Building a berm in Loveland - Ask Extension
.I am building a 2' berm in a front yard. Some of the area is over grass, towards the outer edges. #1. Can I put cardboard over the grass and add ...
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Building a berm in Loveland #869689
Asked May 22, 2024, 8:09 PM EDT
.I am building a 2' berm in a front yard. Some of the area is over grass, towards the outer edges. #1. Can I put cardboard over the grass and add the topsoil on top of it? I cant dig up the grass because of a large fir tree roots. #2. What dirt should I use? Base layer could be screened fill dirt and topsoil on top? I am trying to go mostly native plants and want to xeriscape much of it. Thanks Lynn
Larimer County Colorado
Expert Response
Hi Lynn,
A couple of questions - are there additional fir tree roots in the area where the berm is going to be located? Because changing the soil grade where there are existing trees can adversely affect the tree's health. Second, do you plan to supplementally water the fir? These are not drought tolerant trees and will need regular water.
While the cardboard on top of the grass, followed by top soil will work, again, putting too much soil on top of the existing grade may result in water moving through the new soil, old soil, and cardboard in ways that doesn't penetrate into the roots of the tree (or future plants).
Because you're planting natives/xeric plants, these are plants that don't need heavily amended soils, so whatever you can find that's closest to our native soils is best. If you do the planter's mix/topsoil mix, you will want to thoroughly mix the two together (to avoid layers).
You might consider consulting with a landscape designer to ensure you take all the proper steps for the best success.
A couple of questions - are there additional fir tree roots in the area where the berm is going to be located? Because changing the soil grade where there are existing trees can adversely affect the tree's health. Second, do you plan to supplementally water the fir? These are not drought tolerant trees and will need regular water.
While the cardboard on top of the grass, followed by top soil will work, again, putting too much soil on top of the existing grade may result in water moving through the new soil, old soil, and cardboard in ways that doesn't penetrate into the roots of the tree (or future plants).
Because you're planting natives/xeric plants, these are plants that don't need heavily amended soils, so whatever you can find that's closest to our native soils is best. If you do the planter's mix/topsoil mix, you will want to thoroughly mix the two together (to avoid layers).
You might consider consulting with a landscape designer to ensure you take all the proper steps for the best success.
Hello Allison, Thank you for your response. The fir tree is huge and I’m only working over 1/3 of the root system, toward the edge of the berm, plus it will get water. Would I be better off using a grass killer? Absolutely hate to do that, and don’t know if that would hurt the tree roots.
Do you know of a landscaper to consult? Or have a list of recommendations?
Hi again,
Using a non-selective herbicide would work, so long as you don't allow the product to come in contact with any exposed roots. Do not use any products that are labeled as "365" or "extended control" as they can be root active and may harm the tree.
The City of Fort Collins has potential landscape designers through the Xeriscape Incentive Program - you can limit your selections on the left side based on your needs: https://www.fcgov.com/utilities/residential/conserve/water-efficiency/xeriscape/incentive-program/resources/professionals/
Using a non-selective herbicide would work, so long as you don't allow the product to come in contact with any exposed roots. Do not use any products that are labeled as "365" or "extended control" as they can be root active and may harm the tree.
The City of Fort Collins has potential landscape designers through the Xeriscape Incentive Program - you can limit your selections on the left side based on your needs: https://www.fcgov.com/utilities/residential/conserve/water-efficiency/xeriscape/incentive-program/resources/professionals/
