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As a gardener, I’m always looking for ways to provide the best nutrients for optimal growth of my plants. When it comes to growing potatoes, one soil amendment I often consider is mushroom compost. But do potatoes really thrive when grown in this dark, rich material? Let’s take an in-depth look at the pros and cons of using mushroom compost for potatoes.
What is Mushroom Compost?
Mushroom compost, also called “spent mushroom substrate,” is a byproduct of commercial mushroom production. After mushrooms are harvested, the remaining growing medium is pasteurized to kill any lingering fungi and bacteria. This results in a compost that can be used as a soil conditioner.
Ingredients vary between mushroom farms but typically include:
- Straw
- Poultry manure
- Gypsum
- Peat moss
- Corn cobs
- Cottonseed meal
- Cocoa shells
While this nutrient-rich blend provides an excellent growth medium for mushrooms, how does it work for growing our potato crops? Let’s look at the potential benefits and drawbacks.
Potential Benefits of Using Mushroom Compost for Potatoes
There are some clear advantages to using mushroom compost when growing potatoes
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Organic matter: The compost introduces beneficial organic materials into the soil, improving structure and water retention.
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Nutrients Mushroom compost contains nitrogen phosphorus potassium and micronutrients from the manure and other ingredients. This helps feed soil microbes and crops.
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Soil life: The compost inoculates soil with helpful microorganisms like bacteria and fungi which break down organic matter into plant-available nutrients.
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Water holding capacity: The peat and other organic parts of mushroom compost act as a sponge to hold moisture. Potatoes need consistent soil moisture.
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Weed suppression: As a mulch, mushroom compost can block light to prevent weed seeds from germinating. Less weeding means less damage to potato roots and tubers.
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pH level: Mushroom compost tends to have a neutral to slightly alkaline pH, which potatoes prefer. It can counteract acidic soil conditions.
Potential Drawbacks of Using Mushroom Compost on Potatoes
However, there are also some potential disadvantages to be aware of when using mushroom compost for potatoes:
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Salt content: Some compost can have high salt levels from the ingredients used. This can burn plant roots if excessive amounts are applied.
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Depleted nutrients: Since it has already grown mushrooms, some nutrients like nitrogen are used up in the initial growth. Fertilizer may be needed to replenish the supply for potatoes.
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Water demands: The higher organic matter content can lead to faster drying out during hot, dry periods. More frequent irrigation may be required.
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Weed seeds: Lower quality mushroom compost may contain viable weed seeds that will sprout unwanted plants.
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Mold: If incompletely pasteurized, active fungi and mold can remain. This can spread blight-causing organisms to the potatoes.
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Cost: Purchased mushroom compost can be more expensive than homemade compost.
Best Practices for Using Mushroom Compost on Potatoes
To maximize the benefits and avoid potential downsides when using mushroom compost for potatoes, follow these tips:
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Test mushroom compost pH and salt levels before use.
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Add fertilizers like alfalfa meal to supplement nutrients if needed.
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Mix compost 50/50 with garden soil or coconut coir to improve drainage.
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Add compost only to planting furrows, not directly on potato seed pieces.
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Water newly planted potatoes daily until sprouts emerge.
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Side dress growing plants with extra compost as a nutritious mulch midway through the growing season.
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Discontinue use of any compost sources that promote fungal issues.
The Verdict on Mushroom Compost for Potatoes
When used properly, mushroom compost offers clear soil health and moisture retention benefits for potatoes. While it is not a complete fertilizer on its own, mushroom compost is an excellent amendment for nourishing potatoes when paired with additional nutritional inputs. Test any new sources for quality and blend into high-quality potting mixes for best results. With a little fine-tuning, mushroom compost can be a real winner for your potato patch!
How to Plant Potatoes in Containers
Planting in containers goes a lot faster because you dont have to dig in the ground.
Make sure youre using potatoes that are already starting to chit, or send out their first growth. Place the seed potatoes on top of the soil, with the potato eyes facing up. Space them at least 6 inches apart. I planted six potatoes around the perimeter and one in the middle of my whiskey barrel.
Add some more compost so that the seed potatoes are covered. Leave about 8 to 10 inches of your container empty. That way, you can come in and add more compost as your potatoes grow. Water your potatoes in.
Learn more about planting potatoes.
When to Plant Potatoes in Your Climate
You can plant your potatoes as early as 15 to 30 days before your last frost of the season. (Dont worry if you get another frost. The soil will protect your potatoes.) This way, your potato plants will be up and growing before it gets too hot.
If youre planting fall potatoes in a warm climate, check the days to harvest for the type youre growing and make sure you have at least that long before your first expected frost. Youll want to pull in your harvest before the cold sets in.
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Is Mushroom Compost Good For A Garden Or Should You Avoid It?
FAQ
What type of compost is best for potatoes?
When it comes to compost, a well-balanced compost that is rich in nutrients and has a neutral pH is generally the best choice for growing potatoes.Jun 28, 2016
What plants do not like mushroom compost?
When should you not use mushroom compost?
Mushroom compost use should be avoided where ericaceous plants such as rhododendrons, camellias, azaleas and heathers are being grown, as these plants need acidic growing conditions and are chalk-hating.
What vegetables grow well in mushroom compost?
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Rich in Nutrients:Mushroom compost is a nutrient-rich soil amendment, providing essential elements for plant growth and development, according to Daisy’s Garden Supplies.
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Increased Yield and Growth:The nutrients in mushroom compost can help stimulate growth, increase yield, and enhance the taste of your homegrown produce, says Daisy’s Garden Supplies.
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Calcium Enrichment:Mushroom compost contains more calcium than regular compost, which is beneficial for plants like tomatoes and peppers that require calcium for strong cell walls.
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Slightly Alkaline pH:Mushroom compost has a slightly alkaline pH (6.5-7), which is ideal for many vegetable crops and helps prevent clubroot disease in brassicas, according to the RHS.
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Direct Seeding:Some plants, like radishes, carrots, and herbs, can even be directly seeded into mushroom compost, according to Full Circle Mushroom Compost.
Is mushroom compost good for potatoes?
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.
How do you grow potatoes with mushroom compost?
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. Mushroom compost contains some nitrogen, and this is critical for the growth of your potato plants.
Does mushroom compost scab on 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.
Is compost good for potatoes?
Because they are heavy feeders, compost makes a great growing medium for potatoes. Compost is very high in nutrition, and is therefore generally used as a soil amendment, since most plants have average vitamin and mineral requirements. Plants in the Solanaceae family, however, need much higher quantities.
Is mushroom compost good for vegetables?
Mushroom compost is excellent for a variety of plants, including most garden vegetables. It provides vegetables with a light application of the nutrients they need to thrive and produce a bountiful harvest. It also helps the soil retain water, which is especially great for nutrient absorption.
Can You reuse potato compost?
You can reuse potato compost. Compost that’s been buried under ground with the seed potato, will break down and become reused in the soil around it. Bags of compost that have had potatoes growing in them, can be reused by just spreading it over soil and working it in.