Digging out small plants is a relatively quick – although not necessarily easy – way of getting rid of scarlet pimpernel. A fork and hand fork are usually better tools than a spade and trowel. Digging out larger plants when they are more established is more time consuming and more difficult – especially where they’re growing among wanted plants.
Regularly hoeing seedlings and young plants as soon as you see them is the quickest and easiest method of control. The aim of hoeing is to sever the weed stems at or just below ground level, cutting the top growth from its roots. A sharp hoe blade will make this even quicker and easier, so always sharpen the hoe blade before using it. Hoeing on a warm and/or windy day will mean plants quickly dehydrate and die.
Flame guns and weeders that use an electric current are also effective in some locations.
Covering bare soil with weed-control membrane (landscape fabric) or even thick black polythene will exclude light and prevent seeds germinating. As will mulching the soil with organic matter, such as a bark mulch. For mulches to work properly, they need to be a minimum of 5cm (2in) thick, but 7.5cm (3in) deep works better.
In lawns, regular mowing throughout the year and the use of lawn fertilisers and lawn weedkillers should weaken and eventually kill it.
You may unknowingly introduce scarlet pimpernel seeds into your garden when buying topsoil or manure. So be vigilant when buying these.