Cracks between paving and less worn areas at the edges of paths and drives are colonised by unwanted vegetative growth. This can make the area unslightly, uneven or slippery when wet.

Other primitive growths such as moss and algae can also build up in these situations. The control of these is dealt with on our specific advice page.

This page looks at options for the gardener when weeds are becoming a problem on hard surfaces.
 

Weeds and unwanted growth on hard surfaces can be unsightly, giving a scruffy unkempt look. They are often restricted in size due to the poor growing conditions and shallow root run but this does not stop them from flowering or setting seed.

Weeds on hard surfaces are usually common weeds of lawns or waste ground such as annual meadow grass and creeping buttercup that have blown in as seed. Occasionally weeds such as mind-your-own-business encroach from adjacent beds.

Border plants that have self-seeded in the wrong place may also require control on paths and drives.

First, consider whether this can be done using non-chemical means such as digging out or other methods like burning or the application of hot water. 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.

Cultural control

Deep-rooted plants such as dandelion and dock require the removal of their tap root. This can be tricky in crevices or cracks. Specially designed narrow-bladed weeding tools – sometimes called ‘dandelion weeders’ – for tackling such weeds are the most effective. More generally, a ‘block paving knife’ can be run along between pavers to sever most weeds. A wire-bristled ‘block paving brush’ is good at removing moss and the smaller weeds.

On loose gravel drives, hoeing on a dry day may be successful on shallow-rooted weeds.

Flame guns or flame weeders can work on hard surfaces, especially in warm dry weather. The localised heat ruptures the plant cells, causing it to die back. Two applications work best; the first applied to cause discoloration of foliage and, a week later, the second to burn the dead leaves. Control is best on annual weeds and young perennials. Gas canisters to power the gun can be bought at hardware stores.

Hot water weed control equipment for hard surface use is available to professionals. In a garden it is possible to use hot water from the kettle or left over from cooking vegetables, to achieve similar results. On lush growth, cut back the tops of the weeds first to expose the crown. Keep the spout very low to avoid splash. Wear heat-proof gloves to protect from steam and closed-toe shoes. As with the flame gun, persistent perennial weeds may regenerate, but should succumb to repeated treatments. 

Weedkiller control

Annual and young perennials weeds can be scorched off with a contact weedkiller such as fatty acids (Job Done Ultrafast Weedkiller) or acetic acid (Weedol Gun! Fast Acting, Spot On Fast Acting Weedkiller, Resolva Fast Weedkiller) or pelargonic acid (Doff 24/7 Fast Acting Weedkiller or Resolva Xpress Weedkiller). Established perennial weeds can be weakened and eventually killed off with contact weedkillers, but several applications are likley to be necessary. 

Weedkiller treatment should be directed as a narrow spray to treat only the weed infested cracks and not the whole paved area. Weeds growing around manhole covers and drains should be treated by non-chemical methods.

The use of bleach or salt to kill weeds on paths and drives is strongly discouraged, as this can cause pollution and damage 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.

The RHS does not support the use of weedkillers and recommends that alternative control methods are used. However, we do note that when gardeners struggle to control plants with cultural methods, regulated weedkillers/pesticides for home gardeners are available for use legally. Garden centres and large retailers selling weedkillers have trained staff who can advise on suitable products for your needs.

Links

Chemicals: using a sprayer
Chemicals: using safely and effectively
Chemicals: using spot and broad-scale weedkillers
Weeds: non-chemical control