Mushroom compost is a popular soil amendment for gardeners looking to add nutrients and organic matter to their soil. But when it comes to growing potatoes specifically is mushroom compost a helpful addition or not? In this in-depth article we’ll examine the pros and cons of using mushroom compost for potatoes.
What is Mushroom Compost?
Mushroom compost, also called “spent mushroom substrate,” is made from the leftover growing medium after mushrooms are harvested commercially. The original ingredients vary by manufacturer but often include straw, poultry manure, gypsum, peat moss, and meal from corn, cottonseed, or cocoa shells.
After the mushroom crop is harvested, the remaining compost is pasteurized to kill off any fungi or bacteria. This destroys lingering pathogens while leaving beneficial microorganisms. The finished compost contains a diverse blend of organic materials and nutrients.
Potential Benefits of Mushroom Compost for Potatoes
When used properly, mushroom compost offers some potential upsides for growing hearty potato crops:
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Organic matter – The compost introduces beneficial organic materials like straw, peat, and manure This can improve soil structure, aeration, and water retention
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Nutrients – Mushroom compost provides a range of macronutrients like nitrogen, phosphorus, and potassium from the manure and organic ingredients used. This helps feed soil microbes and potato plants.
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Soil life – The compost contains microorganisms like beneficial bacteria and fungi. These help break down organic matter and cycle nutrients for plant availability.
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Moisture retention – The peat, straw, and other organic materials in mushroom compost act like a sponge to hold moisture. Potatoes need consistent soil moisture.
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Weed suppression – Spread as mulch, mushroom compost can block light and smother weed seed germination. Less weeding means less root/tuber damage.
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pH level – Mushroom compost usually has a neutral to slightly alkaline pH around 6.5-7.5. This is the preferred pH for potatoes, counteracting acidic soils.
Potential Drawbacks of Using Mushroom Compost on Potatoes
However, there are also some possible disadvantages to keep in mind:
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Salt content – Some mushroom compost contains high salt content from the manure and other amendments used. Excess salts can damage plant roots.
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Depleted nutrients – Since it already grew mushrooms, nitrogen and other nutrients can be depleted in mushroom compost. Additional fertilizer may be needed to replenish.
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Fast drying – The added organic matter can lead mushroom compost to dry out quickly. More frequent irrigation may be required in hot/dry weather.
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Weed seeds – Lower quality mushroom compost may harbor viable weed seeds that will sprout unwanted plants.
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Mold issues – If not fully pasteurized, active mold and fungi can remain in mushroom compost and spread issues like blight.
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Cost – Purchased mushroom compost is typically more expensive than making your own compost at home.
Best Practices for Using Mushroom Compost on Potatoes
To maximize the benefits while avoiding potential problems, follow these tips:
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Test new mushroom compost for pH, salt content, and pathogens before using in your garden.
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Mix compost with garden soil or coconut coir at a 1:1 ratio for better drainage and nutrient balance.
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Till compost into potato rows, not directly on seed potatoes which can burn tender sprouts.
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Water newly planted potatoes daily until sprouts emerge to account for moisture loss through compost.
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Side dress growing potato plants halfway through the season with extra compost as a moisture retaining mulch.
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Avoid mushroom compost sources that result in disease or fungi issues. Discontinue their use.
The Verdict: Can Mushroom Compost Help Potatoes Thrive?
When used properly by testing its quality first, mushroom compost can be a beneficial addition for enriching and nourishing potato crop soils. Its moisture retention and organic matter are useful, but should be balanced with extra fertilizer and close irrigation to prevent deficiencies. With smart practices, mushroom compost can absolutely help your potatoes thrive! But farmers should always assess each new batch of compost for quality and blend accordingly into their beds or rows.
Sit Back & Let Your Potatoes Grow
Potatoes do take quite a long time to form. Remember they have to literally multiply themselves underground. I generally plant my potatoes in April and dont harvest them until August, which is about 90 to 100 days after planting.
For culinary purposes, you can classify potatoes as vegetables. Thats a really broad category though, and it doesnt tell us gardeners very much about how to actually grow potatoes.
So for gardening purposes, were going to classify potatoes as a root crop. Potatoes are technically tubers, meaning theyre fleshy underground stems that grow new plants through buds. Similar to roots, tubers store nutrients for the entire potato plant.
I lump potatoes and sweet potatoes (which are tuberous roots) in with roots like carrots, beets, and radishes for one obvious reason: The part we want to eat grows underground. But also, knowing how to grow one goes a long way in helping you know how to grow the others.
Prepare the Space for Your Potato Plants
Potatoes prefer more acidic dirt. You can buy acidifiers to amend your garden soil, but I’ve found that potatoes planted in compost grow totally tubular, as well. Add about two to three inches of compost in the trench. I use Espoma’s Organic Mushroom Compost. This way, when potatoes are first planted, theyll feel like theyre in 100 percent compost, which will give them a great start. Shop Gardening Books
Is Mushroom Compost Good For A Garden Or Should You Avoid It?
FAQ
Can I use mushroom compost on potatoes?
Prepare the Space for Your Potato Plants
Add about two to three inches of compost in the trench. I use Espoma’s Organic Mushroom Compost. This way, when potatoes are first planted, they’ll feel like they’re in 100 percent compost, which will give them a great start.
What is the best compost for potatoes?
Which plants do not like mushroom compost?
4. Do not apply hot compost (meaning mushroom compost or other nutrient rich sources) to woodland (eg ferns) or silver-leaved plants (lavender), because they are not used to having that level of nitrogen shock. Instead, use leaf litter for the woodland.
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.