Hairy bittercressHairy bittercress

Name: Hairy bittercress
( hairy cress, popping cress )

Latin name: Cardamine hirsuta L.

Occurrence: A native, annual to biennial plant found in open and cultivated ground, and on rocks and walls throughout the UK. Hairy bittercress is recorded up to 3,800 ft. It is a common weed of gardens, greenhouses, paths, railways and waste ground. It is a particular problem in container-raised plants from nurseries and garden centres.

Hairy bittercress is variable in size and leaf shape. Waved bittercress, C. flexuosa, closely resembles hairy bittercress and is also variable in habit. It is usually annual or biennial but occasionally perennial. A related introduced weed, New Zealand bittercress, C. corymbosa, has become troublesome in polytunnels. It is similar in appearance to hairy bittercress and has the same explosive seedpods but is generally smaller.


Biology: Hairy bittercress is found in flower all through the year but mainly from March to August. It is automatically self-pollinated. Seed is shed in May and June and sometimes into the autumn. There are around 20 seeds per seedpod. The average seed number per plant is 600 but a large plant may yield several thousand seeds. Plants can be found in fruit for 8 months of the year.

There is little germination of the fresh seeds. The seed after-ripens at high temperatures. The higher the temperature the greater the temperature range at which subsequent germination will take place. Germination is increased by a period of dry storage.

Hairy bittercress seed germinates from April to December. There are peak flushes of seedling emergence from July to August and November to December but this varies in different years. Autumn is the main period of seedling emergence. Hairy bittercress can complete its lifecycle in 5-6 weeks. The cycle is longer in rich soils and shorter in poor ones. Seedlings can survive the severest frost.


Hairy bittercressPersistence and Spread: Hairy bittercress forms a relatively persistent soil seedbank.

When the seedpods are ripe the seeds are dispersed explosively for up to 1 m if the plants are shaken by the wind or by weeding operations. The seeds become sticky when wet and can be spread on tools and clothing.


Management: Seedlings should be killed by early cultivations and regular hoeing to prevent hairy bittercress plants flowering and setting seed. Stem fragments are capable of re-rooting following cultivation in moist conditions. Hairy bittercress seedlings should be removed from container plants before the weed can set and shed seeds. The standing areas must also be kept weed-free. Improved drainage may discourage this moisture-loving weed.

Updated October 2007.

Further Information / Links:

For more information on this weed

»UK farmers' case studies

« Back to Annual Broad-leaved Weeds

Comments

  1. Isn't hairy bitter cress edible ? Is there a perennial form ?
    - David Meagher 3---0-2005

  2. I haven't come across anything that actually says it is edible but the name suggests it is and sharp tasting too. I do not know of a perennial form of this particular cress species.
    - Bill Bond 3---0-2005

  3. Do you know when New Zealand Bittercress was first introduced?

    - simon biddulph 4---0-2005

  4. According to 'The Garden' July 1999 New Zealand bittercress was first officially recorded in the UK in 1985 but it had been a problem at the Royal Botanic Garden, Edinburgh since about 1975.
    - Bill Bond 4---0-2005

  5. Yes, leaves are meant to be edible as a salad veg. Not tried it yet..
    - Melanie 1---1-2005

  6. If the seed pods have set and are exploding the seeds when touched, wear eye protection when trying to pull these weeds out.
    - Alan 5---0-2006

  7. According to Richard Mabey's famous book 'Food for Free':
    "Hairy bittercress is a pleasantly tangy plant, fleshier and sweeter than watercress"
    It's nice in salads and sandwiches, so pop some in your sandwich when you're out for a walk.
    - Hannah Fearnley 6---0-2006

  8. Yes it's perfectly edible and very good for you. The idea of pulling these up or using weedkillers on them seems preposterous to me.
    - tricky micky 0---1-2007

  9. why would you treat bittercress as a weed?? it's used as food in many cultures all over the planet! high in vitamins a and d, and high in iron. try eating it next time.
    - herbivore 3---0-2008

  10. Excellent to eat - tastes a bit like watercress, and a good addition to salads. Why buy expensive packeted rocket and watercress when you can eat your weeds? Try ground elder too - great in omelettes.
    - Dick Brown 3---0-2008

Add your comments about Hairy bittercress

Enter the large characters, or the result of the sum, from the image above



All content © Garden Organic  |  Registered Charity No 298104

Garden Organic is the working name of the Henry Doubleday Research Association (HDRA).
We are not responsible for the content of external web sites.