The dirty secret about poor soils

Sometimes I have fun at the post office. I go with one of those padded envelopes, and when they ask me whether I need insurance, I say no, it’s just a packet of dirt.

I find this quite funny. I don’t know if the post office workers do. Maybe I’m the third person that day mailing dirt and they’ve seen it all before.

Of course we’re not supposed to call it dirt. My elementary school teacher scolded me once: it’s not dirt, it’s soil! I’ve had soil under my fingernails ever since.

Indeed, soil is one of the most important things we analyze when looking at a potential new site. Soil is food for plants, and as we know, we are what we eat. That’s why I send samples off to a lab.

The lab results tell me a whole bunch of things – organic matter, calcium, potassium, how acidic the soil is. But the number I care most about is nitrogen.

If nitrogen is low, the lab hands me a failing grade. Add fertilizer, it says, otherwise things won’t grow well.

And this is where I part company from the lab. Because low nitrogen isn’t a problem to fix – it suppresses the aggressive plants and weeds that would otherwise take over. It creates conditions where only the tough, adapted species can thrive.

High nitrogen is chaos. Low nitrogen is control.

Working with disaster soil

I’m putting together a plant list for a very challenging site. Part of that site is what’s left over after building work was finished, resulting in soil that is very gravelly, very sandy, and lacking in nitrogen. It’s your classic impoverished soil, and reading between the lines, my soil was nothing short of a disaster.
Traditional landscapers might replace the soil or amend it with compost.

But I’m not going to do that. Instead, I’m going to choose native plants that like that kind of soil.
The plants I’m specifying are known as stress tolerators. Unlike their competitive siblings, they are adapted to poor soils. The big benefit to us is that plants that need rich soils will not be able to compete. That means we will have fewer weeds and more of the plants we actually want instead of competitive chaos in which we are weeding forever.

Now, this does mean we’re not going to get an instant garden. Stress-tolerators are slow to establish. They spend the first year or two putting down roots before starting to spread. But once they’re established, they’re there for good. Because I plant densely in the first couple of years, the plants will cover the ground permanently, locking out weeds and competitive species.

So, which plants am I going to use on this impoverished, sunny, dry disaster of a site? Grasses are often a good bet. Little Bluestem, for example, loves poor conditions. I will add some Sideoats Grama there too, for contrast. Muhlenberg’s Sedge will also thrive. Pussytoes will make a great ground cover as will Prairie Smoke, which will also reward with delicate purple flowers in spring and wispy seed heads later in the season.

For summer flowers, a lot of prairie species will be perfect. Plants such as Hairy Beardtongue, Upland White Goldenrod, and Liatris species will do well here.

I prefer to work with what I’ve got rather than “fix” what’s there. And working with what I’ve got makes life easier for me and my clients because instead of a constant battle with weeds fed on steak, I get a stable landscape that just works.

If you look out there in nature, every inch of ground is covered, even the poor ones. It’s just a matter of choosing the right plants.

Dirt isn’t such a bad thing after all, is it?