Listen to Your Weeds: They’re Telling You About Your Soil

Is a Weed Just a Lost Flower?

“A weed is just a flower growing in the wrong place.” –This quote has become ubiquitous across the digital social landscape. I’m pretty sure I have it saved on my “Just the Words” board on Pinterest, and maybe in my “Landscape Love” board or “Farms & Farming “ boards, too.  But something about this quote has always irked me a little bit, too.  Because, well….are they?

A few days ago I visited my allotment at my community garden. I was there to walk and gaze and “check on” my vegetables and flowers, but as all who garden know, I was there to first look, and then do one thing, and then do another, until I looked up and an hour and a half had passed. What had I been doing? Mostly, I had been weeding. The thing is, these days I feel a bit guilty when I pull weeds, not so much because of that quote which keeps knocking around in my head, but because I know many weeds are entirely and completely edible. They are power-packed with nutrients. Yet up to this point I have not eaten a single weed. Not one. Ever. I dig them out with my much-appreciated Hori-Hori knife and I put them in the compost pile.  I am working on this. And I also feel a pang with every dig because I know that those weeds aren’t just there: they are a signpost—a very strong, neon-flashing signpost—of what’s going on in the soil. They are there either because something is lacking in the soil, or because the soil has too much of something.  In effect, they are signposts of balance:  that the soil is not, in actuality, balanced.  Or, in a few rare instances, that your soil has hit the sweet spot and is balanced.  It can be rich and balanced, or poor and balanced, but some weeds will tell you that regardless of richness or poorness, the soil they are growing in—and the soil the plants you planted which are growing around it are in—is indeed balanced. –There is a reason they call such soil ‘sweet.’

I’m bound and determined to start paying more attention to which weed is growing where, before I zone out and blindly begin my weeding frenzies. Because, barring a soil test, and certainly more naturally, you may not find anything else that so clearly tells you and I about our soil’s balance than the weeds that grow there.

Where Weeds Live

Do you ever wonder why weeds haven’t taken over the earth? I do sometimes, especially when I’m staring at a garden bed being overrun by winding, spiraling bindweed, or pocked with the vertical armies of advancing horsetail. In order for weeds to take over the earth, there would need to be no wild spaces left. No true wilderness. Because weeds live in disturbed earth: roadsides, post-demolition construction lots, yards, sidewalk strips, landfill, concrete, trailsides, paths….gardens. Weeds live because we disturb the soil. We are birds of a feather: you could say we put the “we” in “weeds.” So it’s no wonder, then, that weeds arrive and take up residence in our disrupted and cultivated spaces. To be a gardener is to accept this reality.  But to be a gardener is to also know that the specific weeds which are growing—thriving!—in your garden right this very second are not there by accident.  They are there because of the balance and condition of your soil.

Identifying Weeds Before Removal Is a True Education

It’s hard sometimes to show gratitude to something when we’ve been conditioned to see it as a bane, and more work. Weeds, after all, have a poor reputation. And they do compete for resources with the plants we are cultivating. They can take over, either under the ground, above it,  or sometimes even both (that bindweed again.) I am not going to say to simply leave the weeds in your garden.  But I am going to say that if we take the time to identify which weed we currently have a death-hold on before we remove it, the weed will give us some pretty darn precious information: information that will help guide our soil management, for the betterment of our cultivated plants. In this way weeds are true instructors.

What Weeds Are Telling Us: Some of the Most Common Instructors

Although weeds may not be able to tell us precisely the soil’s percentage levels of NPK: nitrogen, phosphorus, and potassium--as well as other precise mineral & microbe information that a soil test can provide, what they can tell us is about the structure of the soil: compacted, sandy, crusty; overall moisture content: soggy, dry; the PH (potential hydrogen): acidic or alkaline; general fertility; and whether an element is in abundance (perhaps over-abundance) or deficient. Following up with a soil test is wise. But when we’re there, squatting in our boots in the garden in the moment, knowing what weed we’re looking at and why it would be in that particular spot can set us immediately on a path of rectification.  So what are these weeds and what do they tell us? Here are some of the most common:

Dandelion:  Low calcium, compacted soil (Note: Dandelion also thrive in high-potassium soils.)

Bindweed: Compacted, crusty soil

Crabgrass: Low calcium & nutrients

 Dock: Poorly-draining, wet soil

 Purslane: High phosphorous, rich soil

Chickweed: High Nitrogen, rich soil. May be compacted and alkaline.

Goldenrod: Wet soil with poor drainage.

Common Groundsell: Nutrient-rich, fertile soil

 Ragweed: Low fertility soil

 Quackgrass: Compacted soil or heavy clay

 Henbit: High nitrogen

 Pigweed: Highly available nitrogen; rich soil

 Knapweed: Fertile soil; high potassium

 Moss: Low-nutrient, acidic, soggy soil

 Mullein: Low-fertility, acidic soil

 Ox-eye Daisy: Often soggy, poorly-fertile & acidic soil

 Peppergrass: Balanced soil (sweet!)

 Wood Sorrel: High magnesium, Low calcium (often mistaken for clover)

So next time you step outside into our human-disturbed areas and look down, take note of the weeds growing, and what they are telling you about the soil in which they grow. For your garden it can be especially helpful, as different areas of your garden may most certainly not have the same soil.  My allotment, for example, tends to have the same three weeds over and over:  Purslane (high phosphorus, rich soil), Wood Sorrel (High magnesium, low calcium), and Henbit (high nitrogen.) Although soil tests will give me more information, this does give me some to go on, and it certainly opens my eyes to how even a small garden can have quite variable soil, especially, as is the case with my allotment, if it is a fairly new garden which had many different gardeners before me growing in this same 100 square foot plot.

And it makes sense, too: when I look at where the Purslane grows, for example, I see it in the pathway, and I see it in the areas where I have most amended with both comfrey tea and alfalfa meal. Is it possible there’s too much phosphorus? Yes.  That’s what the purslane is telling me, at least. And I think I will take note now, before those weeds go into the compost pile (or before they are harvested to eat!) Knowing how to identify weeds, and what they are indicating in terms of soil health, structure and fertility, is yet another tool we have in our gardener’s toolbelt. So what about “A weed is just a flower in the wrong place?” It appears a weed is in exactly the right place for it to thrive, and by knowing our weeds and what they’re telling us about the soil, we can leave the weed or pull the weed, but not before listening to what the weed is telling us.