No, mushroom compost is generally not good for acid-loving plants.
Mushroom compost is often neutral to slightly alkaline, meaning it has a higher pH than is suitable for plants that thrive in acidic conditions. Acid-loving plants, also known as ericaceous plants, require soil with a lower pH (typically between 4.5 and 5.5) to properly absorb nutrients.
Based on the provided reference:
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.
Using mushroom compost around these plants can raise the soil pH, making it difficult for them to absorb essential nutrients, leading to poor growth, yellowing leaves (chlorosis), and potentially plant decline.
Why Avoid Mushroom Compost for Acid Lovers?
- pH Level: Mushroom compost typically has a pH range of 6.5 to 7.0 or even slightly higher after decomposition. This is too high for most acid-loving plants.
- Ingredients: The base materials for mushroom compost often include straw, hay, poultry litter, and sometimes lime or gypsum, which can contribute to its neutral or alkaline nature.
- Nutrient Lockout: In alkaline soil, nutrients like iron, manganese, and zinc become less available to plants, even if they are present in the soil. Acid-loving plants specifically rely on the availability of these nutrients in acidic conditions.
Plants to Avoid Using Mushroom Compost With
- Rhododendrons
- Azaleas
- Camellias
- Heathers
- Blueberries
- Some types of ferns
- Certain conifers (like Spruce and Fir)
Suitable Alternatives for Acid-Loving Plants
Instead of mushroom compost, consider using soil amendments that help maintain or lower soil pH and provide suitable organic matter:
- Peat moss: Excellent for lowering pH and improving soil structure.
- Pine bark fines or composted pine needles: Decompose slowly and contribute to acidity.
- Composted leaf mold (especially oak leaves): Can help create slightly acidic conditions.
- Specific ericaceous compost or potting mix: Formulated for the needs of acid-loving plants.
Comparison Table:
| Compost Type | Typical pH Level | Recommended for Acid-Loving Plants? |
|---|---|---|
| Mushroom Compost | Neutral to Alkaline (6.5+) | No |
| Peat Moss | Acidic (3.0-4.5) | Yes |
| Pine Bark Fines | Acidic (4.0-5.0) | Yes |
| Ericaceous Mix | Acidic (4.5-5.5) | Yes |
Using the correct type of compost or soil amendment is crucial for the health and vitality of acid-loving plants. Always check the pH suitability of a compost or soil mix before applying it to sensitive plants.
