If you are not ready to start your mushroom kit, keep it in the fridge until you are ready, (or it will keep growing!). Pink oysters need to be used right away as they can not be stored in a fridge. Shiitake grow bag We supply many commercial farms with this exact type of Shiitake block so you can be sure that you are getting a top-quality product Grow Lots of fresh Shiitake mushrooms with this easy kit Type: choice edible, medicinal usage and compounds, research Characteristics: Light Tan & Dark Brown Aussie mushroom co2 bags are made fresh to order each day. We order as needed so they are super fresh and in activated. Once activated the bag will begin to fill and puff up forces co2 through the one-way valve. Once bag inflates and activated, they will produce high grade co2 for approximately 6mths. To keep them fresher you can stop activation by keeping them refrigerated