how to use worm castings in potted plants

How to Use Worm Castings in Potted Plants

Worm castings are an incredibly beneficial soil amendment for potted plants, due to their high concentration of nutrients and microbial activity. Though not appropriate for all plants, here is a quick guide to incorporating worm castings into your potted plant mix.

What are Worm Castings?

Worm castings are made from the nutrient-rich waste of composting worms, which includes worm manure, worm cocoons, and soil particles. This material is high in beneficial bacteria, enzymes, humus, Macro-nutrients like nitrogen and phosphorus, and micronutrients like calcium and magnesium.

Benefits of Worm Castings for Potted Plants

Worm castings provide a gentle, sustained release of nutrients, which is especially beneficial for slower growing and more delicate plants. In addition, the bacteria and enzymes produced within the castings actively work to improve the soil structure of your potted plants.

Types of Plants Suited to Worm Castings

When it comes to incorporating worm castings into potted plants, it’s important to consider the type of plants you have. Here are some types of plants which benefit from worm castings:

  • Vegetables and Herbs: Many varieties of vegetables, herbs, and even edible flowers do well in soil which has been supplemented with worm castings.
  • Tropicals: Many indoor and tropical plants benefit from the sustained release of nutrients and microbes available in worm castings.
  • Container Gardens: Any potted plants such as container gardens benefit greatly from worm castings.

How to Add Worm Castings to Potted Plants

The amount of worm castings you use is determined by the type and size of the potted plant. For most plants, a good guide is to add around 10% of worm castings to your soil mix. It’s usually best to blend the castings in evenly with the potting soil, for best results.

It’s important to note that you should avoid mixing more than 25% worm castings into potted plants, as you can end up with a nutrient imbalance which will damage your plants. Additionally, it’s best to avoid mixing your castings with fertilizers, as this can also cause issues with nutrient levels.


Worm castings are an excellent way to improve the soil around your potted plants. They provide a steady release of nutrients, in addition to a host of beneficial bacteria and enzymes. Just remember to take into account the type of plant and the amount of castings you’re using, and you’re sure to have success in no time!

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