Organic Vocabulary: Bat Guano

Bat guano is the dried droppings of bats, collected from cave floors. High-quality guano can have an NPK analysis of 10-2-1, making it one of the best ways to add large amounts of nitrogen to the garden without the use of chemicals. The high nitrogen content produces deep-green, vigorous foliage. Guano also contains micronutrients often absent in soils and soil mixes and lacking in synthetic fertilizers.

Use guano in a dry powder form at the recommended package rate, applying it to the root zone at seeding or planting time; top-dressing is also effective. As plants develop, guano can also be blended into a liquid foliar feed at a rate of 5 mL (1 tsp.) of powder per litre (quart) of water and applied every two weeks. Guano blended with worm castings, manures and compost creates well-textured soil full of beneficial organisms, minerals and vitamins.

If your plants are stunted or the leaves are yellow, amend your soil with bat guano; its high nitrogen may be just what your plants and soil need.