Happy frog cavern culture fertilizer is a proprietary blend of bat and seabird guano, rock phosphate, and soil microbes specially formulated to deliver the nutrition necessary for flowering and bud development. Mycorrhizal fungi are included to help increase root efficiency, which may enhance nutrient uptake and water absorption. experience the tried and true successes of our ancestors with cavern culture in your own backyard. Guanos have been used for centuries as fertilizers for all kinds of plants. Comes in 4 pound bag.