Skip to main content

What are problem plants?

While most plants have some value to wildlife, species such as Common Nettle Urtica dioica, thistles Cirsium sp and docks Rumex sp can spread rapidly in meadows or lawns with sub-optimal management and crowd out wildflowers. Small amounts of these species are natural in any grassland, especially along boundaries or corners, large amounts of them can indicate a problem.

However, large swathes of thistles or nettles will result in less space for a diversity of other flowering plants, which could result in a meadow being less valuable for wildlife. Also be aware that an area that has alot of these problem plants already, is usually best avoided altogether if attempting to make a new meadow area.

Preventing problem plants establishing in large numbers is better than a cure . It is best to:

  • Maintain well-managed meadows/grassland vegetation with few gaps
  • Avoid heavy use of the ground during wet weather that could leave areas bare, and avoid scalping by using a low mowing blade on sodden grass
  • Not add nutrients through fertilisers or manure as these problem plants thrive in nutrient-high conditions

 

Problem plant species

Broad-leaved Dock

Dock


Broad-leaved Dock Rumex obtusifolius can grow up to 120cm tall and has wide lower leaves that are slightly wavy-edged. The upper leaves on the flowering stem are narrower. The leaves may be slightly red tinged.

Curled Dock Rumex crispus is like Broad-leaved Dock but has narrower leaves tapered into the stem with strongly crisped edges. Docks are an important plant for a range of insects such as capsids, weevils, beetles, spiders and many other insects.

Thistle


Spear Thistle Cirsium vulgare is a biennial plant, forming a rosette of spiny and sharply toothed leaves in the first year and producing large purple flowering heads in the second year.

Creeping Thistle Cirsium arvense is perennial with wavy-toothed leaves that have slender spines and smaller purple flower heads.

 

Common-ragwort

Common Ragwort


Common Ragwort Jacobaea vulgaris is a biennial member of the Daisy family. Its seed germinates in the autumn producing a rosette of leaves. During the second year, the plant sends up flowering shoots which have multiple yellow flowers.

Common Ragwort is known to support more than 129 other species of invertebrates and has enormous value for wildlife. It acts as a nectar source for pollinators as well as some larvae of flies and beetles which feed on the inside of the flower head. The caterpillars of the cinnabar moth eat Common Ragwort acting as a natural biological control agent. In addition, 14 species of fungi use ragwort as their host.

Common nettle

Common Nettle


Common Nettle Urtica dioica is a coarsely hairy plant with stinging hairs that have a histamine-containing juice. Plants are dioecious – male or female. It has far-creeping underground rhizomes which can spread creating large clumps of common nettle.

It is an important plant for a range of insects such as ladybirds, damselflies, capsids, weevils, beetles, and spiders. Young nettles are the food plant of many moth larvae such as the snout, dot, burnished brass and younger mother-of-pearl and butterflies such as the peacock, small tortoiseshell and comma.

Why are these plants a problem?

Many of them have seeds that are very fertile and spread on the wind, usually dropping far away from the parent plant. A single Common Ragwort plant can produce up to 200,000 seeds, and these can lie dormant in the soil for as long as 20 years. Common Ragwort is also a problem in particular for livestock as the plant contains toxic alkaloids which act as a cumulative poison eventually destroying an animal’s liver.

Some species also have rhizomatous roots that are spreading meaning that they form dense clumps in grassland. Accidently breaking up the roots when removing certain species creates larger clumps as even small bits of root can grow into plants and can remain dormant in the soil for years. For example, Creeping Thistle can create a 20- metre patch in just two years from a small bit of root left in the ground.

 

Spear Thistle, Creeping Thistle, Broad-leaved Dock, Curled Dock and Common Ragwort are classified under the Weeds Act 1959, under which orders can be made requiring their control to help prevent their spread. So, controlling populations of these two species should be undertaken to manage the extent of clumps as total elimination is unlikely to be achievable or desirable.

ragwort

How to manage problem plants

All methods of managing problem plants need patience above all else. Most often it can take years before problem plants are brought back under control.

Essentially pulling by hand is going to be the simplest and least invasive way of managing most of them, or simply cutting the heads off the plants before they flower or set seed for others. However, if you have large numbers of plants and are unable to physically remove them, then spot-spraying can be used. We would always recommend consulting an expert for suitable and available herbicides that will affect the specified problem plants and how to apply the chemicals safely. Spraying is usually most effective early in the season (May or June) before the plants’ flowers are developed. When found along the edge of watercourses, there are additional concerns about using herbicides.

It is important to take care when digging to remove some species, as Creeping Thistle for example can spread further if fragments of roots are left in the soil, whereas digging and removing Spear Thistle is not a problem.

In a well-managed sward, Common Ragwort seldom gets the chance to establish. Pulling and digging is often the most effective control method. Hand tools can be used to make the job easier such as a ‘lazy dog tool’ and a ‘rag-fork’. Gloves must be worn! This method should be done early in the summer before the flower heads mature with best results when the soil is wet. This enables the whole plant to be removed as small bits of root left in the soil can grow becoming new plants. Roots are more likely to break in dry ground potentially creating a larger problem with a halo of new plants around the removed parent plant. Cutting can be used as a method, however it is essential to cut before seed heads are mature and this must be followed with another control technique. Cutting may stimulate the growth of side shoots and vigorous growth in the following year.

Common Nettle is usually best managed through cutting by mechanical means such as a tractor-mounted cutter, strimmer or by hand, using a scythe. This method is best used where infestations of Common Nettle are small, bird nesting is not an issue, equipment and labour are available and where total control is neither desirable nor necessary. Repeated cutting combined with close mowing of the area will weaken Common Nettles and allow the grass to successfully compete over a period of years.

Some other species not considered problem plants

  • Thistles

    There are other species of thistles that are not considered problem plants, such as:

    • Marsh Thistle Cirsium palustre often found in damper grassland
    • Dwarf Thistle Cirsium acaule and Woolly Thistle Cirsium eriophorum often found in calcareous grassland and
    • Melancholy Thistle Cirsium heterophyllum which is present in the north of England, northern Wales and Scotland in grasslands and along roads and footpaths
  • Dock

    There are other Dock species that are present in grassland and are not considered problem plants in the legislation. These include:

    • Common Sorrel Rumex acetosa
    • Sheep’s Sorrel Rumex acetosella (both of which are identified as positive indicators of grassland condition)
  • Ragwort

    There are other Ragwort species that are present in grassland and are not considered problem plants in the legislation. For example:

    • Marsh Ragwort Jacobaea aquatica
    • Hoary Ragwort Jacobaea erucifolia
    • Oxford Ragwort Senecio squalidus

More Meadow Making tips

Yellow Rattle: The Meadow Maker
Yellow Rattle in a hay meadow

Yellow Rattle: The Meadow Maker

Yellow Rattle, is the single most important plant you need when creating a wildflower meadow. Here’s everything you need to know.

How to Start a Community Meadow?

How to Start a Community Meadow?

Want to start a community meadow, but not sure where to begin? Read our guide to creating a flower-filled haven for your local community.

How to Grow a Wildflower Meadow
Wildflower meadow landscape with a variety of species near Cardiff, Wales

How to Grow a Wildflower Meadow

Whether it’s your back garden, local park, community field or lawn, wildflower meadows are amazing spaces with so much to offer.