Complete guide to garden manure

What is manure?

Manure for garden use is animal poo mixed with their bedding, which is material such as straw or wood shavings. Combined, these have been composted or left to rot down for at least six months, preferably a year if woody shavings have been used for bedding. The phrase 'well-rotted manure' is often used to emphasise this, as fresh manure isn’t suitable to use because it would scorch plant roots and the bedding material wouldn’t have broken down.

'Green manure' is the term used to describe plants that are grown specifically for the purpose of digging in and improving the soil. They have the same role as animal manures – they help improve the structure and nutrient holding capacity of soil, but they do so without the use of animals. Many vegan or ethically conscious gardeners use green manures instead of animal manures.

Different types of manure

Horse manure

Horse manure is a good, easy-to-use manure with a sweet fragrance and no sticky residue, and is widely available from local stables but is rarely available from garden centres and other retailers. Be aware of several potential disadvantages: locally sourced horse manure is likely to contain weed seeds, both from hay that the horses have eaten and from wind-blown seed when the manure was stacked outside. It may also have been contaminated with weedkiller, which lasts for a long time and could cause plant growth deficiencies when used. If possible, ask the stables if the manure may have been contaminated by weedkiller, which can persist and damage plants.

Cow and pig manure

Occasionally cow or pig manure can be sourced from local farmers who keep their stock under cover for part or all the year. Both are useful in the garden, with pig manure being quite 'sticky', which is good for improving sandy soils. When buying these manures, it's worth considering where the animals have been kept, and in what conditions, as 'factory farmed' animals are kept inside throughout their lives and are routinely given medication or antibiotics to prevent disease. While not necessarily detrimental to plants, you may have ethical reasons for shopping around.

Cow manure is often sold as 'farmyard manure' from garden centres and other retailers. It may not consist entirely of cow manure, and could be a mixture of cow and other manures, usually from unknown sources. However this manure will be composted at high temperatures and will be free from weed seeds.

Alternatively, a local farmer may deliver a trailer load of manure for an agreed fee. Some Young Farmers Clubs do occasional 'dung runs' – look out for adverts in your local paper.

Chicken manure

Droppings or manure from chickens or poultry raised at home (or by a friend or neighbour) isn’t ideal to use directly on plants, especially when fresh, as it's very strong and likely to scorch plant roots. However, poultry manure is excellent to mix with garden waste in a compost bin, as it's high in nitrogen so will speed up the decomposition process and improve the final quality of the compost. Add a thin (5cm) layer of fresh poultry manure to every 30cm or so of green waste, and then leave it to compost for at least six months.

Dried chicken or poultry manure in pelleted or granular form is a type of fertiliser, rather than a bulky manure. Again, you might want to shop around if you want to avoid manure from intensively farmed chickens.

Pet manure

Droppings and bedding from plant-eating (herbivorous) pets such as rabbits and guinea pigs is fine to compost and use on the garden. Do not use cat or dog poo, as this may contain harmful parasites, along with pesticides from flea and worming treatments.

Other types of manure

Manure from herbivorous animals such as sheep, llamas and alpacas, is all suitable to use on the garden or to add to the compost heap.

Green manures

Green manure plants are sown directly into the ground, then dug back into the soil when young to break down and improve its structure and nutrient content. These plants are also sometimes called 'cover crops' when sown in summer or autumn to cover bare soil over the winter, protecting the ground from winter rains and preventing nutrients being leached out. While growing, green manures provide a habitat for certain species of wildlife, including ground beetles. Popular green manure plants include mustard, ryegrass, buckwheat, phacelia and winter tares.

• Complete guide to green manures

How to use manure

Either spread manure on the surface of bare soil or dig it into the ground.

Fresh manure (less than six months old) is too strong to put directly onto growing plants, but it can be spread or dug into soil that is being prepared for growing later on. Fresh manure is excellent to add to garden waste in compost heaps or bins, as it speeds up the composting process and improves compost quality.

When's the best time of year to spread manure?

Autumn is the best time to spread manure on the surface of bare soil on vegetable beds or around plants in borders. This gives worms and other soil organisms time to gradually take the manure into the soil before plants start growing again in spring. Another benefit is that by applying manure in autumn, the soil also gets protection from heavy winter rains, which can lead to the leaching of nutrients.

Spring is also a good time to spread manure on soil around established plants. If preparing ground for sowing seed of vegetables or flowers, you'll need to dig it in.

How to spread manure

Spread manure in a 5-8 cm layer on the surface of bare soil. Break up large lumps as you work. Ensure manure doesn’t contact plant stems as this may cause rotting.

If large quantities of bulky manure need to be moved and spread, buying a manure fork and a flat-headed shovel will make the job easier. For small quantities or if using bagged, composted manure, a standard garden digging fork will suffice.

Which plants don’t like manure?

Manures are too rich for drought-tolerant plants that need a free-draining soil, or for those that do best on a poorer soil that is low in nutrients. Root vegetables such as carrots and parsnips shouldn’t be grown on freshly manured soil as the roots are likely to fork as the plant reaches out in several directions for the plentiful nutrients. Soil that has been manured at least a year previously is fine.

Hygiene precautions

Manure may contain bacteria harmful to human health so following basic hygiene precautions is strongly advised.

• Wear gloves, sturdy outdoor footwear and old clothes or a boiler suit
• Wear a face mask if material is dry to avoid inhaling particles
• Do not eat, drink, or smoke whilst handling manure
• Wash your hands thoroughly after handling manure, even if you have been wearing gloves