What plants don’t like horse manure? Explained

If you have a garden, there’s no doubt that you care about maintaining it and getting the best results from your plants. I can see why you’d want to make sure they’re healthy and provide plenty of fruits or vegetables. When it comes to applying fertilizer to your plants, whether chemical or natural, you may be unsure as to which is best for you. So, what plants don’t like horse manure? Here in this article, I’ve included everything you need to know about the topic.

What plants don’t like horse manure snippet image

Table of Contents

What plants don’t like horse manure?

Tomatoes, cucumbers, peppers, aubergines, root vegetables, and “mid-season” veggies are examples of plants that don’t like horse manure. Horse manures high nitrogen content promotes foliage growth but inhibits fruit development in the aforementioned plants. In terms of root vegetables such as carrots, beets, potatoes, radishes, and onions that don’t require fertilizer by nature, too many nutrients will impede growth rather than promote it.

compost horse manure

Can we use horse manure on flowering plants?

Horse manure is low in potassium and phosphorus, which makes it unsuitable as a fertilizer for blooming plants like roses. If you want to apply horse manure to your blooming plants, do it this way: To improve the soil around the flowering plants, combine horse manure with high potassium or phosphorous sources like dry molasses, bone meal, or fish emulsion.

As a side note, because fresh horse manure contains a lot of ammonia, “mid-season” vegetables including broccoli, lettuce, cabbage, peas, kale, and beans do not flourish when there is too much ammonia. Horse manure is high in ammonia. However, if you want to use horse dung in your garden, be sure to compost it first.

What are the actual disadvantages of using horse manure?

If you’re worried about using horse manure in your garden, it’s crucial that you know what you’re getting into. Knowing the risks lets you be certain that utilizing horse manure is the right option for you:

High nitrogen content

Fresh horse manure has high nitrogen content. While this high nitrogen content may benefit a few plant species, it can be detrimental to others. As I’ve mentioned earlier, raw horse manure is alkaline in nature, so plants and berries that are acidic will not benefit from it.

Undigested materials in manure

Horses usually have a difficult time breaking down their food. In simpler terms, there might be undigested items like seeds and weeds in horse manure. Obviously, these are not helpful for flourishing plant growth.

Longest composting time

While composting horse manure does help a little, compared to other animals, horse manure takes a longer time to compost, which is a great downside. 

nitrogen hungry plants

How to use horse manure as a fertilizer?

You should not use fresh horse manure on plants as it might burn their roots. However, you can use well-aged horse manure or manure that has been allowed to completely dry over winter. You can use well-aged soil without the worry of burning the roots. Of course, horse manure does contain a lot of nutrients required for plants, but it may also contain weed seeds. That is why I recommend using composted horse manure for your garden.

Composting generates heat, which can effectively kill the weed seeds and the harmful bacteria present in the manure. Besides, you can use composted horse manure in your garden all year round. However, make sure you refrain from using horse manure on plants that don’t really thrive well with it.

What is Aminopyralid and how is it associated with horse manure?

Most gardening enthusiasts consider horse manure as a “free” garden amendment. I was one of them until I learned that horse manure happens to be a concentrated source of contamination. Let me elaborate on this…

Aminopyralid is a herbicide that’s used for the control of broadleaf weeds like clovers and thistles on grasslands and pastures. When it binds to plant material, it kills the whole plant.

Horse pastures frequently have broadleaf weeds in them. To get rid of these weeds, artificial weed killers and herbicides containing aminopyralid are generally sprayed. Obviously, aminopyralid residues will be present in the straw used for bedding as well as the hay consumed by the horses.

Therefore, horse manure has a high concentration of aminopyralid’s, which are poisonous to plants. It should be clear now why using horse manure in your garden is not ideal.

horse manure composting


So, what plants don’t like horse manure? To sum up, horse manure is not a good idea for several plants including tomatoes, peppers, aubergines, cucumbers, root vegetables and “mid-seasonvegetables.

  • Make sure you compost the horse manure before adding it to the soil (if you are keen on using it).
  • The high nitrogen content, undigested materials, and aminopyralid contamination make horse manure a “not so good” option, especially for your vegetable garden.
horse manure compost

People Also Ask

Does horse manure take too long to compost?

Yes, it does. Once you pile up the horse manure and leave it aside, it will start decomposing slowly. If conditions are favourable, it usually takes three to four months. If the raw horse manure contains wood chips, it will eventually have a high carbon: nitrogen ratio. In such cases, it can even take a year or more for the horse manure to compost. 

Is horse manure toxic to humans?

Horse manure is natural, biodegradable, and does not contain animal by-products or petroleum. In general, there aren’t any known toxic effects of horse manure exposure on human beings.

Can you put too much horse manure in your garden?

While manure does contain essential nutrients required for plant growth, too much of it can actually be harmful. It is always safe to err on the side of caution. If you are not sure how to go about it, get in touch with a professional gardener or your local extension office.

composted manure

How long does it take for horse manure to break down?

2 years of composting will do wonders for the manure’s texture, and though some nutrients may have dissipated, the quality will be much improved. There is virtually no straw remained after five to six years, resulting in a lovely friable end-product.

How do you rot down horse manure fast?

There are a few things you can do to speed up the process:

  • water the manure regularly so that it doesn’t dry out
  • turn the pile periodically to aerate it and help with decomposition
  • mix in other organic matter like leaves, grass clippings, or food scraps
  • if the weather is too cold, add some warm water or cover the pile with a tarp to trap heat.

Which is better for garden cow or horse manure?

Horse manure is richer in nitrogen and phosphorus, while cow manure has more potassium. Nitrogen helps with leaf growth, phosphorus with root development, and potassium with fruit and flower production. Horse manure also contains more undigested material like straw which can help improve the texture of your soil. So, it really depends on what you are looking for. If you want to add organic matter to improve the texture of your soil, cow manure is a better option. If you are looking to add nutrients for plant growth, horse manure is a better choice.

fresh or composted manure of cows and horses

Do roses like horse manure?

Horse manure can actually be too rich for roses and can burn their roots. It is best to compost the manure before using it on your roses. You can also mix it with other organic matter like leaves or grass clippings to help balance out the nutrients.

Is horse manure good for trees?

Horse manure is a potent fertilizer for fruit trees, but it should not be used fresh. Fresh manure may harm your trees and even prematurely kill young saplings due to the high nitrogen content. It can also boost soil microbial activity, which reduces the number of nutrients available in the soil for trees to absorb.

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Oliver Wright
Oliver Wright

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