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One way you can use earthworm

One way you can use earthworm casts is to top dress your soil with a 1/2-inch to 1-inch layer of earthworm casts. For potted plants, use about 1/3 casts to 2/3 potting soil.

You can also just place earthworm casts alongside your plants. This is helpful if your plants are in rows.

I hope this helps!