Plants That Don’t Like Mushroom Compost

  • By: Sam Richards
  • Date: August 31, 2023
  • Time to read: 7 min.

Mushroom compost is derived from the organic matter used in the cultivation of mushrooms, commonly made up of straw, peat, gypsum, and other components. After mushrooms are harvested, the remaining substrate is recycled into this nutrient-packed compost. Its growing popularity in gardens can be attributed to its excellent water retention properties and rich nutrient profile, making it an appealing organic choice for amending soils. However, the diverse nature of plants means that while many thrive with the benefits of mushroom compost, others may not respond as favorably. Just as each plant has its unique sunlight and watering requirements, the soil medium can also play a pivotal role in its health and productivity. This article delves into the specificities of mushroom compost and highlights those plants that may not benefit from its application, providing insight for gardeners to make informed decisions.

What Makes Some Plants Dislike Mushroom Compost

Mushroom compost, with all its commendable attributes, is not a one-size-fits-all solution for every plant. Various factors determine why certain plants might not respond well to this compost:

  • High pH levels: At its core, mushroom compost tends to be more alkaline. This characteristic can increase the soil’s pH level, making it less acidic. While some plants thrive in alkaline conditions, others, especially those adapted to acidic soils, may struggle to absorb necessary nutrients in a higher pH environment.
  • High salinity: During the mushroom growing process, certain additives can result in compost with elevated salt levels. Plants that are sensitive to saline conditions may experience stunted growth, leaf burn, or other related stress symptoms when exposed to the high salinity of mushroom compost.
  • Presence of certain nutrients: Mushroom compost is nutrient-dense, and while many plants flourish with this added nutrition, others might find it overwhelming. The imbalance or overabundance of certain nutrients can be detrimental to some plants, potentially leading to nutrient burn or hindering the uptake of other essential nutrients.

Furthermore, the microbial environment of mushroom compost, while beneficial for many plants, might introduce specific fungi or bacteria not suitable for all plants. Understanding these intricacies is crucial to ensure that gardeners use mushroom compost where it can be most beneficial, and avoid it where it might be detrimental.

List of Plants That Dislike Mushroom Compost

While many plants relish the benefits of mushroom compost, a select group might face challenges with its application. Here’s a detailed look into some of these plants and the reasons for their sensitivity:

  1. Blueberries: As quintessential lovers of acidic soils, blueberries have specific pH requirements. They flourish in soils with a pH ranging from 4.5 to 5.5. The alkaline nature of mushroom compost can shift the soil pH, making it less conducive for blueberries to absorb vital nutrients, especially iron. This can lead to chlorosis, a condition where leaves turn yellow due to a lack of chlorophyll.
  2. Rhododendrons and Azaleas: These ornamental plants are not only known for their captivating blooms but also their preference for acidic soils. Their natural habitat often has a lower pH, and introducing mushroom compost can disrupt this balance, leading to less vibrant blooms and overall reduced vitality.
  3. Other acid-loving plants: Plants like camellias, conifers, and certain fern species thrive in more acidic environments. The use of mushroom compost can potentially disturb the soil’s pH, making it less hospitable for these plants.
  4. Plants sensitive to high salinity: Seedlings, in general, can be quite delicate, and some vegetable crops like beans and carrots can be adversely affected by the elevated salt levels found in some mushroom composts. These plants may display symptoms like stunted growth, browned leaf edges, or even seedling death.
  5. Plants prone to fungal diseases: While mushroom compost often suppresses certain pests and diseases, it might still retain fungi from the mushroom cultivation process. Plants already vulnerable to specific fungal infections could be at a heightened risk when introduced to this compost.

Awareness of these sensitivities ensures that gardeners can tailor their soil amendments to provide the most nurturing environment for every plant in their care.

Potential Harmful Effects of Mushroom Compost on Unsuitable Plants

When used for plants that aren’t ideally suited for mushroom compost, a range of adverse effects can manifest. Here’s a deeper dive into these repercussions:

