Rain Garden Construction
Fig 1; Residential Rain Garden
Rain gardens can be sized to handle a specific amount of runoff coming off all or some your properties hard surfaces or they can be sized based on how big of an available space you have. The amount of benefit will vary, but even the smallest bit helps. First, it is important to locate your garden where it will collect the runoff. It will need to be in the vicinity of the spaces and downspouts it will be collecting from and also set at least 10 away from structures. Other design considerations are listed below.
Residential rain gardens are typically designed to hold one inch of runoff from the contributing surface area. We would locate and estimate the square foot size of the surfaces we would want to collect water from, for example 1000 sf of roof, patio, and walks. Then we’d take the square footage measurement and divide by the 6” average raingarden pond depth. For our 1000 sf this comes out to be 167 sf area or roughly a general shape of 17’x10’.
Residential rain gardens are typically designed to hold one inch of runoff from the contributing surface area. We would locate and estimate the square foot size of the surfaces we would want to collect water from, for example 1000 sf of roof, patio, and walks. Then we’d take the square footage measurement and divide by the 6” average raingarden pond depth. For our 1000 sf this comes out to be 167 sf area or roughly a general shape of 17’x10’.
Rain Garden Design Considerations
- Located at least 10 feet from structures to avoid damaging foundations;
- Located less than 30 feet from a downspout;
- Do not locate over utilities or septic system;
- Should not be placed on slopes greater than 12%;
- Side slopes of basin should not exceed 3:1;
- If the on-site soils have low permeability, an amended soil drainage bed should be added to help with infiltration and aerate the soil;
- Placement of excess soil;
- A minimum of 3’ bottom of the excavation to seasonably high-water table in order to maintain water quality and effective hydraulic capacity;
Planting the Rain Garden
A rain garden installation is an opportunity to create a sustainable living community that will change over time and add distinct curb appeal to your landscape. The use of deep-rooted plants helps by up taking water, aerating and improving the soil condition and water intake. Additional benefits occur from, the creation of pollinator habitat, filtration of pesticides and fertilizers, aesthetic quality, and more. Plants should be selected to be placed in the wet, slope and dry (top) zones of the garden. Plants in the wet zone are water tolerating for short periods of time. Many native shrubs, grasses and forbs will work in raingardens and should be given precedence in the design for all of the above reasons.
Fig 2; Deep-rooted native plants filter water in rain gardens
There are several ways to plan and plant a raingarden with each one having some advantages depending on what you are looking for. The first method is to seed your raingarden basin using a specific mix of grasses, sedges, and forbs. This creates a more meadow like look and allows for a more diverse mix of plants while also being very cost effective. It does take a more time to establish and looks a little messy until fully established, but only recommended watering and light weeding will be necessary to maintain during that time.
The second method is to install plants that have already been started which can also give you a more manicured look if that is the aesthetic you’re looking for. This is accomplished by planting plugs, which are started plants grown in trays, only a few inches tall. The plugs would be spaced out according to size and location in the garden and more regular weeding and watering is needed in regards to maintenance. Similarly, you can plant even larger plants from quart or gallon pots. Costs rise incrementally with plant size and there is a little more upfront maintenance, but you have a more established, finished looking garden bed sooner.
Fig X; Various rain garden plant plugs. Fig X; Individual plants from pots spaced out in the rain garden.
Lastly you can plant in a hybrid combination by installing some larger plants from pots and seeding around them. This installation will give you some more instant appeal in the garden but also allow additional diversity to fill in naturally around it and some cost and maintenance flexibility.
Working with a seed and/or native plant company that specializes in ecological restoration can help you find the right mix of grasses, sedges, and forbs for your project. Additionally, they can add or recommend the right supplementation to provide specific enhancements for pollinators, bees, or songbirds depending on your preference.
Let KG Landscape Management Inc help you with your raingarden project. We have the technical expertise and installation experience to provide you with a great looking raingarden project that will function to benefit your yard for years to come.
Plymouth’s clay soil causes soggy lawns, sinking patios, and constant sump pump issues. Learn how smart drainage design fixes it for good.
Minnetonka snow removal done right means safety, efficiency, and property protection—not just plowing. Learn how true winter care works.
Plymouth drainage problems? Fix soggy clay soil and prevent foundation and patio damage with smart drain tile, grading, and discharge solutions.
Edina lawn fertilization: seasonal strategies for lasting color and health. Expert insights on timing, topdressing, and soil care.
