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Soil Problems in New Neighbourhoods

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  • March 3, 2017
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Soil is probably the most overlooked part of the landscaping process, and likely results in the majority of plant death, or at least lack of vigour.  In my 1950’s neighbourhood I was lucky to inherit about 24” of good black dirt in both my front and back yard.  There isn’t a Prairie hardy plant I can’t grow in that. 

If you drive a few kilometres out toward suburbia, its a completely different world.  Homeowners are lucky to get 4” of mediocre black dirt, and often less, which barely grows turf.  I lived in a newer area of Sylvan Lake for a few years and the soil was so thin in my front yard I only had to mow my lawn twice per summer.  Is it any wonder the trees on the boulevard haven’t grown in 10 years?

Tree roots need a deep, well-drained, loamy-type soil to grow well.  For shade trees like elm, 18” – or more – of good black dirt is best.  Most roots grow in the top few inches of soil, but if you’ve ever seen a cut-away of the soil on construction projects in mature neighbourhoods, you’ll know that some roots go deep.  And since roots anchor the tree to the earth, having a good quality growing medium will help to ensure a healthy root system, and probably a longer-lived tree.  I like the idea of a stable 50’ shade tree next to my house.

Why Thin Soils?

When a new field is developed for residential properties, the developers remove the top layer of soil, the “black dirt”, and pile it up for re-distribution later.  Roads are built, lots are developed, and the remaining clay soils are heavily compacted by heavy construction equipment.  In the building stage, the ground is further compacted by excavation equipment, and countless vehicles from tradespeople coming and going. 

Prior to the new homeowners taking occupancy, what is to be the new yard is graded by skid-steer equipment, a skiff of black dirt is spread out, and sod is laid down, with a token discount tree in the front yard.  A white vinyl fence is put in and, boom, the landscape is complete.  Next house!  It amazes to see these beautiful million-dollar homes with five hundred dollar landscapes.

But that’s not all.  Often the clay and the black dirt are either worked when wet, or extensively driven on when wet, which turns the clay rock-hard, almost like a concrete.  Roots have a very hard time penetrating those kinds of soil conditions.  So plant growth is slow, leaves look washed out and sickly, and twig die-back is common over the winter.  Combine poor soils with improper planting practices and poor plant selection, and whatever money homeowners have spent on their landscape has been a waste.  To a large degree, this can be prevented with proper soil consideration prior to planting. 

Knowing all this now, if you are planning to have a house built, or are thinking of buying a new one, get involved in the building process with your builder in the early stages, let them know you want 18” of black dirt.  It’s the cheapest part of the construction process and the most overlooked!  Plan on having a lot of the dirt delivered as late in the building process as you can, to avoid compaction.  Source high quality black dirt or garden mix.  If you’re truly ambitious, get a soil sample done and find out what the nutrient profile of the soil is, and add amendments as required. 

If you’re renovating a landscape in a neighbourhood with thin, poor soil, be prepared to remove it and replace with better dirt.

Compaction can be broken up with tillage equipment.  Don’t work the soil when wet.  I’ve never seen any examples of “gitterdun” landscaping that looked good.  Do things when the timing is right.  Make a plan, have it drawn out, and get it looked at by a third party professional, such as an experienced arborist, landscape gardener, or landscape designer.  Take the time to do things right.  Spending a couple hundred on professional advice can save thousands in wasted plant material.

Good soil to a tree is what a warm, comfortable home, with a stocked fridge, supportive family, and good friends does for us.  It provides a good foundation for living, allows us to thrive, put down roots, and live stable lives.  Don’t overlook the importance of soil when designing your new landscape, or renovating an older one.

(c) 2017 Shane LePage, Wild Rose Garden & Tree Service Inc., Red Deer, AB.