How To Use Worm Castings in Your Potted Plants?

If you keep a garden outside or have a compost pile, you can run into worm castings. Did you know you can collect and use them in your potted plants? Doing so offers your houseplants plenty of benefits, so you may want to try it.

You can use worm castings in your potted plants in several ways. Most gardeners use them as an organic, slow-release fertilizer. You can also use them as a top dressing or potting mix, and your plants are sure to love them.

This article will go over using worm castings and their benefits for potted plants. You’ll be an expert in no time, so let’s begin!

1. Collect the Worm Castings

You can find worm castings anywhere that you’d find worms. For example, they will be in your garden and compost pile. However, collecting them from those areas can be difficult, and you’re removing the nutrients that the castings provide.

The most efficient way to collect worm castings is to start a vermicomposting bin. It’s a simple process and won’t cost you more than a few bucks to start.

You will need:

  • A five-gallon (19 L) bucket or another large plastic container
  • A drill
  • Newspaper
  • Food waste, the same organic materials that you’d use in a compost bin

Once you have all of your materials, follow these steps:

  1. Clean the container and flip it over. 
  2. Drill several holes into its bottom. 
  3. Add a layer of food waste to the inside of the bin.
  4. Tear apart the newspaper into many smaller strips, then wet them. They should be moist, not soaked or dripping water.
  5. Put half of the strips in the bin.
  6. Gently add your worms.
  7. Place the rest of the wet newspaper over them.
  8. Set the container aside somewhere you won’t forget about it. It should be raised to allow for drainage out the bottom.
  9. Add more food waste to the container every two weeks. Try not to add a lot at once. 

Alternatively, you can use readily available worm composters, like the Essential Living Composter (available on It’s efficiently designed to process worm castings and worm tea while containing the odor. This allows the product to be kept indoors all year round. It also comes in various colors to match your home’s interior.

After several weeks, a layer of worm castings will form under the newspaper. The population increases as you keep feeding the worms, leading to more castings.

From there, collecting the castings is simple. Lay out a plastic tarp and pour the bin out on it. Sort the materials, putting the worms, newspaper, and food waste back into the bin. You should be left with the worm castings, the brown dirt-like layer at the bottom of your container.

What Are Worm Castings?

Worm castings are the waste worms produce, therefore considered manure or organic material. As the castings break down, they deposit various nutrients into the soil, which your plants need to grow. They’re organic and safe for you to handle.

Since your pots shouldn’t have any worms in them, you can add worm castings to the potting mix to boost their nutrient content. Plus, your potted plants need fertilizer every so often anyway since nutrients don’t naturally return to potting soil.

For those reasons, worm castings make the perfect natural fertilizers for houseplants.

2. Use the Castings as a Top Dressing

Many gardeners like to use their worm castings as a top dressing. It’s convenient because you don’t need to mix the castings into the soil and the plants still get plenty of nutrients from the castings.

To do this, simply sprinkle some of the castings over the potted plant’s soil, then water the plant. It’s essential to water the plant immediately after applying the castings since it helps push them into the soil.

The top dressing will eventually break down and incorporate the nutrients into the soil, making them available for the plant roots to absorb.

You also don’t need to apply a top dressing very often. Most gardeners do this every three to four months and get good results. This is mainly because worm castings work like slow-release fertilizers.

3. Use the Castings in Your Potting Mix

You can also use the worm castings in your potting mix. However, you can only do this before adding any plants to the pot.

It’s an easy process and provides your potted plants with nutrients for a very long time. Here’s what you can do:

  1. Spread your potting mix out in a wide container or on a tarp.
  2. Sprinkle several handfuls of worm castings on the soil. 
  3. Combine the soil and castings as well as possible. You want an even distribution of both.
  4. Collect the potting mix and use it as usual.

This method also comes with several benefits. Your plants will have constant access to the nutrients from the castings. Plus, the castings will be much closer to their roots, making it easier for them to absorb the nutrients.

Adding worm castings to your potting mix is also excellent for soil aeration. It helps prevent the soil from compacting, giving your plants better soil conditions. 

4. Use the Castings During Transplanting

You can use the worm castings when transplanting plants to new pots to help prevent shock. Before moving the plant to its new home, you’ll need to combine the castings with the fresh potting mix using the steps above. Then, you can finish repotting the plant as usual.

