What’s in your Soil?

Thinking about the basics in the success of any landscape project, I am reminding of a phrase from one of my father’s favorite literary characters.  As Sherlock Holmes would say, “Its elementary my dear Watson”, and so are the elements needed for plants to thrive at your home.  The major player is the soil that surrounds the house and unfortunately is one aspect that most people have no control over.  There are several keys to know about soil in the Midwest that can be changed and some areas where a change in plant may be the only solution.

soil-compost.co.uk

The Midwest is plagued with clay soil, but once compacted a million times by bulldozers and striped of topsoil, your yard is a desolate wasteland.  Above is a picture of good topsoil.  A yard should have at least 6” of topsoil for the best growth for lawn, perennials, and other more shallow rooted plants.   More than six inches would be better.  If the soil has been compacted use a rototiller to break up as much of the soil as you can.  To aerate the soil, sand can be added and for groundcover an addition of compost to help it grow together faster.  Below is a shot of clay soil.  It is typically very difficult to work and may require an ax and not a shovel.

ci.frisco.tx.us

For trees the issues are more complicated.  The ball of the tree is going to be in the clay soil unless you amend the soil more aggressively than is practical.  The most important thing to remember is to dig the hole for the tree bigger than the rootball.  The soil that is put back around the ball, must be the same as the soil dug out of it.  This is why amending the soil around the tree will not be helpful, but harmful.  After the tree roots grow through the amended soil, the tree will have difficulty breaking through to the clay.  If sides of the hole are particularly smooth from digging, such as if a tree spade has been used, rough up the sides to help the roots make it through.

I have found that in some cases a poor site can only be remedied by planting trees that can handle the soil.  Some of the most successful larger trees are Autumn Blaze Maple, River Birch, and smaller ornamentals are Crabapples and Japanese Tree Lilacs among others.  Evergreen trees are especially susceptible to having difficulty in poor soil mostly because clay soils trap water that will kill the roots.  If an evergreen or other less tolerant tree must be used the ball of the tree can be planted a little higher than normal and drainage tiles can be used as a French drain system to alleviate water pooling near the ball of the new tree.

Becca LaBarre

Here is an example from my own work that was a very difficult case.  Almost all the evergreens on this property struggled to establish.  I had Jim Fizzell check this out and the verdicts was that these trees were sitting in water due to clay soil, even the ones that were on a berm.  I was pretty frustrated.  We ended up replacing the trees and planted them higher than normal.  For the worst offenders we planted a few water loving trees instead like River Birch.  I am happy to say that once established the trees took off and are now providing the screening we intended them to provide.

Dealing with poor soil can be a losing and frustrating battle.  I was once told by one our landscape consultants brought in from time to time to help solve difficult cases of dying plants, that it should be expected that a new home site could lose 20% of the plantings due to the poor soil.  It is for this reason that I do find myself sticking to tried and true plants time and time again, especially in areas of newer construction.  Even though soil is an elementary piece to the landscape puzzle, trying to plant in certain soils without care can be like trying to make two plus two equal five.  It just won’t add up.  You may not always win the uphill climb that soil 101 can cause, but follow a few soil rules and you may just beat the odds.

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