Plant a rain garden
The pesticides you apply to your lawn today could end up in the Mississippi River tomorrow. It's called storm water runoff and Kyle Zenz thinks it's time we did something about that.
Zenz is a basin educator for natural resources with UW-Extension. It's her job to know about this kind of stuff and do something about it, which is why she will be leading a workshop on rain gardens on Friday and helping to build one at the South Side Neighborhood Center in La Crosse on Saturday.
Though you can conserve water by having your garden watered by rain water, there's a better reason to build a rain garden, Zenz said.
"The bigger reason behind rain gardens is helping with storm water runoff.
"All the storm water pretty much in every city runs directly into the river," she said. "When we put water down our sink, it goes through wastewater treatment."
But the water that falls on the roof of your house, out through the downspout and across your lawn picks up all sorts of pesticides and even oil when it runs across the driveway. And all that ends up in rivers and lakes.
"And it's completely untreated," Zenz said. With a properly designed rain garden, the water will stay in the garden for a couple of hours and be filtered through the garden. That natural filtering will take out much of what we don't want in our rivers and lakes, Zenz said.
"Our lawns have a capability to filtrate some water, but not as much as you get in a typical rain event," she said.
Typically, rain gardens are planted with native plants that can tolerate drought so you don't have to haul out the hose during dry times.
"There's a lot of really pretty flowers that can be put in there," Zenz said.
But rain gardens are not care-free, she said. "They do take a little bit of work. It's not going to be hassle free. You need to give it a little bit of care."
If you've seen rain gardens you think are a little unkempt, never fear, Zenz said. Your rain garden doesn't have to be filled with tall, weedy-looking plants.
"A lot of times people do put the coneflowers in there. They are gorgeous, but they are tall. The mistake is putting nothing shorter in there. You need a graduation. And have plants that bloom at different times of the year.
Planning is a big part of the rain garden."
Here are some tips from UW-Extension on rain gardens
- Rain gardens are landscaped areas planted with wild flowers and other native vegetation to replace areas of the lawn, but not usually the entire lawn. The gardens fill with a few inches of water that allows the rain to slowly filter into the ground instead of running off into storm drains. Compared to a conventional lawn, a rain garden allows about 30 percent more water to soak into the ground.
- Typically, a rain garden is used to collect runoff from the roof, so it is often built close to a downspout or in a naturally low area in the yard.
- This is a garden, not a prairie, so the focus should be on flowers, although some grasses can be uses.
- You need to maintain the garden after planting, making sure to weed out the dandelions and other weeds until the mature plants crowd them out.
- Leave the dead or dormant plants standing during the winter as they will provide seeds and shelter for the birds. In spring, cut them back or mow the stalks to allow new shoots to emerge.
- Installation of a rain garden is slightly more work than installing a comparable section of lawn, but maintenance is low once the plants mature.
Building a rain garden
- Choose a location. The rain garden should be at least 10 feet from the house so infiltrating water doesn't seep into the foundation. Don't place it over a septic system. Don't choose a part of the yard that is already slow to drain. The point of the rain garden is to encourage infiltration and slow-to-drain spots won't encourage that. It's better to build in full or partial sun. Putting it in a flatter part of the yard will make digging easier.
- Decide the size. It can be almost any size, but a typical rain garden ranges from 100 to 300 square feet.
- How deep should you dig? A typical rain garden is between 4 and 8 inches deep. If you dig it deeper than that, it might retain water for too long. Less than 4 inches deep and you will need an excessive amount of surface area to provide enough infiltration.
- What is your soil type? Sandy soils have the fastest infiltration, clay soils have the slowest and silty soils are in the middle. If you have clay soil, you'll need a larger area because the soil will take longer to absorb the water.
- Before building the rain garden, think about how it will catch water. If the water is coming from a downspout, it should flow out evenly over the garden. The rain garden needs to be as level as possible so water doesn't pool at one end and spill over before it has a chance to infiltrate.
- The rain garden will need a berm or low wall on three sides to catch the water that is coming in from the fourth side. You may need to dig a shallow swale from the downspout to the rain garden to direct the water into the garden.
Plants for the rain garden
In clay soil in full sun: Red milkweed, white false indigo, blue flag iris, smooth penstemon, prairie blazing star, wild quinine, yellow coneflower, false aster, sweet black-eyed Susan, ironweed, New England aster, stiff goldenrod and fox sedge.
In loam to sand-loam soils and full sun: Red milkweed, white false indigo, blue flag iris, smooth penstemon, nodding pink onion, prairie blazing star, wild quinine, false aster, sweet black-eyed Susan, New England aster, Ohio goldenrod and fox sedge.
In sandy soils and full sun: Red milkweed, white false indigo, blue flag iris, smooth penstemon, nodding pink onion, prairie blazingstar, wild quinine, false aster, sweet black-eyed Susan, Ironweed, New England aster, Ohio goldenrod, fox sedge.
Still not convinced that a rain garden will work for you? If you still want to garden with all the colorful and newest plants, you can still incorporate a rain garden, Zenz said.
"The rain garden can be your little experiment of plants. That's what it is for some people. It's just a little showcase. It could be a small part of your landscape. It can be as complex or as simple as you want it to be. Some people like rain gardens because this is a different type of garden to try."