Cleavers – sometimes called goosegrass or referred to by its other colloquial names, sticky willy, stickyweed or sticky willow – is a very common annual weed, appearing in both cultivated and bare soil. Thanks to its characteristic ‘sticky’ stems, leaves and seeds, it is easily introduced to gardens from both cultivated and uncultivated soil on boots, clothes and tools, and the fur of animals, and soon becomes a sprawling nuisance in beds and borders. Plants rapidly spread across the soil and set lots of seeds each year, so can quickly smother beds and borders and grow through and over cultivated plants. These seeds can also remain dormant in the ground for up to six or seven years, and germinate quickly when brought to the soil surface by cultivation. So allowing plants to flower and produce seeds, means several years of trying to control and remove it.
Cleavers or goosegrass
(Galium aparine) Cleavers, or goosegrass, is a very common annual weed that appears throughout the garden. It spreads rapidly, sets lots of seeds, and can become a real nuisance.
What are cleavers, goosegrass?
Where do they grow?
- Gravel paths
- Waste or uncultivated ground
Cleavers produces weak, sprawling stems, up to 1m (40in) long with whorls of slender green leaves. The stems, leaves and seed bear stiff hooked hairs, which make the plant “sticky” and easily attach to clothing. Small greenish-white flowers are borne from May to August, developing into round, green or purple fruit.
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.
Digging out the plants when they are more established is more time consuming and more difficult – especially where they’re growing among wanted plants.
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.
Any weedkiller can be used to control and kill cleavers 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 weedkillers work more effectively:
- Spray the leaves when the plants are actively growing; 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 work. In spring or if overnight dew is forecast, spray earlier in the day to allow the spray to dry before dew falls.
Weedkillers (except lawn weedkillers) are total weedkillers – that is they will damage or kill any plants whose leaves they are sprayed onto. 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 should be pretty easy in your garden, it’s more difficult to stop seeds blowing in from a neighbour’s garden, any surrounding fields and waste ground and even further afield.
- Hand fork
- Weeding tools
- Weed-control membrane