How to Kill Docks

Docks are one of those common UK weeds that make you feel like you’re losing a war of attrition. You dig one out, feeling satisfied with the thick root you’ve extracted, and three weeks later it’s back – often bigger than before.

That’s because dock taproots can extend up to 90cm (3 feet) into the ground. Unless you’ve removed the top 12-15cm of that root, the plant will regenerate. And even if you do get the root, there are seeds in your soil that can remain viable for 50 years or more.

Understanding what you’re up against is the first step to actually winning.

How to Identify Docks

Two species dominate UK gardens: broad-leaved dock (Rumex obtusifolius) and curled dock (Rumex crispus). Both are common garden weeds that share the same frustrating characteristics.

Broad-leaved dock has large, oval leaves with rounded tips and a distinctive central midrib. The leaves can grow impressively large – up to 25cm long on established plants.

Curled dock has narrower leaves with wavy, crisped edges. It’s slightly smaller overall but just as persistent.

Both species form rosettes of leaves at ground level in their first year, then send up tall flowering stems in their second year and beyond. These flowering stems can reach 1-1.5 metres tall and produce the distinctive reddish-brown seed heads you’ll recognise from roadsides and field edges.

Docks are classified as “injurious weeds” under UK law, alongside thistles and ragwort – landowners can be required to prevent their spread to agricultural land.

Why Docks Are So Hard to Kill

Docks have evolved to survive. Their deep taproots store enough energy to regrow the entire plant from just a fragment. Cut a dock at ground level and it barely notices – there’s a metre of root underground ready to push up new growth.

Then there’s the seed problem. A single dock plant can produce up to 60,000 seeds in a season. These seeds are dispersed by wind, water, animals, and contaminated manure or soil. Once in the ground, they can lie dormant for decades, germinating whenever conditions are right.

This is why docks often appear in ground that’s been recently disturbed. Digging, rotavating, or even just heavy rain can bring buried seeds to the surface where light triggers germination.

How to Kill Docks

Digging Out (The Thorough Approach)

Manual removal works, but only if you’re thorough. The good news is you don’t need to get the entire 3-foot taproot – research shows that removing the top 12-15cm (5-6 inches) of root is usually enough to prevent regrowth. Deeper sections lack the energy reserves to regenerate.

Use a fork rather than a spade. Forks are less likely to slice through the root and leave fragments behind. Loosen the soil around the plant, then lever the root out in one piece.

The best time to dig docks is late winter or early spring, before they’ve had a chance to build up energy reserves or set seed. Tackling them when they’re young – before the taproot has fully developed – is much easier than battling established plants.

Never put dock roots in your compost bin. They’ll survive and spread when you use the compost. Bag them separately and bin them, or drown them in a bucket of water for several weeks until they’ve rotted completely.

Weedkiller (The Practical Approach)

For established docks or large infestations, a systemic weedkiller is the practical solution. Glyphosate is absorbed through the leaves and transported throughout the plant, including down to the deepest parts of the taproot.

Apply when docks are actively growing and have plenty of leaf area to absorb the chemical – late spring through summer is ideal. Avoid spraying in drought conditions when the plant is stressed, as uptake will be poor.

For docks growing among plants you want to keep, use a gel formulation that you paint directly onto the dock leaves. This avoids any risk of spray drift damaging nearby plants.

Large, established docks may need a second application 4-6 weeks after the first, or you may need the strongest weedkiller available. The plant will yellow and die back over 2-3 weeks as the herbicide works through its system. For areas where you want long-lasting weed prevention, residual herbicides can stop dock seeds germinating for months.

Preventing Docks From Coming Back

Killing existing docks is only half the battle. With seeds viable for 50+ years, prevention is a long game:

Never let docks set seed. If you can’t remove a plant completely, at minimum cut off the flowering stems before they mature. One plant going to seed undoes months of weeding effort.

Mulch heavily. A thick layer of bark mulch or wood chips (8-10cm) blocks light from reaching dock seeds, preventing germination. This is one of the most effective long-term prevention strategies.

Maintain dense planting. Docks struggle to establish where other plants are already competing for light, water, and nutrients. Keep borders well-planted and lawns thick and healthy.

Check incoming materials. Dock seeds often arrive in contaminated manure, topsoil, or the rootballs of new plants. Inspect any materials you bring into your garden, and be particularly wary of manure from farms with dock problems.

Frequently Asked Questions

How deep do dock roots go?

Dock taproots can extend up to 90cm (3 feet) into the soil, though most of the regenerative capacity is in the top 12-15cm. If you’re digging out docks manually, removing the top 15cm of root is usually sufficient to prevent regrowth – you don’t need to chase the entire taproot.

Will cutting docks kill them?

No. Cutting removes the leaves but leaves the taproot intact. The plant will simply regrow from its root reserves, often producing multiple new shoots where there was one before. To kill docks permanently, you need to either remove the top section of root or use a systemic weedkiller that reaches the roots.

Do dock leaves actually help nettle stings?

This is traditional folk wisdom, but the science is unclear. Dock leaves contain compounds that may have mild anti-inflammatory properties, and the physical action of rubbing something cool on a sting provides some relief. Whether docks work better than any other large leaf is debatable – but they do conveniently grow in the same damp habitats as nettles.

When is the best time to dig out docks?

Late winter to early spring, before the plant has built up energy reserves and while the soil is still moist enough to work easily. Young docks (first-year plants without flowering stems) are much easier to remove than established specimens. The worst time is late summer when the taproot is at maximum strength.

How do I stop docks coming back?

Prevent any docks from setting seed (60,000 seeds per plant, viable for 50+ years). Mulch bare soil heavily to block germination. Maintain dense, competitive planting. Be careful with manure and topsoil, which often contain dock seeds. Accept that this is a long-term management task rather than a one-time fix.

The Bottom Line

Docks are stubborn, but they’re not invincible. Remove the top 15cm of root or use a systemic weedkiller that reaches the taproot, and the plant dies. The harder part is managing the seed bank in your soil – that’s a decades-long project of vigilance and prevention.

The frustrating thing about docks is how permanent they feel. Cut them, and they’re back in weeks. Dig them, and you’ve left root behind. This gets to the bottom of the problem – literally.