Help us achieve our goals:
make a donation »
Join the RHS today and support our charity
Free personalised gardening advice
RHS members get reduced ticket prices
RHS members get free access to RHS Gardens
Reduced prices on RHS Garden courses and workshops
020 3176 5800
Mon – Fri | 9am – 5pm
Make a donation
I have forgotten my password
Keep me signed in
Register for free to receive our newsletters, add comments to blogs/articles and to save content.
See what events are on near you and browse your bookmarked pages.
Prevent weeds getting the upper hand in your garden with our useful advice
Find out how to control persistent weeds in your garden without having to use chemicals.
Evergreen trees and shrubs are vital components of the winter garden, but green, powdery deposits on their leaves can make them dull and unsightly. These are caused by algae, which are harmless to the plant but they do cut out precious light to the leaf surface.
Lawns in damp or poorly drained conditions can suffer from unsightly problems such as cyanobacteria (an algae-like growth), dog lichen and liverworts. Cyanobacteria in particular can make the lawn very slippery.
Algae, lichens and moss often form green or grey, powdery or mossy, crusty growths on the stems, branches and trunks of trees and shrubs. While this can worry gardeners, these growths are harmless, although may occasionally indicate a lack of vigour in the affected plant.
It is common to find growths such as algae, lichens, liverworts and moss growing on hard surfaces. Contrary to popular belief, they do not damage what they are growing on, but can cause patios, drives, paths and steps to become slippery.
Algae, liverworts and moss will grow on the soil surface of borders, rockeries and containers and are usually associated with compacted soil or poor drainage. Although they don’t harm plants, they can look unsightly, and may inhibit growth of small or young plants.
Green growths such as algae, liverworts and moss can accumulate on the glazing and surfaces of greenhouses, where they are unsightly and cut out light. They can be controlled by improving hygiene and ventilation.
Aquatic weeds (or pond weeds) can normally be tolerated in small numbers, but it is when they make excessive growth that they become a nuisance, particularly in summer. In garden ponds control is relatively easy, but in larger ponds and lakes it is more difficult.
Bamboos are usually desirable garden plants but, if left to grow unchecked, they can become invasive and spread beyond their bounds, turning into a weed. Follow this simple guide to get rid of bamboo, or at least bring it under control.
Hedge bindweed or bellbind (Calystegia sepium) with its pure white trumpet flowers is a familiar sight, choking plants in borders and twining around any plant shoot or cane. The smaller field bindweed (Convolvulus arvensis) with white or pink flowers is problematic in long grass and bare soil.
Bittercress may be small and short-lived but its ability to produce and disperse large amounts of seed makes it an exacerbating weed. Often introduced unwittingly on the compost of container plants, it can be hard to be rid of in a garden.
We're a UK charity established to share the best in gardening. We want to enrich everyone's life through plants, and make the UK a greener and more beautiful place.
Join the RHS today and get 12 months for the price of 9