For an idea of how many earthworms your garden could happily house, consider these numbers: Healthy soil can contain about 1.5 million worms per acre. The more the merrier in most garden plots, given that their castings contain 10 times the amount of nutrients and minerals as were in the plant debris they feasted on. That adds up to rich soil in which plants thrive. To estimate how many earthworms you already have, dig a hole 8-10 deep by one foot wide. Count the worms you find in the dirt you remove. Score your soil using these figures: More than 10 worms = robust soil, 6 to 10 = moderately healthy soil and 5 or less = soil needs improvement. If its time to replenish your supply with Encapsulated Earthworm Cocoons, we've done the math for you. Use at least one cocoon per square foot to reintroduce earthworms--and their numerous benefits--into your soil.