Design a Minnetonka outdoor kitchen built for all seasons — cedar, stone, and smart drainage make year-round living effortless.
Medina lawn experts explain how healthy soil—not chemicals—creates lasting weed control through aeration, overseeding, and topdressing.
Medina drainage experts explain how French drains and drain tile systems fix clay soil water issues and prevent muddy lawns and shifting patios.
Edina patio and pool drainage: protect your investment with smart design and precision installation that keeps surfaces beautiful, safe, and stable year-round.
When Pergolas Don’t Last, There’s Always a Reason After nearly two decades of building outdoor spaces across Medina, I’ve seen what happens when pergolas aren’t designed for Minnesota’s conditions. You can spot them a mile away—posts that lean, beams that twist, and concrete pads that have heaved out of level after just a couple of winters. It’s not because homeowners cut corners intentionally. It’s usually because whoever built it didn’t account for what our climate really does to structures that aren’t anchored right. Medina’s heavy clay soil doesn’t drain well. It holds moisture, freezes solid, and then expands like a hydraulic press pushing on everything above it. When pergolas are set on surface-level post bases, that pressure has nowhere to go but up—and the whole thing moves. Even small shifts can cause joints to separate, wood to crack, and hardware to loosen. That’s how a $15,000 structure starts looking tired after a few years instead of standing straight for decades. The truth is, pergolas here aren’t just about shade or looks. They’re about structure, drainage, and how every piece ties into the patio beneath it. A pergola that stands tall through Minnesota winters is built on the same principles as a good foundation—it’s only as strong as what’s underneath it. If you live in Medina and want to enjoy your backyard without worrying about your investment warping or sagging, start with design that respects the environment it’s built in. That means thinking beyond lumber and stain colors. It means understanding soil movement, water management, and the importance of integrating your pergola with the patio below it.
Solutions for Properties in Minnetonka You can always tell a Minnetonka yard that’s fighting its slope. Water doesn’t lie, it finds the weak spots every time. I’ve walked plenty of properties where a backyard starts beautiful in June, but by September, the patio is heaving, the grass near the pool looks like a marsh, and the homeowner is wondering how it got so bad so fast. The truth is, when you’re dealing with rolling terrain and heavy clay soils like we have around Minnetonka, you can’t just move dirt and hope gravity behaves. You need a plan that manages water from the surface all the way down through the subsoil. This is what I’ll walk you through here. You’ll see what actually causes drainage issues on sloped properties, how poor planning leads to cracked patios and shifting pool decks, and the smart drainage systems that can stop those problems for good. Whether you live near Lake Minnetonka or up in the higher ridges closer to Deephaven or Woodland, understanding how your yard sheds water is the difference between a property that lasts and one that’s constantly under repair. The Real Challenge of Sloped Minnetonka Yards Minnetonka is known for its hills, lakefront properties, and mature trees, but all that beauty comes with a set of challenges below the surface. Most of the soil here is dense clay. It holds water like a sponge and drains slowly, which means after every heavy rain, that water looks for a way downhill. If it doesn’t have a proper outlet, it ends up collecting right where you don’t want it, like along your patio, at the base of a retaining wall, or near your pool deck. I see this every season: homeowners trying to solve slope problems with a quick regrade, a layer of rock, or a simple surface drain. Those things might help for a while, but they don’t address what’s really happening underground. Clay soil doesn’t just get wet—it becomes saturated, expanding and contracting with every freeze-thaw cycle. When that happens under a patio or wall, it doesn’t matter how well-built the surface looks. The ground will move, and that movement cracks stone, shifts pavers, and slowly tears apart everything on top. The other challenge with sloped lots is how water interacts with gravity. It accelerates downhill, gaining momentum as it goes. When it hits a flat area like a patio, the water loses speed but not volume, pooling instead of flowing. That’s why I tell clients that “flat spots” on a sloped property are both an opportunity and a responsibility. They’re the best spaces to create usable outdoor areas, but they have to be engineered to handle water movement. I’ve worked on plenty of Minnetonka yards where the backyard has a beautiful view but terrible grading. You can have a perfect slope on paper, but if it directs water toward your house or creates a bowl effect between structures, you’ll end up with soggy soil and standing puddles that never dry. The goal is to move water off and away while keeping the surface level enough for comfort and usability. It’s a fine balance, but when it’s done right, it completely transforms how a property functions.