Calcium Hydroxide Lime substrate Pasteurization

NZD $7.00$15.00


Calcium Hydroxide Lime/Hydrated Lime (Ca(OH)2) for Substrate Cold Pasteurization in Mushroom Growing

This product, high in Calcium and low in Magnesium, is commonly known as Calcium Hydroxide, Slaked Lime, or Builder’s Lime (Ca(OH)2). It is ideal for cold water pasteurization of your substrate due to its ability to drastically alter the pH, effectively eliminating contaminants.

Cold Pasteurization Insight: While pasteurization kills live organisms, it does not destroy their spores. Therefore, we recommend employing boiling water for a super pasteurization effect. Post-pasteurization provides a two-week window before susceptibility to contamination increases. Rapid substrate colonization within this timeframe is crucial, as a densely populated mycelium provides a strong defense against sporulating contaminants. With this technique, a higher grain-to-substrate ratio is advised; while typically only 5-10% spawn is added to the substrate, we suggest a minimum of 20-25% when using pasteurization.

Product Benefits:

  • Eliminates the need for autoclave/pressure cooker processes in mushroom cultivation.
  • Supplements the mycelium with calcium, enhancing growth speed and vigor.
  • Ideally used with low-nutritional substrates such as sugarcane mulch, straw, coco coir, and vermiculite.

Your Purchase Includes:

  • 50gm or 300gm of Hydrated Lime (Ca(OH)2)


  • Chemical Name: Calcium Dihydroxide
  • Chemical Formula: Ca(OH)2
  • Color: White
  • Appearance: Powder
  • Odor: Odorless
  • pH: 12.4 (saturated solution at 20˚C)
  • Purity: 95%
  • Solubility: Soluble in water
  • Other Names: Hydrated Lime, Slaked Lime, Pickling Lime

Instructions: Important: Always use protective gear such as a mask, gloves, and eye protection.

  1. Soak your substrate in cold or hot water treated with Hydrated Lime for 3-12 hours.
  2. Drain water and inoculate with your mushroom grain spawn.


  • Use specified water amounts to avoid the need to drain excess.
  • For every 1 Kg of straw, use 4 liters of water.
  • For every liter of water, add 5 gms of Lime.
  • Grain Spawn: Inoculate with at least 25% grain spawn (1 part grain spawn to 4 parts substrate) to accelerate colonization and minimize contamination risks.

Additional Tools: Measure pH levels post-Lime addition with our PH strips available in our store.

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