Excellent response of cranberries to 12-12-2.5 Seabird Guano. By contrast DeMoranville, UM Experimental Station found hydrolyzed fish the best organic fertilizer she tested. The Seabird Guano results in better growth and fruiting in our bog than the hydrolyzed fish.
Caution, Cranberries take up the ammonial form of nitrogen, not nitrate. Most other plants take up Nitrate forms of nitrogen and then convert it to ammonial forms. So try it befor going all out with it.