Bloom BBloom B is a fine powder that mixes consistently every time regardless of the reservoir size. Unlike other soluble lines that sell large prilled inputs, we mix all inputs, grind, and then mix again to ensure every grower gets the benefits of soluble fertilizers. Fully soluble and clean. Bloom A and Bloom B are used together from day 21 of flower until 2 weeks prior to chop. Cropsalt was the first line to talk about the importance of switching to bloom