What is broadleaf dock?

Accurate broadleaf dock identification matters because this weed looks a lot like its cousin curly dock, and both behave differently from the smaller broadleaf weeds you deal with in a lawn. Broadleaf dock is a European perennial in the buckwheat family that has spread through farm country across the eastern U.S.

It forms a big, low rosette of leaves, then sends up tall flower stalks. The real engine is underground: a thick, yellow, branched taproot with a crown of buds on top. Cut the leaves and the crown simply sends up more.

Each plant can drop a lot of seed, and dock seed is known for lasting many years in the soil, so old pastures and farm fields often carry a big seed bank.

Broadleaf dock identification: key features

Look for these traits:

• Leaves: large, oblong and broad, often close to a foot long, with a rounded or heart-shaped base. The surface is fairly flat and smooth, not crinkled.
• Color: lower leaf stalks and the main veins are often reddish.
• Flower stalks: 3 to 4 feet tall, branched, with crowded tiny green flowers that age to rusty brown.
• Seeds: each seed sits inside three papery wings. On broadleaf dock those wings have small spiny teeth along the edges, which is a reliable way to separate it from curly dock.
• Root: a fleshy, yellowish taproot, usually branched, that breaks rather than slides out when you pull.

In a regularly mowed lawn you may never see the flower stalks. You’ll just see a flat clump of oversized leaves that the mower rolls right over.

Where broadleaf dock grows in Pennsylvania

Broadleaf dock likes rich, moist soil. Around central PA it shows up in lawns built on old farm ground, in pastures and hayfields, along roadsides and ditches, and in damp low spots where water collects. Heavy nitrogen fertilizer tends to favor it, which is one reason it’s so common around barns and manure piles.

New homes on former fields often see a flush of dock in the first few years as old seed comes up in the disturbed soil.

Broadleaf dock look-alikes

Curly dock is the closest look-alike. Its leaves are narrower, with tightly wavy, crinkled edges and a tapered base, and the seed wings are smooth-edged rather than toothed. Its taproot is usually a single main root rather than branched. Control is the same for both.

Red sorrel is a much smaller relative with arrowhead-shaped leaves and creeping roots, and it points to acidic soil. First-year common burdock also forms a rosette of big leaves, but they’re woolly and pale underneath with hollow stalks.

How to get rid of broadleaf dock

Hand and mechanical. For a few plants, digging is the right answer. Use a dandelion fork, a narrow spade or a weeding tool and dig when the soil is moist. The goal is to get the crown and the top several inches of root. Small root pieces left deep usually don’t come back, but a crown left behind will. Young plants are far easier than old ones, so get them early.

Mowing alone won’t kill dock. It does keep it from going to seed, which matters for the long run. If plants have flowered, cut and bag the stalks before seed ripens.

Cultural. Thick turf is your best defense against new dock seedlings:

• Mow at 3 to 3.5 inches so grass shades the soil.
• Overseed thin or bare spots in early fall.
• Don’t overdo nitrogen; dock thrives on rich ground.
• Fix low spots that stay wet, since soggy soil weakens grass and favors dock.

Chemical. For larger infestations in lawns, extension services generally recommend broadleaf herbicides containing dicamba, often combined with 2,4-D and MCPP, or products with triclopyr. Early fall is the best timing for perennial broadleaf weeds because the plant is pulling sugars down to the root. Mid-spring, before flower stalks form, is the second choice. Expect a repeat treatment for old plants with big roots. Read and follow the label (the label is the law), and make sure the product is labeled for your site, whether that’s lawn, bed or pasture. In Pennsylvania, applying herbicide for hire requires a PA Dept. of Agriculture pesticide applicator certification, so larger jobs belong with a licensed lawn-care or vegetation-management company.

Keeping broadleaf dock from coming back

Dock seed lasts a long time, so think in seasons, not weeks. Keep new plants from setting seed, dig seedlings while they’re small, and keep the lawn thick so there’s no bare soil for seed to start in.

After digging or treating, fill the hole or bare patch with good topsoil and grass seed right away. Bare soil is where the next round of dock shows up.

If dock keeps coming back in the same soggy corner of the yard, the bigger problem is often the water. Correcting the grade so the spot drains will help the lawn more than any spray.

Questions we get about broadleaf dock

Similar weeds

Curly DockRumex crispusRed SorrelRumex acetosellaCommon BurdockArctium minus