Seedlings: Use up to 20 percent worm castings in your potting mix. More than 20 percent will not harm plants, but it won’t offer much additional benefit.
Vegetables and annuals: Side dress with about ½ cup of worm castings per plant as needed.
Transplants: Provide 1 inch of worm castings in planting hole before placing plant.
Potted plants: Mix 1 inch of worm castings with top of soil around base of plants as needed.
Trees and shrubs: Mix 1 inch of worm castings with top of soil around base of plants every month during growing season.