Shepherd’s purse

Shepherd’s purse is a fast growing, prolific annual or biennial weed that can either quickly grow, flower and set seeds in a matter of weeks or, towards the end of the year, overwinter and then flower and seed the following year.

Each plant produces thousands of seeds and huge numbers of seedlings throughout the year, with up to three generations per year. The seedlings quickly colonise large areas of the garden, making it difficult to control if allowed to become established.

These seeds can remain dormant in the ground for several years. And as “One year’s seeding means seven years weeding”, allowing plants to flower and produce seeds, means several years of trying to control and remove it.

Shepherd’s purse is also a host plant for the disease white blister, which affects brassicas, Aubrieta, honesty, wallflowers and several members of the daisy family.

• Beds
• Borders
• Lawns
• Gravel paths
• Between paving slabs
• Waste or uncultivated ground

Shepherd’s purse produces low growing rosettes of variably shaped, toothed green leaves. At just about any time of year, these send up flower stems up to 40cm (16in) high that bare small, white flowers. Overwintering rosettes of foliage start to flower in early spring.

The flowers are very quickly followed by the plant’s distinctive heart-shaped seedpods.

As with most weeds, don’t allow shepherd’s purse to become established. This will make it more difficult to fully control it. Early identification and eradication is very important.

Digging out small plants is a relatively quick – although not necessarily easy – way of getting rid of shepherd’s purse. 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 shepherd’s purse seeds into your garden when buying topsoil or manure. So be vigilant when buying these.

There are a number of weed control options available to treat shepherd’s purse. In addition to traditional weedkillers there are now also a range of more natural alternatives.

Any weedkiller can be used to control and kill shepherd’s purse in beds, borders, waste ground and on paths. Those marketed as “fast acting” are contact weedkillers – killing or damaging the plant tissue they are sprayed onto or make contact with. These tend to be based on “naturally-occurring” active ingredients, such as acetic acid and natural fatty acids.

Systemic weedkillers, that also kill the roots can also be used.

To ensure the weedkiller works effectively:

• Spray the leaves when the plants are growing actively; this is mainly from March/April to September/October. Contact weedkillers will have some effect if used during the colder weather in winter.
• Use a fine spray to thoroughly coat the leaves in small droplets.
• During the summer, spray in the evening to prevent the spray evaporating and to give maximum time for the spray to be absorbed. In spring or if overnight dew is forecast, spray earlier in the day to allow the spray to dry before dew falls.

Most contact weedkillers are total weedkillers – that is they will damage or kill any plants whose leaves they are sprayed on. Make sure you keep the spray off wanted plants – including lawns – and, if necessary protect plants by covering with polythene or similar when spraying.

Use weedkillers safely. Always read the label and product information before use.

Never allow plants to flower and set seed. Although this is pretty easy in your garden, it’s more difficult to stop the seeds blowing in from a neighbour’s garden, any surrounding fields and waste ground and even further afield.

• Spade
• Fork
• Hand fork
• Hand trowel
• Weed-control membrane
• Weedkillers
• Lawn weedkillers