Calcium Hydroxide Lime substrate Pasteurization

$7.00$15.00 inc. GST


Calcium Hydroxide Lime/ Hydrated Lime (Ca(OH)2) for substrate cold pasteurization technique mushroom growing

This product is Naturally High in Calcium and low in Magnesium. It is also called Calcium Hydroxide, Slaked Lime, and Builder’s Lime. Its chemical formula is Ca(OH)2. This hydrated Lime is perfect for cold water pasteurization for your substrate. That is because the Lime will change the PH of the medium drastically, leading to all contaminants dying.

Pasteurization only kills living organisms, not their spores, so we recommend using boiling water instead of cold water with this technique. This method is called super pasteurization.

With pasteurization, you dispose of a 2-week window before it is prone to contamination. Ensuring complete substrate colonization within 2 weeks will provide a robust defense mechanism for the mycelium before contaminants start to sporulate. For instance, we recommend a higher grain-to-substrate ratio with this technique. Typically, you would only be required to add 5-10% spawn to your substrate. However, we recommend a 20-25% minimum spawn ratio when using pasteurization.

The key feature of this product is that it removes the autoclave/pressure cooker process when growing mushrooms. Moreover, it will add much-needed calcium to the mycelium, enhancing the speed of growth and vigor.

It is best to use a low nutritional substrate when using this method. It includes sugarcane mulch, straw, coco coir, vermiculite, etc.


Your purchase includes:

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


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



Important: Use proper protective equipment such as a mask, gloves, and eye protection.

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


Using the amount of water specified is recommended so you do not have to drain any excess water.

  • For every 1 Kg of straw, you may need 4 Liters of water.
  • For every liter of water, you would need 5 gms of Lime.
  • Grain Spawn: We recommend inoculating with at least 25% grain spawn (1 part Grain spawn: 4 parts substrate). As a result, it will shorten colonization, reducing the chances for other contaminants to grow and thrive.

If you intend to measure the PH levels on your substrate after adding Lime, we offer PH strips in our store.

Get everything you need to Grow Mushrooms in Monotubs and Grow Mushroom in Buckets in Our Store

Shipping Cost – The product is shipped via Australia Post using Express Post service for $5.80. If multiple items are in the cart with varying shipping costs, only the highest shipping cost for a product in the cart will be charged.

Handling time- This product has 0 days handling time and is shipped the same day if ordered before 12 pm. However, it’s important to note that if other items are in your cart, the handling time may vary based on the handling time associated with those additional items. Handling time is not guaranteed during the busy holiday period.

Shipping time- Australia Post guarantees express post is delivered the next day in metro regions of Capital cities, but give it anywhere from 1-3 days for this package to reach you. Shipping times are not guaranteed during the busy holiday period.


Please enter your email address to receive your Quote.

Join Waitlist We will inform you when the product arrives in stock. Please leave your valid email address below.
    Your Cart
    Your cart is emptyReturn to Shop
      Calculate Shipping
      Apply Coupon