Dock plant or dock leaf is a perennial native plant usually referred to simply as ‘dock’. While generally considered a weed in gardens due to its abundant seeding and persistent, vigorous growth, dock is an excellent wildlife plant as the leaves are an important food plant for many insects, including caterpillars, which are eaten by birds and hedgehogs. Applying dock leaves to soothe nettle strings is a traditional remedy.
What are dock leaves?
Dock is a large-leaved and deep-rooted perennial plant. Two species are widespread in the UK: broad-leaved dock (Rumex obtusifolius) and curled dock (Rumex crispus). Both species of dock are listed as ‘injurious’ under the Weeds Act of 1959 which was created with the aim of preventing their spread onto agricultural land, but it’s not an offence to have docks growing in a garden.
There are other, unrelated, native plants that have ‘dock’ in their names, which are not related to broad-leaved or curled dock. These include burdock (Arctium minus) and common bistort (Persicaria bistorta) which is also known as ‘passion dock’.
Where do dock leaves grow?
Dock grows freely in gardens, farmland, and marginal land, particularly on bare soil and newly cultivated ground as the seeds remain viable for many decades. Dock also grows in lawns.
What does a dock leaf look like?
Dock plants form a rosette of large, broad, mid-green leaves which are smooth-edged in the case of broad-leaved dock and wavy-edged in the case of curly or yellow dock. The leaves grow rapidly to around 30cm long. In summer, tall stems of tiny greenish-white flowers grow to 80-100cm high, turning reddish and then dark brown as the seeds ripen.
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Controlling dock leaves
While dock is a beneficial wildlife plant that should be allowed to grow in wilder areas of the garden, elsewhere it can be problematic. Its large leaves can smother other plants and crops, and its deep taproot makes it hard to dig out. What's more, dock self seeds abundantly and its seeds remain viable for up to 60 years, so it can quickly bulk up in number and can be hard to completely irradicate.
Preventing dock is therefore recommended in ornamental and vegetable gardens, and particularly small gardens. However, allowing dock to flourish in areas of large gardens and allotments shouldn't cause problems.
How to control dock without chemicals
Dig out as much of the deep root as possible – a spade with a narrow, deep blade is the best tool for the job. Removing the top 15cm of root is usually sufficient to prevent dock regrowing.
Early spring is a good time to get on top of dock. It's best to remove the plants when they're young and easy to dig up. Where docks have grown through the root systems of established plants, loosen the soil on each side of the plant to carefully pull out the root.
Chemical-free weed control methods such as organic weedkillers and weed burners, will kill top growth and weaken docks but won’t kill the roots.
Clearing dock-infested ground
If you can wait over a year, the easiest way to kill docks and other perennial weeds is to cover the soil with a material that excludes all light. Plants need light to manufacture food, so in the dark, even the toughest weeds will succumb in time. Use a material such as weed control fabric, black polythene or old carpet to completely cover all plants and soil. It’s important to weigh down or bury the edges to keep out all light. After you have successfully killed the dock plants by excluding light, you can clear the area and replant. However, bear in mind that dock seeds can live for up to 60 years so you will need to remove new plants as and when they germinate.
How to dispose of dock roots and seeds
Never put dock roots and seeds in a compost bin as roots survive and, if broken into pieces, then get spread around the garden in future so the one plant becomes several problems. Compost dock roots safely in stout black plastic sacks such as old compost bags, folding over the top to keep out light and leaving for a minimum of a year. Dispose of dock leaves, roots and seeds, in your garden waste collection or take to your council recycling centre.
Controlling dock using chemical weedkillers
As dock is a perennial, the only weedkiller that works is the systemic weedkiller glyphosate (known as Roundup), which kills both the leaves and roots. Other weedkillers kill the top growth, but the plant simply regrows from the roots.
Glyphosate comes in several formulations including gel, ready to use spray or concentrate, which you dilute and apply in your own sprayer. Make sure you always follow all safety instructions – glyphosate is thought to be linked to various human cancers and has been banned for municipal use by many UK councils. If you must use it, apply glyphosate to the foliage only, taking great care to avoid getting this weedkiller on garden plants as it kills everything it touches.
Uses for dock leaves: FAQs
Do dock leaves really help with nettle stings?
While scientific evidence shows mixed results on using crushed dock leaves to rub on nettle stings, this traditional remedy is still widely used, and many people report its effectiveness.
Are dock leaves edible?
Dock leaves are edible although not particularly palatable. If you have kidney disease, bear in mind that dock leaves contain oxalic acid, which, if eaten in large enough quantities, can increase your risk of developing kidney stones. Use the young leaves of curled dock like cabbage, thinly sliced and cooked. The 17th century herbalist Nicholas Culpeper described dock as ‘a wholesome pot herb’.
Are dock leaves poisonous to dogs?
While unlikely to do any significant harm, dock is considered toxic to dogs as its leaves contain oxalic acid, which can cause tremors and an upset tummy and –although extremely rarely – kidney failure.
Are dock leaves good for wildlife?
Dock is a superb wildlife plant as dock leaves are an important food plant for many species of moth, including the colourful garden tiger moth, as well as other insects.