Understanding and avoiding chemical use

The presence of some pests, diseases and weeds in a garden is often a sign of a healthy, diverse and resilient ecosystem. Even when control measures are required, non-chemical methods are usually effective. Healthy, attractive and productive gardens can thrive without the use of chemicals. Many organisms labelled as pests are a natural part of the garden ecosystem and a food source for other wildlife; many so-called weeds are UK native

A native plant is one that originated or arrived naturally in a particular place without human involvement. In the British Isles, native plants are those that were here during the last ice age or have arrived unaided since. wildflowers that boost the biodiversity

The variety of living organisms (plants, animals, fungi and microorganisms) in a particular environment. Boosting the biodiversity of your garden has many benefits, including supporting wildlife, improving soil health and reducing the likelihood of pest and disease problems. of our gardens.

What is a pest?

The term ‘pest’ has traditionally been used to describe animals, particularly insects, that cause damage to plants. These herbivores are an important part of a garden’s biodiversity and controlling them is often not necessary. Plants are generally able to tolerate some feeding damage, but where populations build up to higher levels, gardeners might decide to take action to reduce numbers. Eradication would be neither practical nor advisable. 

What is a disease?

Plant diseases are caused by micro-organisms, normally referred to as pathogens; these include fungi, oomycetes, bacteria, and viruses. Diseases interfere with the normal functions of a plant, potentially affecting vigour, appearance, flowering, and fruiting. Although in many cases, plants infected with a disease can still be attractive and productive. The likelihood and severity of diseases depends on environmental conditions, the susceptibility of the plant, as well as the presence of the pathogen.

What is a weed?

The term ‘weed’ describes a plant that is growing where it isn’t wanted. Weeds usually thrive in average garden conditions, reproducing and spreading easily. Many so-called weeds are UK native species, and they provide food and shelter for a variety of garden wildlife. While it is up to you to decide what you call a weed and what you choose to retain or remove, remember that most gardens can accommodate some weeds alongside cultivated plants, without them having any detrimental effect.

Simple ways to avoid pest, disease or weed issues:

These methods strengthen plant and soil health, reducing the need for chemicals and supporting biodiversity. 

• Encourage wildlife, as the more diverse your garden ecosystem, the less likely it is that particular species will dominate
• Choose plants carefully, selecting those well suited to the conditions in your garden and, where possible, with resistance to potential problems
• Give plants sufficient space in borders or containers, to minimise competition and improve ventilation
  The introduction of outdoor air into a space, for example, a greenhouse. This airflow can reduce temperature, replenish the gases absorbed by plants and keep down fungal diseases like grey moulds.  
• Look after your plants, practising rotation, mulching, timely pruning and propagation
• Follow good practice in watering and feeding to promote strong pest- and disease-resistant growth
• Inspect plants regularly, as the early removal of weeds, pests and diseased foliage can give good control and prevent the need for further action
• Correctly identify a problem so the most effective non-chemical control method can be used. RHS members can use the RHS Gardening Advice service for help identifying pests, diseases and weeds, and for advice on suitable management
• See our guide to preventing pest and disease problems for more information
• Take a relaxed approach, as a low level of pest or disease damage is perfectly acceptable in most cases

How can pest, disease and weed problems be controlled without chemicals?

Non‑chemical methods are effective for most garden situations and avoid the risks associated with pesticides

Pesticides are substances designed to kill or control the growth and behaviour of living organisms. They are also known as plant protection products and include insecticides, fungicides, herbicides and molluscicides. The RHS doesn’t support the use of pesticides and recommends that gardeners use non-chemical control options whenever needed. .

When gardeners are faced with pest, disease or weed issues, they can choose from an array of non-chemical control methods. These include manual removal of insects, diseased parts or weeds, the use of barriers, traps and deterrents and changes to cultivation techniques.

Beneficial insects and bugs

Managing pests and diseases without chemicals

Non-chemical weed control

Using biological controls (natural predators and parasites) is another non-chemical way to tackle feeding damage to plants. In healthy gardens, this form of pest control happens without any intervention from gardeners – a good example is ladybird larvae and adults feeding on aphid populations that build up on soft plant growth in spring and summer.

