How to identify common weeds

Use our helpful spotter’s guide to identify some commonly unwanted plants, with links to advice, to help you decide whether to keep them and, if not, how to get rid of them.

Getting started

What is a weed? A weed is a plant growing where it is not wanted. Plants commonly referred to as weeds may have benefits for wildlife, but you may not want them growing in certain areas, or any part, of your garden.

You don’t need to be an expert to identify the weeds in your garden. Our handy guide will help you to spot weeds and check how they grow and spread.

Equipment needed:
  • Wildflower books
  • Plant identification apps – try our identify a plant tool
  • MyAdvice can be used by RHS members for plant identification enquiries

Common weeds

We’ve selected some of the most common weeds. Flowers are particularly useful when identifying a plant, but leaves and growth habit, both above and below ground, will provide clues for identification.

Green alkanet

Other common name: Evergreen bugloss

A hairy-leaved perennial that grows to about 80cm (31in) in height with bright blue flower clusters in late spring and early summer. Regenerates from roots. Spreads by seed.

Herb bennet

Other common name: Wood avens

Perennial with rosettes of leaves made up of three to five rounded lobes. Yellow five-petalled flowers held above to 60cm (24in). Spreads by root fragments and seed.

Couch grass

Other common name: Twitch grass, scutch grass

Blades of grass in clumps. Upright unbranched flower spikes in late summer. Thin wiry white perennial roots form dense mats just below surface level.


Other common name: Bellbind, convolvulus

Twinning perennial climber. White trumpet flowers in summer. Fleshy cream roots run deep and can regrow from small sections.

Japanese knotweed

Tall perennial with bamboo-like stems and tasselled cream flowers. Shoots are reddish-purple when they first appear in spring, with green stems showing purple flecks in summer. Leaves are heart or shovel-shaped and borne alternately (in a zig zag pattern) along the stems. Spreads by invasive roots.

Ground elder

Other common name: Bishop’s weed, gout weed

Leaves appear in spring. Flat heads of lacy, white flowers appear in late spring into summer. Growing to a height of about 45cm (18in). Creates shallow, perennial carpets of thin white roots.


Other common name: Wood sorrel, shamrock

Low-growing, clover-like plants with green or red-purple leaves. Small yellow or pink flowers. Fleshy or creeping persistent perennial roots. Spreads by explosive seed, bulbils and rooting stems.

Lesser celandine

Other common name: Pilewort

A low growing plant with glossy leaves in spring only. Yellow starry flowers to 5cm (2in). Bulbous roots and perennial bulbs break off and spread. Also seeds.

Enchanter’s nightshade

Grows to about 60cm (24in) in height with opposite leaves. Flower spikes of small white flowers and pink buds. Spreads by brittle white perennial roots.


Other common name: Sticky willie, goosegrass

Long sprawling annual to 1m (40in) with whorls of slim leaves. Insignificant white flowers, followed by green bristly seeds, are produced in large quantities.

Herb robert

Other common name: Red robin, storksbill

Pink flowers, red-tinged stems and lacy foliage from a central rosette. Strong musty smell. Annual to 30cm (12in). Spreads by seed.


Other common name: Hairy bittercress, wavy bittercres, ping weed

Annual rosettes of small rounded leaflets. Flower spikes up to about 30cm (12in) of small white flowers. Spreads by explosive seedpods.

Creeping buttercup

Other common name: Creeping crowfoot

Yellow flowers and divided leaves often spotted white. Spreads by seed and colonises by rooting stems making thick, low-growing, perennial mats.


Other common name: Stinging nettle

Two kinds, annual and perennial, both have green flowers and toothed-edged leaves with stinging hairs. Perennial nettles are taller, growing to about 1.2m (4ft) in height. Spread by seed and creeping roots.

Creeping thistle

Other common name: Field thistle

Perennial that spreads out by deep roots and readily seeds. Spiny leaves rise from rosettes. Lilac flowers in summer, with flowering stems ranging from 30cm-1m (1ft-3¼ft) in height.

Rosebay willowherb

Other common name: Fireweed

Ornamental spires reaching heights up to 1.5m (5ft), topped with deep pinkish-purple flowers in summer. Spreads by surface roots and fluffy seed from long pods.

Common chickweed

Other common name: Winterweed, chickenwort

Mat–forming, about 35cm (13in) high, readily rooting annual. Small green leaves, white starry flowers. Produces lots of seed over a long season.


Other common name: Mare’s tail

In spring light brown stems appear, turning into small fir tree-like green plants in summer to about 60cm (24in). Invades by deep, perennial roots, root fragments and sometimes by spores from spring growth.

Annual meadow grass

Other common name: Causeway grass, spear grass

Clumps of narrow-bladed, low-growing annual grass in paths, lawns and borders. Short pale white flower spikes produce lots of seed.


Other common name: Broad-leaved dock, curled dock

Tapered or broad leaves. Flower spikes covered in many small pale flowers in summer, with seedheads, often brown or rusty coloured, persisting into winter. Perennial, deep growing, forked tap roots. Lots of seed produced.

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