Gypsum speeds up mushroom growth in sawdust mix

Gypsum container beside Chestnut mushrooms

Gypsum is a mineral that helps speed up the mushroom growing process in small amounts.

A teaspoon of gypsum is added to the supplemented sawdust mix, which also includes hardwood sawdust pellets, wheat bran and water. We use this mix for five types of mushrooms, including the Lion’s Mane, Chestnut and Shiitake mushrooms.

Gypsum has been found to shorten the time it takes for the mycelium to grow throughout the substrate, according to researchers at the University of Putra Malaysia. That means it’s quicker for the spores to grow throughout the growing block and start to grow mushrooms.

The researchers tested different alkaline materials, such as gypsum, agricultural lime and zeolite, another type of mineral. Only one percent of each mix included an alkaline material. They grew Italian Oyster mushrooms, which we choose to grow using hardwood sawdust and soybean hulls because of their protein content.

It took 30 days for the mycelium in the gypsum mix to spread throughout the block – 18 days quicker than the lime mix and 20 days faster than the zeolite mix. Primordia, or baby mushrooms, started growing the quickest on gypsum mix as well.

Which mushrooms grow in supplemented sawdust with gypsum? Lion's Mane, Black King Oyster, Chestnut, Shiitake and Reishi.

Gypsum is supposed to help the ingredients mix in the bag without clumping. That makes it better for the mycelium to get the nutrients it needs in the bag to continue spreading. Gypsum also adds calcium and sulphur, which are supposed to neutralize the pH levels of the block, according to researchers in Pakistan. Mushrooms prefer slightly acidic pH levels, but increasing the pH with the gypsum helps prevent bacterial growth.

If you’re interested in trying to grow mushrooms in a mix with gypsum, take a look at our JCB Gourmet Mushrooms Grow Kits on our website. Every mushroom except for the Oyster mushrooms uses the supplemented sawdust mix, which includes gypsum powder. Black King Oyster mushrooms also grow on the supplemented sawdust mix.

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