Horseweed: the Native Weed That Took Over My Farm Plot

I did not plant horseweed.

Horseweed did not care.

When we got access to our farm plots in February, the land was mostly bare. It had been cleared, and because this is our first season, most of us were still figuring out where beds would go, laying irrigation, building trellises and generally trying to turn open ground into something that resembled a farm.

Then spring came.

And rain came.

And apparently horseweed took that as a personal invitation.

Anything we had already tilled and planted was mostly fine. Anything we hadn't touched yet? Covered.

Not a cute scattering of wildflowers either. I'm talking dense patches of horseweed across probably half of my quarter-acre plot. Some came up to my waist. Some were taller than me.

At first, I figured I'd knock it down with the weed whacker and keep moving.

Horseweed had other plans.

What Is Horseweed (Marestail)?

Horseweed (Erigeron canadensis, also commonly listed as Conyza canadensis) is a plant native to North America and a member of the aster family—the same family that gives us asters, sunflowers, coneflowers and fleabane.

It can behave as either a winter or summer annual. Some plants germinate in fall, spend winter as a low rosette and shoot upward in spring. Others germinate in spring and move pretty quickly toward becoming the tall, upright plant I met on my plot.

And tall is not an exaggeration.

Virginia Tech notes that horseweed can reach roughly 1½ to 6 feet, which explains why some of mine were looking me directly in my face.

Once mature, it produces clusters of tiny white flowers with yellow centers near the top of the plant.

I never let mine get that far.

Because once I realized what happened after flowering, suddenly pulling weeds for hours didn't seem quite as unreasonable.

One Plant. Two Hundred Thousand Seeds.

A mature horseweed plant can produce up to about 200,000 seeds.

Two. Hundred. Thousand.

And those seeds don't politely fall beneath the mother plant and stay there. They're tiny, lightweight and built to move on the wind.

Which means my fear of letting a half-acre-ish army of horseweed mature and reseed wasn't exactly dramatic.

Virginia agricultural guidance recommends dealing with horseweed before seed production because its wind-dispersed seeds make it extremely good at spreading within and between fields.

So no, I do not regret pulling it before it flowered.

I had enough.

Why Horseweed Thrives in Disturbed Soil

This was probably the most interesting thing I learned about the plant.

Horseweed is extremely good at colonizing disturbed ground.

Freshly cleared areas. Fields. Roadsides. Construction sites. Agricultural land.

Basically: my brand-new farm plot.

Its tiny seeds germinate best close to the soil surface, and disturbed, open ground gives them exactly the opportunity they're looking for.

Which immediately made something on my own plot make sense.

The rows we had already tilled and started farming weren't the problem.

The areas that had been cleared but otherwise left alone were absolutely covered.

The land wasn't randomly attacking us.

We had created exactly the type of open environment horseweed is very good at occupying.

And it did its job very, very well.

About That “Indestructible” Part

I tried weed-whacking it.

That helped aesthetically, I guess.

But chopping the tops didn't remove the roots, and I knew allowing the plants to recover meant giving them another opportunity to eventually flower and seed.

Then we tried mowing.

I watched a riding mower go straight over mature horseweed, rip practically every leaf off the stalk and keep moving.

I looked behind it expecting flattened plants.

Nope.

Bare stalks popped right back up.

Standing.

It felt disrespectful LOL

Horseweed becomes considerably harder to manage as it matures, which is why growers are generally advised to deal with it while plants are young.

Eventually, I discovered the frustratingly simple solution.

Grab it.

Pull.

For something that looked borderline indestructible above ground, most plants came out surprisingly easily by hand.

The problem wasn't pulling a horseweed.

The problem was pulling horseweed over what felt like half of a quarter acre.

My hands hurt for days.

So…If It's Native, Why Am I Pulling It?

This is where horseweed gave me something more useful than another weed-management lesson.

Someone once asked me whether native plants are basically just weeds.

At the time, I knew I disagreed, but I had a hard time explaining exactly why.

Horseweed helped.

Because native and weed aren't opposites.

“Native” tells us something about where a species belongs historically and ecologically.

“Weed” tells us something about our relationship to that plant in a particular place.

A plant can be native to Virginia and still be a weed in my cabbage bed.

Native doesn't automatically mean every plant belongs everywhere.

I keep plenty of volunteers on my plot.

There is fleabane growing out there right now. Ground cherries volunteered. I've left native plants where I've watched pollinators actively use them, and there's one beautiful volunteer shrub I'm still trying to identify.

I'm not interested in turning a farm into sterile rows surrounded by nothing alive.

But I'm also growing food.

Horseweed can grow several feet tall, reproduce aggressively and compete with crops for light, water, space and nutrients.

So, while horseweed belongs in Virginia, several hundred horseweed plants did not belong in the middle of my production space.

Both things can be true.

Would I Grow Horseweed on Purpose?

Probably not.

At least not inside my growing rows.

Horseweed does have ecological value. Its small flowers attract bees, flies and other insects, and the species is native throughout Virginia.

So, if one popped up along a field edge where it wasn't competing with anything important, I might watch it for a while now.

But there's a difference between allowing a native plant to exist and giving a prolific reseeder free rein over your production field.

Inside the vegetables?

Respectfully, no.

What Horseweed Taught Me

I started this season thinking one of my jobs as a farmer was learning what to plant.

I'm realizing another part of the job is learning what the land plants without me.

Horseweed didn't appear because I failed to maintain the plot.

It appeared because bare, disturbed ground opened up and horseweed is incredibly well adapted to fill it.

That doesn't mean I have to keep it.

It does mean I can pay attention.

Native doesn't always mean desirable.

Weed doesn't always mean ecologically worthless.

And caring for land isn't as simple as deciding which plants are “good” and which are “bad.”

Sometimes the question is just:

Is this the right plant, in the right place, for what we're trying to grow here?

For horseweed and half of my quarter acre, the answer was no.

So I pulled.

And pulled.

And pulled.

Now most of the plot is clear, my hands have recovered, and I have one enormous pile of horseweed sitting off to the side that I still need to figure out what to do with.

But that's a problem for another day.

Growing Notes: Horseweed in Virginia

Common name: Horseweed, marestail

Botanical name: Erigeron canadensis / Conyza canadensis

Plant family: Asteraceae

Virginia status: Native and found throughout VirginiaLife cycle: Summer or winter annual

Height: Commonly about 1½–6 feet

Flowers: Clusters of tiny white flowers with yellow centers, generally appearing from summer into fall

Wildlife value: Flowers provide resources for bees, flies and other insect visitors

Propagation: Seed—and lots of it. A single mature plant can produce tens of thousands of seeds and, under ideal conditions, around 200,000

Where it thrives: Sunny, open and disturbed ground including fields, roadsides and agricultural areas

Farm consideration: If you don't want it spreading, remove unwanted plants before they flower and set seed. Younger horseweed is much easier to manage than mature plants