Hydrated Lime

Low magnesium hydrated horticultural lime, otherwise known as calcium hydroxide. Suitable for cold water lime pasteurisation of straw for aggressive mushroom strains like most oyster varieties.

Note that this is NOT your typical builders lime/garden lime/dolomite lime which contains high levels of magnesium lime which will kill mycelium. We use this premium, low-magnesium lime in our own commercial operation to pasteurise straw when growing oyster mushrooms, so can vouch for it’s effectiveness. Don’t settle for inferior lime, as you’ll be very disappointed.

Cold water pasteurisation using lime is a low energy, cost effective method of pasteurising straw or other substrates ready for colonisation.

The added lime increases the PH of your soak solution to 11 – 13 PH, which is extremely alkaline and kills off bad competitor organisms.

Due to the high PH, we recommend wearing correct protective gear when handling hydrated lime as it can irritate the skin, eyes and lungs if inhaled. Wear glove, goggles and a mask and handle carefully.

The water solubility of lime is between 1.89 – 1.73 g/L (0°C – 20 °C). For example: if you are cold soaking straw in a 50 gal drum, for 200 litres of water, you’ll need approx. 350g of lime. Leave to soak for 10-24 hours for correct pasteurisation.

During the pasteurisation, the PH of the lime solution will normally drop to 6-8. This is normal but can vary. If your resulting water has a PH of more than 8, consider using citric acid to neutralise the water before disposal.

Wood ash can also be used for pasteurisation of straw, or used in combination with the lime soak to add additional nutrients to the substrate.