How to store and use worm castings

Estimated reading time: 11 minutes

Are you looking for tips on harvesting, using, and storing your worm castings? Many people start vermicomposting to produce nutrient-rich compost for their house plants and garden. Then, after months of adding food and bedding- it’s time to collect the compost. 

Worm castings, also known as vermicompost, are a nutrient-rich fertilizer that is produced by worms. They are highly valued by gardeners and farmers for their ability to improve soil health and plant growth. However, it’s important to store worm castings properly to ensure they retain their potency and effectiveness.

Let’s not waste time and dive in!

Benefits of worm castings

Worm castings are a natural and eco-friendly alternative to chemical fertilizers that offer a multitude of benefits. By feeding your worms the right kind of food, you can boost the nutritional value and environmental impact of your castings, making them an excellent choice for promoting healthy growth in your plants.

Worm manure is a rich source of beneficial bacteria and microbes that can significantly improve the health of your soil. Additionally, it contains essential nutrients like potassium, calcium, phosphorus, and nitrogen that are crucial for promoting healthy plant growth. Incorporating worm manure into your gardening routine can lead to bountiful harvests and flourishing plants.

In addition to these crucial nutrients, worm casting helps the soil retain moisture. 

Healthy soil has a vibrant mix of microbes, bacteria, fungi, and nutrients. 

Chemical fertilizers often only add nitrogen, phosphate, and potash. 

These chemicals cannot add other types of significant biodiversity, such as bacteria and microbes. Instead, worm fertilizer reintroduces those items back into the ground in an all-natural way.

Some interesting research from Ohio State found that worm castings can aid in all stages of plant growth. Everything from helping seeds germinate more consistently to how much the plants eventually produce. They even gave the plants some natural immunity from common diseases and pests.

How to harvest worm castings

Over time, you will run out of space in your worm bin. To make more room for your worms, you’ll need to remove all nutrient-rich compost, also known as worm poop.

We suggest reducing the amount you feed your worms as you reach the top of the bin. Leaving your container uncovered allows your worms to break down any excess food before harvesting. Then, when your bin no longer has any visible paper or food scraps, you’re ready to harvest.

The easiest way for beginners to harvest their compost is with light and a little time.

To harvest:

  1. Open your bin, and expose the bin’s contents to natural light or the light from the lamp.
  2. Wait 15 to 30 minutes with the top off; worms are light-sensitive and will burrow away from the light.
  3. Carefully remove the top inch of compost.

Once you’ve entirely removed the top layer, repeat the first step. Wait 15 to 30 minutes and clear away another layer. Eventually, you will get to the bottom. There is no need to remove all of the compost possible. Instead, dig down until the worms can no longer burrow any deeper. Add some food and new bedding, and you’re ready to start composting again.

How to store worm castings

After getting the worm castings out of the bin, you must let them dry. Worms prefer to live in a moist environment. However, if you store the compost in this state, it will mold. How you dry out your castings often depends on how much you have. Letting the castings dry out in an upcycled cat litter tray is easy.

After a few days, sometimes up to a week, much moisture will have evaporated. If the castings are completely dry out, you will lose many beneficial microbes. Once you get it to the correct consistency, it’s time to find a storage container.

Finished pure worm compost
Finished pure worm compost in an upcycled takeout soup container. Note- the tiny air holes in the lid.

As you transfer your worm compost to the storage container, you may want to sift your compost for any cocoons or missed worms. Try your best to get any worms or cocoons out of your castings, as non-native worms can harm your local ecosystem.

Transfer the castings into a container that can retain moisture but still has some airflow. Many use mesh sandbags, old protein containers, or other upcycled bins. Whatever you choose to store your castings in, be sure it has even just a tiny amount of airflow.

Worm castings stored in the right conditions can last up to three years

How to use worm castings

You can see there are so many great benefits to using worm castings. But, of course, how you use your worm castings depends on the application.

  • Add 15%-20% worm castings to a starting potting mix to help new or repotted plants.
  • Till up to 33% worm castings into raised bed gardens.
  • Brew into a worm tea

How to make a basic compost tea

One of the most common ways to increase the benefits of worm castings is to create a compost tea. There are a lot of different methods and strategies for aerated and non-aerated compost tea. Compost tea is a way to increase the yield and beneficial microbes in the fertilizer.

For this recipe, you will need:

  • 1- a five-gallon bucket
  • 5- gallons of rainwater or purified water
  • 1- stocking or pantyhose
  • 1 cup worm castings
  • 1- fish tank air pump
  • 1- aeration stone
  • 2-3 Tbs cups molasses

Start by filling your five-gallon bucket with five gallons of rainwater. If you do not have rainwater, try to fill the bucket with non-tap water. Tap water is often highly chlorinated and kills many beneficial microbes you cultivate. Mix in the molasses.

Next, cut your stockings in two, so each leg is separated. Take one of the pieces of pantyhose, and place your one cup of worm castings inside. Let worm castings settle to the bottom and tie off the stocking. Place it in the bucket. Finally, connect the air stone to the pump and aerate for 12-24 hours.


There you have it, your essential guide to storing and using your worm castings. There are so many different ways to harvest and use worm castings. These are just a few ways to help you get started along your journey. If you have tips or tricks you’ve found beneficial in your worm composting journey, please share them in the comments below.

Thanks for reading, Happy composting!