Herb robert

Herb robert is a hardy annual or biennial wildflower, native to the UK. It is not fussy about soil type, grows in full sun or shade, and is good for pollinators. But, as herb robert readily self-seeds, you may want to limit its spread in your garden.

Save to My scrapbook
© Shutterstock
© Shutterstock

Quick facts

  • Herb robert’s botanical name is Geranium robertianum  
  • The ‘herb’ part of the common name refers to its historical uses as a medicinal herb 
  • Buff-tailed, common carder and white-tailed bumblebees are just some of the pollinators that visit herb robert  
  • The leaves have a distinctive smell, occasionally described as ‘aromatic’ 
  • If you need to control herb robert, non-chemical methods are easy and effective

What does herb robert look like?

Herb robert can reach a height and spread of 40cm (16in), although it will be much smaller in dry conditions. The finely divided leaves have a lacy, fern-like appearance. Leaves and stems are green but they can turn red in autumn or when growing in dry, exposed conditions. Herb robert flowers throughout spring, summer and autumn; some plants have white flowers but usually they are pinkish-purple, ranging from strong shades to pale tints. Fine hairs cover the flower

buds and stems.

Did you know?

In the past, herb robert was used to treat stomach ailments, sores, bruises and wounds, and used as a mosquito repellent.

Is herb robert a weed?

Herb robert has many benefits to gardens and gardeners. It provides nectar for pollinators and is included on the RHS Wildflowers Plants for Pollinators list.

A male orange-tip butterfly feeding from a herb robert flower
Despite its delicate looking, lacy leaves, herb robert is a tough plant, happy to grow in damp soil in a shady corner or a dry crack in a sunny wall. Its useful and attractive qualities are highlighted by nurseries selling Geranium robertianum and its white-flowered cultivars.   

However, because herb robert can multiply easily by seed and is not fussy about where it grows, its spread might need to be controlled. You may want to remove it from areas where it will compete with seedlings and small plants for moisture, nutrients, space and light, but in tricky growing conditions that would otherwise be bare, it can be left and enjoyed.
What is a weed?

The term ‘weed’ describes a plant that is growing where it isn’t wanted. Weeds usually thrive in average garden conditions, reproducing and spreading easily. It is up to you to decide what you call a weed and what you choose to retain or remove.

Frequently asked questions about controlling herb robert

Here are our answers to your most common questions about dealing with herb robert:  

How invasive is herb robert?  

Herb robert has a long flowering season, with individual plants capable of producing many seeds. Ripe seeds are catapulted away from the parent plant, allowing it to spread into new areas. Although numbers may multiply quickly, herb robert, with its shallow, fine root system, is easy to hoe off or pull out.  

Do I need to get rid of herb robert?  

No – with its profusion of pollinator friendly flowers and lacy leaves that colour to red, many gardeners welcome herb robert as a pretty wildflower. It is also useful to have in parts of the garden where many other plants would struggle to grow, although you might decide to remove it from areas where you want to sow seeds or grow small plants. 

What is the easiest way to kill herb robert?   

  • Hoe off plants – hoe veg patches, beds and borders to remove herb robert before it sets seed. Hoe on a warm, dry or windy day, so exposed roots dry out quickly rather than re-rooting. Hoeing removes weeds with minimal soil disturbance.     
  • Pull or fork out plants – this may be a good option if herb robert is growing among seedlings and hoeing isn’t a feasible option. Hand pulling is usually easy, but on compacted soil you may need to use a hand fork.   
  • Smother plants – prevent seeds from germinating and growing by covering the soil in late winter with a mulch of organic matter about 8cm (3in) deep, or a mat of ground cover plants.

Should I use weedkiller? 

As herb robert is easy to control by hoeing and pulling out, there is no need to use a weedkiller. 

For more information, see our page on Weeds: non-chemical controls.  

Join the RHS

Become an RHS Member today and save 25% on your first year

Join now

Gardeners' calendar

Find out what to do this month with our gardeners' calendar

Advice from the RHS

Get involved

The Royal Horticultural Society is the UK’s leading gardening charity. We aim to enrich everyone’s life through plants, and make the UK a greener and more beautiful place.