Broad-leaved dock (Rumex obtusifolius)

Often considered a "super-weed" and here's why...

Broad-leaved dock (Rumex obtusifolius) is a resilient, deep-rooted perennial weed found throughout New Zealand. It is known for its large, broad leaves and its ability to out-compete surrounding plants by shading them.

In the garden, Broad-leaved dock is often considered a "super-weed" because it is specifically designed to survive almost everything a gardener throws at it.
If you snap the taproot while pulling it, any segment left in the ground can grow a brand-new plant. The root can grow over a metre deep, tapping into water reserves your flowers can't reach, making it almost impossible to kill via drought. It also acts like a massive battery, storing enough energy to survive repeated mowing or surface-level weeding.

Using a cut-and-paste weed gel is one of the most effective and targeted ways to kill Broad-leaved dock, especially in busy garden beds where you don't want to risk spraying nearby plants.

Because dock has a massive taproot, it needs a systemic herbicide (one that travels through the whole plant) to kill it permanently. Gels are highly concentrated and sit on the leaf or stem, forcing the plant to "drink" the poison right down to the root tips.

1. The Leaves

- Size: They can grow up to 40cm long.
- Shape: Broad and oblong (like a paddle) with a distinct heart-shaped base.
- Edges: Slightly wavy or “crinkled,” but much wider and flatter than its cousin, the Curly Dock.
- Colour: Generally mid-to-dark green, often developing reddish veins or spots as they age or under stress.

2. The Stem & Flowers

- Height: When it flowers, it sends up a thick, ribbed central stalk that can reach 1.5 metres high.
- Flower Clusters: Small, green, inconspicuous flowers grow in dense, tiered “whorls” around the stem.
- Turning Brown: In late summer, the entire flower spike turns a very distinct rust-red or deep chocolate brown as the seeds ripen.

3. The Root

Appearance: A thick, vertical yellowish-brown taproot that looks like a giant, woody carrot.
Texture: Extremely tough and difficult to snap cleanly.

The “Cut and Dab”. It’s as easy as 123.

Cut: Use a spade or loppers to cut the dock through the “crown” (where the leaves meet the root), just below or at ground level.
Paste: Immediately (within 15 seconds) apply a 3-5mm layer of the gel to the entire surface of the cut root stump.
Just Wait: The plant’s “plumbing” starts sealing up as soon as it’s cut. Applying it instantly ensures the glyphosate is sucked down into the root system.
Broad-leaved dock (Rumex obtusifolius).