Berm - Knowledgebase Question

Hoffman Estates, Il
Avatar for gloriadailey
Question by gloriadailey
August 10, 2010
I had a a patio installed and they set it 3 feet above the lawn level, I live in an adult community and have a signle family home but we are all connected with lawns ets., can I plant a berm around the patio with plantings without investing in expensive bricks for a retention wall and planting box area? How do I go about planting a berm? I have 4 plants to use that are japanese silver grass and I want to incorporate other tall grasses in between these plants. Can I do this without investing in a brick surround around the patio? Or is it better to invest in the brick. I am afraid the silver grass will freeze if not deep enough in the ground and if I plant it deeper in the ground they will be to low for the patio. I am in such a delima, can you help me? Any suggestions? I would appreciate any help you can give me.

Answer from NGA
August 10, 2010
Your situation is really challenging! I'm not sure you can build a planting area such as a berm without using interlocking landscape bricks to keep the soil from eroding and washing down under your new patio. It might be possible to build an island type of raised bed where the top is high but the sides slope down to ground level on all sides. If properly formed it would give you high areas in front of the patio in which to plant and then slope down to ground level on all sides. To keep the soil in place you could cover it entirely with weed barrier landscape cloth and cut holes in the weed barrier to plant your ornamental grasses. After planting you'll want to cover over the weed barrier with decorative rocks or bark nuggets or shredded bark. Of course you'll need to import lots and lots of topsoil for your project - more than if you had a raised planter built. You might be able to build a raised planter out of landscape timbers - one that would be solid along the patio side and stepped down on the opposite side so you'd have two or three planting levels. I think this would be the least expensive of all to construct. You can surf the web or check out some landscape design books at your local library to get some ideas.

To address your concerns about the ornamental grasses surviving the winter in a raised bed, you're right - whenever the roots of plants are in a raised bed they are subject to freezing. There are some winter hardy ornamental grasses but even those would need some special care during the winter months. You may be able to prune them down after your first hard frost and then cover over them with several inches of mulch (straw or pine needles/pine boughs are great insulating materials).

I don't think there are any easy answers but I know that you are being very thoughful about the design and potential problems so I'll encourage you to ask lots of people lots of questions. You can get some help from your local Master Gardeners and your local cooperative extension office. Contact: Cook County Unit, Headquarters Office, 4801 Southwick Drive, Suite 100, Matteson, IL 60443, Phone: 708-481-0111. Or you can email the Master Gardener program: [email protected]

Best wishes with your project.

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