Amanita cultivation in a lab environment has always been a frustrating prospect due to the symbiotic relationship of this mushroom to its host trees, most of which are Birch trees that occur naturally in the wild.y own observations (I’ve yet to actually learn this) of Amanita growth suggest that mycelia growth takes place primarily throughout the Spring and Summer months and is highly dependent on rain and soil moisture preceding the Fall fruiting. If the season is dry just water your mushroom garden every few days.