Herb robert

Herb robert (Geranium robertianum) has small crane’s-bill pink flowers and pungent foliage. It grows commonly in shaded areas where it can be a useful ground cover but its tendency to selfseed can make it a nuisance as a garden weed.

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Herb robert

Quick facts

Common name Herb robert
Botanical name Geranium robertianum
Area affected Shady borders, rocky areas and paths
Main causes Explosive seed pods spread the fine seed over a wide area
Timing Flowers from spring to autumn; treat from spring to autumn

What is herb robert?

Herb robert is a native member of the hardy geranium family. It is found growing throughout the British Isles and favours shaded habitats such as woods, hedgerows, banks, coastal shingle and rocky places. It is shallow rooted and the pink flowers, although self-pollinated are visited by hoverflies. It can be allowed to grow to brighten shady areas. Learn more about gardening for wildlife and ways to help our bees;

Bees in your garden

Bees in your garden

Wildlife in gardens

Wildlife in gardens

Since herb robert readily self-seeds it is a common annual or biennial weed. This page looks at options for the gardener when herb robert is becoming a problem.


Herb robert has palmately divided foliage which is strongly scented and often reddened, as are the stems.

The pink flowers 8-12mm across are produced throughout the spring, summer and autumn months on plants up to 30cm (1ft) in height.

The problem

Herb robert is a quick growing weed with explosive seed pods which if allowed to flower, will spread rapidly over a wide area.


First, consider whether this can be done using non-chemical means such as digging out or suppressing with mulch. Where these methods are not feasible, chemical controls may need to be used.

The RHS believes that avoiding pests, diseases and weeds by good practice in cultivation methods, cultivar selection, garden hygiene and encouraging or introducing natural enemies, should be the first line of control. If chemical controls are used, they should be used only in a minimal and highly targeted manner.

Cultural control

Herb robert does not root deeply and can be readily controlled by cultural methods such as digging or pulling before flowering or seeding. Hoe off seedlings on a dry day.

Coarse bark mulches will discourage seeds from taking hold.

Weedkiller control

In borders

The non-selective contact herbicides acetic acid (eg. Weedol Gun! Fast Acting or Spot On Fast Acting Weedkiller) and fatty acids (Job Done Garden Ultrafast Weedkiller), or the systemic non-selective herbicide glyphosate can be used in such situations to scorch off foliage. Take care if applying such herbicides between ornamental plants by covering them with plastic sheeting whilst spraying. The covers can be removed once the spray has dried onto the weed foliage.

In uncultivated areas or around established trees and shrubs

SBM Job done Tough Weedkiller (ready-to-use only), SBM Job done Path Weedkiller (ready-to-use only) and Weedol Pathclear products containing glyphosate/diflufenican can be applied once a season to natural surfaces where no plants are to be grown, and can also be applied under and around established woody trees and shrubs. This product kills off existing small green growth and prevents or checks developing growth. Check manufacturer’s recommendations before use to avoid damaging sensitive plants

Inclusion of a weedkiller product does not indicate a recommendation or endorsement by the RHS. It is a list of products currently available to the home gardener.


Weedkillers for gardeners  (Adobe Acrobat pdf document outlining weedkillers available to gardeners; see sections 3a, 4 and 5)


Chemicals: using a sprayer
Chemicals: using safely and effectively
Chemicals: using spot and broad-scale
Weeds: non-chemical control

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