Indoors, or outdoors where there is a lack of natural predators, introducing biological controls is an effective option. Biological controls are available to control whitefly, red spider mite,  mealybugs, aphids, vine weevil, slugs, caterpillars and an increasing range of other creatures. See our helpful guides for more information:

Biological control in the home garden

Aphid predators

Wildlife in gardens

This section provides information on the legal requirements of pesticide

A pesticide is a substance designed to kill or control the growth and behaviour of living organisms. It is also known as plant protection product and includes insecticides, fungicides, herbicides and molluscicides. The RHS doesn’t support the use of pesticides and recommends that gardeners use non-chemical control options whenever needed. and chemical use in gardens. The RHS does not support the use of pesticides

Pesticides are substances designed to kill or control the growth and behaviour of living organisms. They are also known as plant protection products and include insecticides, fungicides, herbicides and molluscicides. The RHS doesn’t support the use of pesticides and recommends that gardeners use non-chemical control options whenever needed. and encourages gardeners to explore non-chemical alternatives.

Chemical products used to control pests, diseases and weeds are regulated under UK law. Pesticides are substances designed to kill or control the growth and behaviour of living organisms and therefore their use carries risks to people, wildlife and the environment. Using pesticides is not something gardeners should undertake lightly.

The Food and Environment Protection Act (FEPA) 1985 and associated regulations extend to wood preservatives, animal repellents and materials that control plant growth, such as hormone

Chemical substances that regulate plant growth and development. There are several types of plant hormones, including auxins, cytokinins, gibberellins, abscisic acid and ethylene. These hormones play important roles in processes such as cell division, elongation and differentiation, as well as in responses to environmental stimuli such as light and gravity. rooting powders. Fertilisers, garden disinfectants and cleaning materials are not considered pesticides, although they may be covered by legislation relating to biocides.

It is illegal to sell unapproved products for use as pesticides. The Health and Safety Executive (HSE) database can be used to check if a product is authorised for use in the UK. Some pesticide products sold online may not be authorised for use in the UK. It is not advisable to use household products, such as bleach, vinegar or washing-up liquid, as pesticides. Gardeners mixing up their own solutions from household products often damage plants, soil and soil organisms, and may also harm the wider environment.

Pesticides approved for home gardeners are legally available to buy, but should only be used as a last resort and strictly in accordance with the label instructions. Adhering to the label instructions is a legal requirement. Pesticides should be kept in their original labelled containers. For more information, see our helpful guides:

Chemical labels explained

Storing and disposing of chemicals safely

Withdrawn chemicals

Before resorting to pesticides

Pesticides are substances designed to kill or control the growth and behaviour of living organisms. They are also known as plant protection products and include insecticides, fungicides, herbicides and molluscicides. The RHS doesn’t support the use of pesticides and recommends that gardeners use non-chemical control options whenever needed. , it is important to bear in mind that:

• Garden chemicals are expensive and their production, packaging and transport all come with environmental costs 
• Insecticides are usually non-specific in what they kill, so beneficial organisms are killed as well as pests (this includes organic pesticides and home-made solutions)
• Regular use of pesticides can lead to the development of resistance; there is a growing list of pests, diseases and weeds that are no longer controlled by chemicals that were once effective
• Accidental spillages and the incorrect disposal of pesticides and containers commonly cause environmental damage
• Treatment with chemicals is rarely necessary – non-chemical controls are usually effective and sufficient

After all this, if a gardener still decides to use pesticides, being aware of the precautions and considerations below will help to limit risks to people, wildlife, pets and the environment. The following information is provided to minimise harm where pesticides are used as a last resort; it is not intended to encourage pesticide

A pesticide is a substance designed to kill or control the growth and behaviour of living organisms. It is also known as plant protection product and includes insecticides, fungicides, herbicides and molluscicides. The RHS doesn’t support the use of pesticides and recommends that gardeners use non-chemical control options whenever needed. use.

1. Care should be taken when selecting a product

• The cause of a problem should be identified correctly. Comprehensive RHS web pages on common pests, diseases and weeds are free and available to all. For RHS members, the RHS Gardening Advice service can help with identifying problems. Inaccurate identification could result in unnecessary use of a pesticide.
• The correct time to apply a chemical should be determined. Pests often have one or more stages in their life cycle when they are more vulnerable to chemical control; spraying at the wrong time will give little or no control. Plants should be inspected at regular intervals so that problems are tackled before heavy infestations have developed. 
• Product labels should be checked before buying. Labels include information on when, where and how often the product can be used. Buying large amounts of pesticide that will take many years to use should be avoided to reduce waste and environmental risk. If only a few plants require treatment, a ready-to-use formulation is likely to be more appropriate. 
• There may be specific restrictions relating to edible plants. Some pesticides shouldn’t be used on edible plants. Others may have a required interval between application and harvest (harvest interval) and/or a maximum number of applications permitted per growing season. 

2. The instructions on the label should be strictly adhered to

• Product labels should be read carefully before use. Labels include important information about dilution rates and maximum dosages.
• Pesticides shouldn’t be mixed together. Products should only be mixed if the manufacturer’s instructions state this is permissible. This includes foliar feeds and liquid fertilisers. 

