Hydrated Lime For Mushroom Substrate Pasteurisation

Our Hydrated Lime (Calcium Hydroxide) also known as builders lime is a valuable tool for mushroom growers seeking a fast and effective low-tech / no heat pasteurisation method. Ideal for use with straw, sugarcane bagasse, or other cellulose-rich substrates, hydrated lime raises the pH of the water dramatically, creating an environment that eliminates harmful microbes while preserving beneficial structure for mushroom colonisation.

Works well for pasteurising oyster mushroom substrate supplementing with fresh coffee grounds or even up to 30% soy hull supplementation.

1 - Chop and pre-soak your substrate material (e.g., straw or bagasse).
2- Mix hydrated lime into clean water at a rate of approximately 1 gram per litre (adjust slightly based on your local water pH).
3- Fully submerge the substrate in the lime water solution for 12–24 hours, ensuring it’s weighed down to stay below the surface.
4- Drain thoroughly—do not rinse—then pack the substrate into grow bags or containers and inoculate with mushroom spawn.

This method is especially popular for growing oyster and other fast-colonising species that thrive on high-pH treated substrates.

250g – Ideal for trials or hobby setups, treat up to 250L of water
500g – Small batch growing, treat up to 500L of water
1KG & 2KG – Great for ongoing or commercial use, treat between 1000-2000L of water

• We ship from Tamborine Mountain, QLD using either AusPost or Aramex
• Fast dispatch within 1 business day (excluding Fridays) with express post options available