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.
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.
The non-selective contact herbicides acetic acid (Weedol Gun! Fast Acting, Ecofective Spot On Fast Acting Weedkiller, Vitax Garden Weedkiller) and fatty acids (SBM Solabiol Super Fast 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 and 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 3, 4 and 5)
Chemicals: using a sprayer
Chemicals: using safely and effectively
Chemicals: using spot and broad-scale
Weeds: non-chemical control