3. Safety measures need to be in place to protect the user and others

• People and pets should be excluded from the area. Children, vulnerable adults and pets should be kept well away from the area during spraying and at least until the foliage is dry. 
• Direct contact with pesticides must be avoided. Care should be taken to prevent pesticides coming into contact with exposed parts of the body, particularly the eyes and mouth. Smoking, eating or drinking while using pesticides is not allowed. Any splashes should be washed off immediately and hands should be washed after use. Wearing rubber gloves when handling and applying pesticides is a sensible precaution. The risk of inhaling dusts or sprays is reduced by remaining upwind during use.

4. Chemicals should be stored safely

• Equipment should always be cleaned after use. Sprayers should be rinsed with three washes of a small amount of water, which should be sprayed onto areas or plants listed on the label.
• Chemicals must be kept somewhere safe. This should be a cool, dark, frost-proof place, preferably in a locked container where children and pets cannot gain access. Chemical products must be kept in their original containers with the tops firmly closed. 

5. Measures must be taken to avoid damaging the wider environment

• Equipment should be checked. When using sprayers or watering cans to apply chemicals, leaks and blockages can be detected by testing them with clean water first.
• Separate equipment should be used for different types of pesticide. When using concentrated products, rather than ready-to-use products, separate sprayers for applying herbicides and insecticides/fungicides should be used to avoid the risk of contamination. 
• Checks should be made to avoid drift and potential plant damage. Pesticides should not be used in wet, windy, very calm or hot, sunny weather. They also shouldn’t be used on plants suffering from drought. A product can initially be applied to a small area of a particular plant to assess the plant’s sensitivity.
• Open blooms must not be sprayed. Spraying pesticides onto flowers (including weeds) puts bees, butterflies and other pollinators at risk.
• Particular care must be taken to avoid contaminating water. Fish and other wildlife in lakes, ponds and watercourses are very susceptible to pesticides. Contamination is caused by flushing surplus pesticide down toilets or drains, applying weedkillers to hard surfaces where runoff might enter drains, and pouring pesticides onto soil to dispose of them.

The RHS encourages all gardeners to boost biodiversity

The variety of living organisms (plants, animals, fungi and microorganisms) in a particular environment. Boosting the biodiversity of your garden has many benefits, including supporting wildlife, improving soil health and reducing the likelihood of pest and disease problems. in their gardens. Rather than using chemicals, we believe that avoiding pests, diseases and weeds by good practice in cultivation methods, cultivar

Gardeners often use the word variety when referring to a specific plant, but the correct botanical term is 'cultivar'. Whichever word you use, it means a distinctive plant or plants, given a specific cultivar name and usually bred to enhance certain characteristics, such as flower or fruit size, colour, flavour or fragrance, plant size, hardiness, disease resistance, etc. Additionally, it is worth knowing that, botanically, variety has another meaning - it refers to a naturally-occurring distinct plant that only has slight differences in its looks. For example, Malva alcea var. fastigiata differs from typical plants by having an upright habit. selection, garden hygiene

Regular cleaning and tidying not only keeps a garden looking neat, but can reduce pests and diseases too. Beneficial jobs include collecting fallen leaves, promptly removing diseased growth and debris, cleaning tools, and weeding. Still, too much tidying can discourage wildlife, so it’s a fine balance. and encouraging or introducing natural enemies, should be the first line of control. If a gardener decides to use chemical controls, they should be the last resort, and should only be used in a minimal and highly targeted manner. For example, where pests, diseases or weeds pose a serious threat to the wider environment, to important heritage specimens, to habitat, or to native

A native plant is one that originated or arrived naturally in a particular place without human involvement. In the British Isles, native plants are those that were here during the last ice age or have arrived unaided since. wildlife. Notifiable species are regulated separately, and government requirements must be followed at all times.

The RHS Sustainability Strategy states that our aim is to be biodiversity net positive by 2025. This applies to our operations and to the gardening information and advice we provide. As part of this initiative, since spring 2023 the RHS has stopped selling registered pesticides

Pesticides are substances designed to kill or control the growth and behaviour of living organisms. They are also known as plant protection products and include insecticides, fungicides, herbicides and molluscicides. The RHS doesn’t support the use of pesticides and recommends that gardeners use non-chemical control options whenever needed. in our Plant Centres and online.

To drive forward our integrated approach, we encourage and manage wildlife in our gardens. By making our gardens a haven for wildlife, they provide a natural balance. We also actively accept some damage to plants as this is a vital part of managing a healthy garden.