Is mushroom compost good for potatoes? (lets find out)





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If you love mushroom compost, you may be wondering whether you can use it for growing potatoes. Mushroom compost has lots of advantages, but it’s important to know what your plants need before you put them into mushroom compost.

It’s okay to use mushroom compost with potatoes, but you will need plenty of other soil too, because mushroom compost does not have enough nutrients for growing potatoes. Additionally, mushroom compost has quite a lot of lime in it, which can cause scab on potatoes.

You can definitely use some mushroom compost when growing potatoes and it will benefit the plants if you do so. However, there are some drawbacks, so we’re going to weigh up the pros and cons today.

What Are The Advantages Of Using Mushroom Compost For Potatoes?

If you are going to use mushroom compost for your potatoes, it’s important to know what the benefits of doing so are – and there are quite a few! However, it is important to note that these benefits are usually gained by adding the mushroom compost to other fertilizers and soils, rather than using it neat.

Some of the top reasons for using mushroom compost for potatoes include:

  1. It will fertilize the potatoes and help them to grow
  2. It can be used as a mulch to keep the potato plants damp because it holds moisture in the soil
  3. It will serve as a mulch to trap warmth in the soil
  4. It can improve the soil structure and drainage
  5. It contains some nitrogen
  6. It’s sustainable

Let’s look at each of these benefits in a bit more detail so you really understand why adding mushroom compost to your potato beds might be a great idea.

1) It Is A Fertilizer

Although mushroom compost is not the richest source of nutrients you can find, it does contain some helpful and critical nutrients and minerals that your potato plants will benefit from. It is a slow-release fertilizer, which makes it popular with many growers who want their beds to keep feeding their plants in the long term.

Mushroom compost has usually been used to grow mushrooms in before it is used for fertilizer, so you should be aware that some of the nutrients will have been used – but some will remain. People tend to view it as a “light fertilizer.” It will feed your potatoes, but won’t give them enormous amounts of nutrients.

2) It Will Keep The Plants Damp

Mushroom compost is known for its water retention properties, so it’s a great way to reduce how frequently you need to water your beds. It will keep your potato plants nicely damp while they grow, minimizing the risk of them getting dried out.

3) It Can Be Used As Mulch

Mushroom compost tends to be pretty cheap, as it is a product that has already been “used” so it is almost a waste product. That means you can create a really deep layer of mulch from it without spending a fortune, because you can buy a lot of it for very little.

Additionally, because it holds onto water well, it is a particularly effective kind of mulch. If you need to stop beds drying out, improve the warmth, or otherwise have a reason to use mulch around your potatoes, mushroom compost is an excellent choice.

4) It Improves The Soil Structure

A lot of people plant potatoes to help them break up hard and clogging soils, because the potato plants are good at improving the soil structure. However, mushroom compost is similarly useful because it has an excellent structure.

If you mix the mushroom compost into your soil, you should find that it improves the structure and helps to de-compact the material. The best way to do this is to mix the mushroom compost into the soil during the winter so that it has time to mix with the soil and the nutrients can spread out for the potatoes.

5) It Contains Nitrogen

Mushroom compost contains some nitrogen, and this is critical for the growth of your potato plants. It releases this slowly, supplying your plants with what they need over a long period of time, and ensuring that they can put out plenty of healthy leaves.

These leaves will then give the plants the ability to photosynthesize, which will provide the energy needed for growing potatoes. This is a great way to get a good crop of root vegetables without spending a lot of money on expensive fertilizers each year.

6) It’s Sustainable

Because mushroom compost is a waste product, using it in your garden is an environmentally friendly way to farm. This waste might otherwise end up in landfills, which produces a lot of carbon dioxide and contributes to global warming.

Even if the mushroom compost would otherwise be disposed of responsibly, using it from your garden in the place of another product is certainly preferable because it is rather like a “recycled” material. Unlike virgin compost, which has to be made fresh, it has already had one use, so getting another out of it is an excellent way to reduce your global footprint.

What Are The Disadvantages Of Using Mushroom Compost For Potatoes?

Using mushroom compost has some drawbacks, however, and you should not try to plant potatoes in pure mushroom compost. Your plants will not grow, or will become sick and weedy, because the compost simply doesn’t contain enough nutrients to support them. Most of the goodness will have been taken out when it was used for mushrooms.

Some of the other drawbacks include:

  1. Mushroom compost is high in lime
  2. Mushroom compost contains a lot of salt
  3. It may contain peat

Although potatoes like mushroom compost, you should therefore be a little careful about using too much of it when growing them. These three drawbacks can be quite major, especially if you plan to use the potato bed for acid-loving plants at a later date.

1) It Is High In Lime

Mushroom compost tends to be highly alkaline. This isn’t a major problem for the actual growth of the potatoes, but it can cause scab disease, which affects the appearance of your potatoes on the outside.

On the whole, you can just rub the scab off before cooking and eating the potatoes, and there is no issue with consuming potatoes that have got scab. However, it doesn’t look very pretty, and it means extra work will be involved in preparing your potatoes to eat.

Additionally, the mushroom compost will make your soil more alkaline, which could mean that any future plantings are affected. Acid-loving vegetables include carrots, parsley, tomatoes, squashes, and more.

That means if you want to cycle your potato plants with other vegetables, mushroom compost can cause some long-term issues. You should therefore think carefully about the future of the bed before you add the compost to it.

2) It Contains A Lot Of Salt

Another drawback of mushroom compost is that it contains quite a lot of salt. Excessive salt levels can upset any kind of plant, including potatoes. That means you need to make sure you are using mushroom compost in controlled, limited quantities, rather than large amounts.

As long as you are using the mushroom compost as a soil amendment and light fertilizer, the salt shouldn’t be a problem, but if you plant in pure mushroom compost, you are unlikely to have success. The salt will kill the plants quickly.

Some people wash their mushroom compost to reduce the amount of salt in it, and this is an option if you want to use larger quantities of mushroom compost. However, this does involve extra work and you may find that you also wash the nutrients out of it at the same time, making it less valuable to the plants.

3) It May Contain Peat

Unfortunately, a lot of mushroom compost contains peat. Many environmentalists now are warning against using peat in your garden because it is so damaging to extract it from the environment, so gardeners are generally moving away from it.

However, this is a tricky issue to make any decisions about, because the compost has already been used by the industry before you, and it is better for the peat to have two uses rather than one. On the other hand, purchasing the compost supports the industry and could lead to further peat extraction.

The best way to solve this issue is to make sure you purchase mushroom compost that is peat-free. This is good for the environment because you are reusing a product, but you aren’t contributing to an industry that is taking peat from the planet.


Mushroom compost can be quite good for potatoes, and it offers valuable nutrients, good soil structure, and more. It is a reasonably cheap way to bulk up your vegetable beds and grow your plants, but it does contain quite a lot of lime, and you should be aware that it will make the vegetable beds more alkaline. This could affect future growing projects.

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