  • Nutrient imbalances: One of the primary concerns with mushroom compost is its nutrient richness. While beneficial for most, some plants can suffer from an overload of certain nutrients. Excessive nutrients can lead to overly vigorous growth, which not only can weaken the plant but also make it a magnet for pests like aphids. Furthermore, an overabundance of specific nutrients might inhibit the uptake of others, resulting in nutrient deficiencies. For instance, an excessive amount of calcium can hinder the absorption of potassium.
  • Soil structure disturbances: Good soil structure is vital for plant health, promoting root growth and ensuring optimal water retention and drainage. While mushroom compost can enhance many soil types, it might also, in some circumstances, compact the soil. Compaction reduces aeration, which can restrict root growth, limit oxygen availability to roots, and even hinder water drainage, leading to waterlogged conditions.
  • Increased vulnerability to pests and diseases: Mushroom compost originates from a fungal cultivation environment. Even though the composting process can suppress many pathogens, some might persist. Plants already susceptible to certain fungal diseases might face a heightened risk when planted in mushroom compost. Moreover, if the compost hasn’t been thoroughly pasteurized or aged, there’s a chance it could introduce unwanted pests or diseases to the garden.
  • Alteration of soil pH: As previously mentioned, the alkaline nature of mushroom compost can raise the pH level of the soil. This shift is particularly concerning for plants that have evolved to thrive in acidic conditions. An increased pH can render some essential nutrients unavailable or less accessible to plants, leading to deficiencies.

By understanding and recognizing these potential issues, gardeners can make better-informed decisions, ensuring the longevity and health of their plants.

Alternatives to Mushroom Compost for Sensitive Plants

  1. Composted pine bark or pine needles: These can provide the acidic environment that many mushroom compost-sensitive plants prefer.
  2. Peat moss: It offers both water retention and acidity.
  3. Specific commercial soil mixes: Tailored for the needs of specific plants.
  4. Natural soil amendments: Like leaf mold or well-rotted manure, which can be less alkaline and better suited to some plants.

Tips for Using Mushroom Compost Successfully

While mushroom compost offers a plethora of benefits, leveraging its advantages requires strategic use. Here’s an in-depth guide to getting the most out of mushroom compost:

  • Testing soil pH before application: Before introducing any amendments to the garden, it’s essential to have a clear understanding of the soil’s current pH. Testing kits or meters, readily available at garden centers, can provide this information. By gauging the soil’s existing acidity or alkalinity, gardeners can make informed decisions on how much mushroom compost to use, or if it’s suitable at all.
  • Mixing mushroom compost with other organic materials: Combining mushroom compost with other compost types or organic matter can create a more balanced soil amendment. For instance, blending it with pine needle compost or leaf mold can help counteract its alkalinity, making it more appropriate for acid-loving plants.
  • Monitoring plant health post-application: Observing plants after applying mushroom compost is critical. Signs such as yellowing leaves, stunted growth, or poor flowering can indicate potential problems. Early detection allows gardeners to intervene, perhaps by adjusting watering patterns, introducing other soil amendments, or seeking solutions for potential pest and disease issues.
  • Regular watering and ensuring good drainage: Proper hydration aids in distributing the nutrients from the compost evenly through the soil. It also helps to leach out any excess salts that might be present. However, it’s just as important to ensure that the garden bed or pot has adequate drainage. This prevents waterlogging, which, when combined with a rich medium like mushroom compost, can create a breeding ground for root rot and other fungal diseases.
  • Ageing the compost before use: Fresh mushroom compost can be too ‘hot’ or rich for some plants, especially young ones. Allowing the compost to age or ‘mellow out’ for several months can decrease its intensity, making it gentler on plants when applied.
  • Being wary of over-application: Moderation is key. While the nutrient richness of mushroom compost is one of its primary advantages, applying too much can overwhelm plants. It’s always advisable to follow guidelines or seek expert advice on appropriate application rates for specific plants or garden scenarios.

By following these guidelines, gardeners can harness the full potential of mushroom compost, ensuring a healthy, thriving garden environment.


The world of gardening is richly diverse, just like the myriad plants that call our gardens home. Each plant, with its unique requirements, urges us to take a nuanced approach, especially when it comes to soil amendments like mushroom compost. While this compost brings an array of benefits—from nutrient enrichment to improved soil structure—it isn’t universally suitable. As gardeners, our primary goal is to create an environment where our plants can flourish, reaching their full potential in growth, bloom, and health.

Understanding the intricacies of mushroom compost, both its strengths and limitations is a testament to the delicate balance required in gardening. Every decision, from the type of soil amendment to the watering frequency, can shape the destiny of a garden. The tale of mushroom compost underscores the broader narrative of gardening itself: the need for observation, adaptability, and a keen sense of care. As we cultivate our gardens, we’re reminded that success often lies in the details, in the harmonious balance of all elements working in tandem. Through informed choices, we can craft garden spaces that not only look stunning but also resonate with the rhythms of nature.

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