The nutrients from the worm casting and the frequent watering can encourage your plant to spread its roots in the new pot. As the roots spread, your plant becomes more established.

Plus, your plant won’t lose access to essential nutrients after being transplanted, which can significantly reduce the effects of transplant shock.

And speaking of transplanting, did you know that one pot can potentially hold different flowers simultaneously? Yes, it can make things a bit crowded, and the plants will compete for nutrients, which is where worm casting can come in handy. To know more about raising different flowers in the same spot, check out my article on this topic: Can You Plant Different Flowers in the Same Spots?

5. Make Worm Tea for Your Plants

Lastly, you can prepare worm tea for your potted plants, which is very similar to a liquid fertilizer. Since your plants won’t have to wait for the castings to break down, they can absorb nutrients from the tea immediately.

It’s easy to make. Here’s how:

  1. Combine one part worm castings and three parts water in a large container. Five-gallon (19 L) buckets work great.
  2. Allow the mixture to sit for 24 hours.
  3. You’ll need to use the tea within the next day or two after making it. You can simply pour a cup of worm tea into your plant’s pots daily for a month. 

Worm tea adds good bacteria to the soil while providing plants with instant nutrients. It’s the perfect option to help your houseplants perk up if they’re starting to show signs of nutrient deficiencies. 

Is Worm Tea Better Than Worm Castings?

Worm tea isn’t necessarily better than using worm castings on potted plants. Both are very beneficial, although they’re best in different situations. Worm tea is good for adding instant nutrients and bacteria to the soil, while worm castings act as a slow-release fertilizer.

You can use both worm castings and the tea on your potted plants to help them get the nutrients they need to grow. However, you’ll need to consider whether your plants will benefit more from a quick or slow-release option.

Overall, worm tea and worm castings are great tools for gardeners. Your plants will experience increased growth and have greener, healthier leaves in no time. You shouldn’t ever have to choose one over the other.

Benefits of Using Worm Castings in Potted Plants

Worm castings are great for your potted plants for several reasons. 

  • They act as a slow-release fertilizer, which you can apply to your houseplants during periods of growth. 
  • The castings offer plenty of nutrients, including potassium, phosphorus, and nitrogen, which all plants need to grow. They also add plenty of protein, iron, and calcium to the soil.
  • Worm castings add beneficial bacteria to the soil that break down organic materials, allowing the plants to absorb the nutrients better. Essentially, they come with everything your plant needs to grow and thrive in its pot. If you’ve never tried them, you will notice a difference in your potted plant’s health soon after.
  • Using worm castings can help keep your plants healthy and can replace using chemical fertilizer. 

For these reasons, many people who keep natural gardens like using worm castings as an alternative to store-bought fertilizers.

However, it’s important to remember that overdoing worm casting and other fertilizing tactics lead to rapid unwelcome growth.

Can You Overdo Worm Castings?

You can’t really overdo worm castings as you can store-bought fertilizers. They won’t cause fertilizer burn or overfeeding symptoms in plants. If you’ve had bad experiences with fertilizers, you’re sure to appreciate using worm castings instead.

It’s difficult to overdo worm castings because they’re slow-release. Generally, the castings take two months to completely release all their nutrients into the soil. Still, it’s good to space out your applications so your plants have enough time to use the nutrients you’ve given them.

They’re 100% natural, so you shouldn’t worry much about using them.

That said, while we are on the subject of taking care of our potted plants, I suggest you check out my article on planting pots on composite decking. It’ll open your eyes to a whole new way of organizing and managing your potted plants: Can You Plant Pots on Composite Decking?


In short, there are many ways that you can use worm castings in your potted plants. You’ll first need to collect them, and using a vermicomposting bin is the most efficient method. Although, you can always gather them from the soil on your property if you want to.

From there, you can use the worm castings as a reliable fertilizer for your potted plants. Since your houseplants don’t have access to nutrients outside their pots, offering them worm castings can help provide them with all the vitamins and minerals they need to thrive.

Alexander Picot

Alexander Picot is the principal creator of, a website dedicated to gardening tips. Inspired by his mother’s love of gardening, Alex has a passion for taking care of plants and turning backyards into feel-good places and loves to share his experience with the rest of the world.

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