barrels are about capturing precipitation to water plants with. What conservation authorities and municipalities care about is that you empty the rain barrel two or three days BEFORE it rains again so that the barrel is ready to capture the next rainfall. This slows the flow of rain to our storm sewers and waterways.
Another great option is to use permeable pavers, which have engineered gaps to allow water to flow through. Instead of using screenings or crusher run as a base, they use clear gravel which has a lot of pore space. The gaps in between the stones are filled with clear travel as well, which means that weeds won’t be a problem. The beautiful permeable patio adds value to your home, and that’s not a bad thing.
To sum everything up, there are many ways to handle rain water. Rain gardens are the most ornamental. If each of us does a little bit to capture and soak in rain, this will reduce the seriousness of flooding and protect our creeks, rivers and lakes.
Sean James is Milton’s Gardener: a horticultural expert, a designer, a gardener, an ecologist and teacher. One garden at a time, Sean designs and plants eco-compatible, efficient, aesthetic, symbiotic gardens using philosophies and practices that are rooted in promoting native botanicals, edibles and responsible species.
#RainGardens #LID #Biodiversity #NativePlants #RainBarrels #InfiltrationTrenches #ConservationHalton #PermeablePavers