Bracken

Bracken (Pteridium aquilinum) is a common sight in the British countryside. Although less common in gardens, it can be a tough plant to remove. Issues over bracken toxicity and its use as a soil improver are also of importance to gardeners.

Bracken. Credit: RHS/Advisory.

Quick facts

Common name Bracken, brake fern
Botanical name Pteridium aquilinum
Areas affected Gardens and allotments adjacent to infested land
Main causes Bracken spreads via spores and underground stems
Timing Seen spring to autumn; treat in summer

What is bracken?

Bracken (Pteridium aquilinum) is a native British fern commonly found in woodland and heathland. It is tolerant of a wide range of soils and climates.

Appearance

Bracken is typically fern-like, producing triangular fronds, divided into three, that can reach over 1.5m (5ft) in height. In autumn the fronds turn reddish-brown and die back to ground level, with new fronds unfurling from the base in spring.

Why is bracken a problem?

Bracken has thick, fleshy, brown-black underground stems that can travel long distances, often spreading into gardens from adjacent countryside.

Sections of these fleshy underground stems can be introduced to the garden hidden among the roots of plants acquired from infested gardens, or in home made compost or leaf mould.

In cool, woodland gardens, bracken may germinate from spores carried in on the wind.

Bracken can out-compete desirable garden plants and invade bare soil, becoming a weed that is difficult to eradicate.

Bracken Toxicity

Bracken should not be eaten, either by humans or livestock, since it contains carcinogens linked with oesophageal and stomach cancer. Eating the young fronds, considered a delicacy in Japan and parts of North America, is not recommended.

The encroachment of bracken into grazing land reduces the area of useful farmland year by year since livestock cannot be allowed to eat it.

People who have spent all their lives living amongst bracken and breathing in the spores may be at higher risk of getting some cancers, but the danger to the general population and to casual visitors in bracken-infested areas is negligible.

People gathering bracken for composting or eradication purposes are advised not to do so in late summer when the spores are released, particularly in dry weather.

Control

First, consider whether control can be done using non-chemical means such as digging out or covering with mulch. Where these methods are not feasible, chemical controls may be needed.

Non-chemical controls

Bracken is difficult to control, even for farmers and landowners. It can be checked by traditional methods, such as cutting, crushing and burning, but these are labour-intensive and do not kill the underground stems, from which the bracken can regenerate rapidly.

In small areas, try persistent hand tugging to remove emerging fronds, or crush new growth while still soft and tender. If carried out over several years this can progressively weaken and eradicate an isolated infestation. In larger infested areas, making two cuts per year for at least three years may considerably weaken the bracken but is unlikely to eradicate it.

When pulling out bracken stems, wear heavy gloves, as robust stems can splinter and cause serious hand wounds.

Chemical controls

Choose an appropriate weedkiller by reading the label to ascertain the ingredients. Contact weedkillers and systemic, glyphosate-containing weedkillers have no persistence in the soil. Residual weedkillers persist in the soil for several weeks or months and can move deeper or sideways, leading to possible damage of underlying plant roots.

Systemic weedkillers containing glyphosate

For gardeners, glyphosate is the most effective weedkiller available for controlling bracken. Try tough formulations such as Scotts Roundup Ultra 3000, Scotts Tumbleweed, Bayer Tough Rootkill, Bayer Garden Super Strength Weedkiller or Doff Maxi Strength Glyphosate Weedkiller. For best results, apply glyphosate in mid- to late summer (July-August) when the fronds are fully open but before the bracken starts to turn brown in autumn. Spraying younger, smaller fronds is much less effective.

Bracken is quite large by mid-summer, so it may be difficult to spray the bracken without also spraying nearby garden plants. Try pegging them out of the way and protecting them with plastic sheeting.

Residual weedkillers

Where the weed is encroaching from neighbouring land, an annual application in early spring of the residual weedkiller Bayer Ground Clear Weedkiller (containing the active ingredients glyphosate, flufenacet and metosulam) to a broad boundary strip will deter encroaching shoots.

Download

Weedkillers for gardeners (Adobe Acrobat pdf document outlining weedkillers available to gardeners; see sections 4 and 5)

Links

Chemicals: using safely and effectively
Chemicals: using a sprayer
Chemicals: using spot and broad-scale weedkillers

Using bracken for composting or as a soil improver

The young green fronds of bracken can be collected for the compost heap where they will rot down slowly, enriching the nutrient content of the compost. Bracken stems are too woody to be added to the compost or leafmould heap, unless they are first shredded or chopped into small sections.

Bracken produces numerous spores, but these seldom seem to germinate and grow in the compost heap. Small sections of the roots can regenerate, and therefore should not be used in the compost.

Dead bracken collected in autumn can be rotted down to make mulch, in the same way as tree leaves are collected and rotted down to make leafmould.

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