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 methods are more successful if applied before the weed has had time to set seed. Where infestations of bittercress are light, fork out before the weed sets seed. Among ornamentals or vegetable crops, careful hoeing or hand weeding is the only practical means of destroying either weed. If, however, they have been allowed to seed, they may remain a recurring problem for some time.
On borders or bare soil, a deep mulch (15cm (6in)) of organic matter such as garden compost or bark should help suppress the weed.
On unplanted land and path-sides contact weedkillers such as acetic acid (Weedol Gun Fast Acting), fatty acids (SBM Solabiol Super Fast Weedkiller) and pelargonic acid (Doff 24/7 Fast Acting Weedkiller) can be used to control the annual species Cardamine hirsuta.
With heavier infestations of Cardamine flexuosa apply the herbicide glyphosate (e.g. Roundup Fast Action, SBM Job done General Purpose Weedkiller or Doff Advanced Weedkiller), letting the weed grow to flowering stage before application. When using glyphosate take care to avoid leaves and other green parts of all garden plants as it is not selective in action. Used with care, glyphosate can be used around the base of non-suckering woody plants, as long as the bark is woody, brown and mature. Glyphosate is not active through the soil and there is therefore no risk garden plants will absorb it through their roots.
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 section 3 and 4)
Chemicals: using a sprayer
Chemicals: using safely and effectively
Chemicals: using spot and broad-scale weedkillers
Weeds: non-chemical control