What Role Soil Plays in Our Plantings

face in soil

If you think about it, there’s a whole world going on below the ground.  It’s like the ocean.

The life that’s going on in these other worlds is meant to work with life above the surface.  How cool is that?

So when the life in the soil is flourishing, so are the plants above.  That has to be good for business.

Know What You Need to Know

I’ve said this before, but I feel like I should say it again.  As “general” landscape contractors, don’t let one topic of our industry consume all your energy.

You want an overall understanding of the fundamentals, and then gradually learn more on what you enjoy and what your business needs to grow.

Soil is a science by itself.  It’s a huge field of study that’s used in several industries – not just agriculture.  I’ve worked on projects where a “soil engineer” was involved.  These guys are generally civil engineers too.  They’re mostly concerned with soil’s impact on construction. (We touched a bit on that in the previous article.)

What are some of the things you should know about soil as a general landscape contractor?

1. Soil texture & structure

Soil is made up of the primary particles: sand, silt, clay and organic matter.  Soil structure is how these different sized particles group together and what the resulting “soil-type” is.

Why is that important? Because these different combinations affect how air and water move through them. This is a major factor for plant health & development. When I mention porosity or how porous a soil is, this is what I’m talking about.

For example, a soil with very little porosity will usually be high in clay.  Its particles are tiny and grouped closely together.  Water will move slowly through soil like this, and there will be very little space for air.  Most plant roots would not penetrate or do well in soil like this.

In fact, when you’re selecting plants you’ll notice that most require a well-drained soil.  They want space in the soil to get air and room for their roots to grow.

2. Organic matter content

As you’d expect, having organic matter in the soil is a good thing, especially for healthy plants. Here’s why:

  • OM helps with soil structure.  For example, adding OM to a heavy, clay soil can make it lighter and more crumbly.
  • OM creates the environment for micro-organisms. Yes that’s good… really good.  We’ll talk more about that later.
  • OM helps bind loose soils together (like sandy soil) and improve water-holding capacity.
  • OM provides plant nutrients in small quantities.
Planting a Weeping Norway Spruce

Adding organic matter during planting phase

3. Soil elements & nutrients

As I mentioned earlier, soil is a science, and things can get pretty complicated.  Elements & nutrients is a soil topic that needs a lot of explaining… and then some. :-)  But here’s the low-down.

There are at least 18 elements that plants need to grow properly.  And although a deficiency of one could affect a plant, the 3 that are typically of concern are: nitrogen (N), phosphorous (P) and potassium (K).  These 3 are primary macronutrients and often needed in larger amounts.

There’s usually enough of the other elements present except in soils that are extremely sandy, acidic or alkaline. (Acidity & alkalinity are measured as pH.  There’s more about pH on p. 19 in your LCF ebook.)

So for soil elements & nutrients I focus on the 3 macronutrients (N-P-K) and the soil’s pH.  In my truck I carry a pH meter like this.  I’m always curious about pH because certain types of plants prefer certain pH levels.  Plus, pH of the soil can affect the availability of nutrients to the plant, like I mentioned.

In general, for planting jobs I’ll assume N-P-K levels are OK unless I notice unusual symptoms on existing plants.  Things like smaller or fewer leaves than normal, and discoloration or veins showing in the leaves can warrant a soil test.  If that’s the case I send out a soil sample to the County Agricultural Extension Service. You can find yours here.  There are also private labs you can use.

You could also do a basic soil test for N-P-K yourself with a kit like this.  But I like the recommendations that come along with the soil analysis from the County Extension Service.

For us in the trade it’s good to know the role of each of the primary nutrients N-P-K.  (I’ll keep this short and simple.)

  • N (nitrogen) is needed for rich, green color in plants. It also causes rapid growth.
  • P (phosphorous) helps new plants get off to a good start – promoting root growth and flowering.
  • K (potassium or potash) is important for overall plant health, including preventing disease.  It’s also key in the fruiting cycle of plants.

I should mention that new restrictions & controls are showing up for fertilizer applications.  For example, environmental laws are being enforced to limit the amount of phosphorous that’s being used.  With water run-off and erosion, phosphorous is moving into our lakes & streams and screwing up the ecology.  If we’re smart and careful we can definitely help control this.

And lastly (because I know this “soil talk” gets old fast). :-)  But it is important …

4. Beneficial microbes & organic nutrients

This, to me, is how we should be thinking about soil.  And fortunately, this is the way the industry is going.

Moving to a more organic approach is good for the environment and especially for the plantings we install and guarantee.  Why not encourage the system that nature has in place?  It works so well.

Essentially for the natural system to work you need beneficial microbes and organic nutrients.  The organic nutrients don’t become available to the plants until the microbes in the soil have digested them.  And once the organics are converted into usable nutrients, they don’t wash away.  It’s this neat, sustainable system.

Basically, a living, healthy soil depends on the microbes.  Here are some other things these little guys can do:

  • Good soil structure occurs because the microbes release a by-product that binds the soil particles and organic matter together.  This makes the soil more porous – and that means oxygen & water gets down deep to the roots.
  • Water retention of the soil increases too.  This will reduce the frequency and amount of watering your customers will have to do.  They’ll love that from an environmental and cost standpoint.
  • Harmful soil pathogens (fungi) are controlled.  The microbes compete for space with the bad fungi and release antibiotic compounds.  Amazing, right?

Soil and our plantings – this is what it comes down to

These 4 aspects of soil that we covered are fundamentals, and you can always expand on them.  But this is a good base to work from.

Make sure you subscribe to trade publications like Green Industry Pro, Lawn & Landscape and Landscape Contractor.  I get them right online.  They’re great for articles on all topics of our trade including soil.  They usually don’t go too deep on things, which is good.  It’s just like we talked about at the beginning – stay informed in a general sense on all topics, and then pursue those you like and support your business model.

Growing your knowledge bit by bit will have you constantly improving as a landscape contractor.  And this information is what you share with your customers & prospects.  It makes them confident they’ll benefit from your recommendations.  There’s no better way to earn trust, sell and grow your customer base.



In the next article we’ll take a look at some ways soil can be part of our business & income – sometimes a big part.

Photo Credit: Face in Soil

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