Planting ground cover on steep slope

Asked May 19, 2020, 9:42 PM EDT

Hi! My front yard has a very steep slope that I've determined is not safe to mow and I would like to cover it with ground cover. I would prefer not to do retaining wall terraces. Questions: What is the best technique to plant without risking erosion? I have considered placing coconut or burlap erosion mats and mulch over the grass, creating wells around the plants to catch and slow runoff, using erosion control wattles, using large stones, and various combinations of these approaches. I definitely don't want to rip up the sod except around the plantings. I am willing to weed but am worried that, while the plants are establishing, the grass and the weeds are just going to overtake the mulch or whatever I place down while I have no way to mow or anything. Does that seem accurate?

Hennepin County Minnesota

4 Responses

Hi,
Here is a link to a wonderful publication. The last page deals with best plants for sharp slopes: https://conservancy.umn.edu/bitstream/handle/11299/51549/08464.pdf?sequence=1&isAllowed=y
As far as getting rid of the grass and weeds, you can either use a herbicide to kill everything or you can try this (although I see you have a large site): https://hennepinmastergardeners.org/the-lasagna-method/
Coir matting is organic and is another option.
I think you have a pretty good plan. Looks like a big job!

Thank you!

Just to clarify, the ideas I listed are different things I'm considering but wasn't sure if I should use all of them.

I actually used the lasagna method in my backyard (which is flat) and it worked great. But wouldn't the various newspaper/cardboard sheets risk rolling off the hill? I could use earth staples to keep the sheets down but wouldn't the mulch then just slide off those sheets?

How about adding a coir blanket to this mix? So it would go: cardboard/newspaper pinned by earth staples -> course mulch -> coir blanket -> course mulch? I would also level out berms in front of ground cover/shrub plants and add large stones to break up water flow down the hill. Finally, the very bottom fo the hill slopes down aggressively so I would probably build a ~1-2' tall retaining wall at the sidewalk.

Do you think this would work? And if I cut the lawn one last time super short right before doing the lasagna work, could I count on that to keep the grass and weeds underneath under control long enough for the ground cover to establish and create an adequate carpet to shade them out from then on?

Thanks for your help!

Chris

Also, if I do the lasagna method, will the ground cover be able to spread? Should I leave space around the ground cover plants?

The mulch will slip off the newspaper and cardboard. Using coir to hold it or a straw mat should work. The lasagna method will also keep the ground cover from spreading. I think you will have to add ground cover plants over several years. As the ground cover plants grow you could open up the weed barrier so they can spread. If you have creeping bellflower kill it because it thrives in shade and will be a problem.

Cutting the lawn very short should weaken it a little making the lasagna method work better.
Without knowing what kind of soil you have and familiarity with the site I can’t advise on the retaining wall. If you are trying to hold back the slope they can be hard to build but if it is to make a clean edge it should be successful.