How to use horse manure in the garden

Horse manure makes an extremely good soil improver for the garden. Often combined with stable bedding and allowed to rot down for a couple of years, horse manure is perfect for digging in or spreading as a mulch. Fresh manure mustn’t be used directly on the garden as it can actually remove nutrients from the soil and scorch plants, but it can be added to compost heaps.

What is horse manure?

Horse manure is the waste (excrement) that comes from horses. It's often mixed with stable bedding. In stables, the floors are covered with a layer of organic material to absorb the waste that horses produce. Bedding material varies and may be straw, elephant grass (miscanthus), wood shavings, pulp or pellets. If sourcing manure direct from a local supplier, find out the type of bedding material used, as this affects how long the manure should be left to rot down before using.

Why is horse manure good for the garden?

Horse manure is good for gardens because it contains nutrients that help to feed ornamental plants, fruit and vegetable crops. Rotted or composted manure combined with horse bedding is high in organic matter, which acts like a sponge in the soil, holding onto nutrients and water for plants to use, and improving the structure of all types of soil. Horse manure is often regarded as more nutritious than garden compost, however this is a broad generalisation as compost quality varies, depending on the type of waste material and composting method used.

How to use horse manure in the garden

When using horse manure, ensure it's well rotted or composted, and at least six months old. If the horse bedding is wood-based, manure should be at least a year old to ensure the wood in it has broken down completely, otherwise it takes nitrogen (a major nutrient required by plants) from the soil. Bagged manure from manufacturers is guaranteed to be well rotted.

The easiest way to apply horse manure is by spreading it onto the surface of bare soil as a mulch. Autumn is the best time of year to mulch with manure, so worms and other soil organisms have enough time to draw it down into the soil before the next growing season starts.

Early spring is also a suitable time to spread manure on soil, particularly around established plants in borders. Using a fork, spread a 5-8cm thick layer over the soil, breaking down any large lumps as you go. Keep manure away from plant stems as this may cause rot. When spreading manure around low-growing plants or clumps of perennials that have been cut back, you can cover the plants with buckets or trugs to keep them free from manure.

Using fresh horse manure

Fresh manure isn’t suitable to use directly on plants as it will scorch roots, and the bedding material will not have broken down at all. Only add fresh manure to soil that won’t be used for growing for at least six to 12 months, depending on bedding type. However, fresh manure does make a good compost activator, helping to speed up the rotting process and improving the quality of the compost produced.

Potential problems of using horse manure

Manure direct from stables may have several disadvantages. Even well-rotted manure is likely to contain weed seeds, both from hay that the horses have eaten and those that have blown onto manure heaped outside. The same goes for roots of perennial weeds that grow quickly in a manure heap – this means you could be importing problems into your garden.

Weedkiller contamination is another potential danger to be aware of. Ask if the pasture fields have been treated with hormone-type weedkiller used to combat broad-leaved weeds, because the chemical remains on undigested material eaten by horses. It may persist for years and, if contaminated manure is added to your soil, can lead to damaged and distorted plants.

Hygiene precautions

Horse manure may contain bacteria harmful to human health so observe basic hygiene precautions when handling it.

• Wear gloves, sturdy outdoor footwear, and old clothes or a boiler suit
• Wear a face mask if handling dry material
• Do not eat, drink or smoke whilst handling manure
• Wash hands thoroughly after handling manure, even when wearing gloves
• Wash clothes after handling manure

Which plants benefit most from horse manure?

While most plants benefit from an improved soil, there are some types often described as 'hungry' or which need a rich, moisture-retentive soil, so give them priority. These include most fruit plants, roses, dahlias, beans and peas.

Marrows, courgettes, pumpkins and squash are closely related plants that absolutely thrive on a lot of manure. To get a massive crop, plant them directly on top of a manure heap, first making a hole large enough to fill with a bucketful of garden soil to plant into, as the plant may rot if in immediate contact with manure.

Which plants don’t like manure?

Manure is likely to be too rich for drought-tolerant plants and plants that need a free-draining soil, as well as those that require a soil low in nutrients, such as wildflowers.

Root vegetables, particularly carrots and parsnips, shouldn’t be grown on freshly manured soil as the roots are likely to fork. Soil that has been manured at least a year previously is fine and best for all root crops.