Ask Mr. Smarty Plants

I understand your soils are loam over a substrate of gravely sand and are easily erodible. You will probably want some plants that form mats of roots and go down deeply. I’m  selecting some plants that will grow in very wet to pretty dry conditions as higher levels of your bank will be drier.

Here are some of the plants that would work well for you.

Starting at water’s edge, I would plant water sedge, Carex aquatilis. This plant will grow in wet soil or standing water so can be planted just above the normal water level. It will be able to live in the water during floods.  It is used in wetland restoration and is important to wildlife. There are some other sedges that like wet soils that would also work here.

There are several grasses that will work on the slope.  One that is recommended for your location is Common Reed, Phragmites australis.  You can find more information on it in the Ornamental Grasses for Iowa. This plant is often used for erosion control and is a beautiful plant. But it may become so dense that you will not be able to access the bank. And it may overgrow everything else and become a monoculture.

Another grass that I love is Indian Grass, Sorghastrum nutans. It has bright green blades and then makes a bronze seed head during the summer. It is a clumping grass but will not grow nearly as densely as common reed.  But the roots of grasses grow very long, sometimes forming up to one and a half times the mass of the plant and will help to hold the soil and subsoil on your bank. This grass responds well to both flooding and burning so will grow on most parts of your slope.

Prairie dropseed, Sporobolus heterolepis is another possibility for the highest part of your slope.  It prefers dry sandy soil, but if your loam drains enough, it may also grow there.  Among its best features are its relatively small size, beautiful airy seed heads, fall golden brown color and the ability to stand up in snow and still be a landscape feature in the winter.

Canada wild rye, Elymus canadensis might also be a good choice.  You might want to plant it first as it establishes easily but is short-lived and you may have to re-seed. 

A shrub that is often used to prevent erosion is Red Osier Dogwood, Cornus sericea. This spreading shrub will grow in areas that flood, as well as in dryer areas so you can plant it at all levels on your bank.  The red twigs will give winter interest and the plant is important to many kinds of wildlife.

Trying a mix of several or all of these plants might be the best bet for success. And you will be making a more complete habitat for your local wildlife.

Sorghastrum nutans

Sporobolus heterolepis

Elymus canadensis

Cornus sericea ssp. sericea