How To Make Worm Casting Tea

Worm casting tea is one of the best natural liquid fertilizers for plants and it’s easy and inexpensive to make at home.

Worm tea is packed with nutrients that help plants to grow faster, while also improving the soil quality and reducing pests and diseases.

In this article I’ll show you step by step how to make your own worm tea fertilizer.

This post contains affiliate links. Please read the disclosure for more info.

worm castings

What is worm casting tea?

Worm tea is made from soaking worm manure, also known as castings, in water.

Worm castings contain a wide variety of nutrients and beneficial microbes that enrich the soil and help plants to grow faster and stronger.

You can sprinkle worm castings on top of the soil to fertilize your plants but soaking the worm castings in water produces a rich, bioavailable liquid fertilizer that is rapidly absorbed by plants.

You can also spray worm tea onto the leaves of your plants, which is known as foliar feeding.

Worm casting tea vs leachate

Worm tea is sometimes confused with leachate, which is the liquid that collects at the bottom of the worm farm. 

Worm leachate can contain harmful bacteria and pathogens, so it’s not recommended for use in the garden.

Benefits of worm tea for plants

  • Boosts plant health and stimulates growth
  • Contains essential nutrients including calcium, magnesium, phosphorus, potassium, copper, iron, zinc, cobalt, borax, manganese and nitrogen
  • The nutrients are easily available to the plant and absorbed quickly
  • Discourages fungal diseases and pests
  • Enriches the soil with microbes and beneficial bacteria
  • Helps the soil to retain moisture for longer
  • Improves the soil structure
worm farm

How to make worm casting fertilizer

Things you’ll need:

A compost tea bag (you can use cheese cloth, panty hose, an old sock or t-shirt)

A bucket of unchlorinated water (rainwater, tank water or filtered water)

Worm castings (should fill about one tenth of the bucket)


Fill the bag with worm castings and tie the end closed.

Submerge the bag of castings in the bucket of water and leave it to brew for 24 hours.

The water should be light brown in color after the castings have soaked for 24 hours.

Remove the castings from the water and pour the liquid into a watering can or spray bottle to use on your plants.

How to supercharge your worm tea fertilizer

Beneficial bacteria need oxygen to live and multiply, so the more oxygen in the water, the more good bacteria your worm tea will contain.

If you have a fish tank aerator, you can add it to the bucket while the castings steep to add extra oxygen to your worm tea.

If you don’t have access to an aerating device you can stir the water regularly while it’s brewing to help increase the oxygen level.

Another way to increase the numbers of good bacteria in your worm tea is by adding a tablespoon of molasses to the water while it’s brewing.

The bacteria feed on the molasses and multiply quicker.

worm tea fertilizer spray

How to fertilize plants with worm tea

Fill a watering can with half worm tea and half water to fertilize your plants.

You can use the mixture to fertilize all types of plants including indoor plants, flower plants, fruit and vegetable plants, lawns, trees and even seedlings.

It’s also a good idea to spray the leaves of your plants with worm tea using a spray bottle.

Coating the leaves with worm tea increases the number of beneficial microbes on the leaves and helps to reduce fungal diseases.

Worm tea fertilizer should be used as soon as possible while the beneficial bacteria is still active.

If the worm tea starts to smell bad, it’s time to discard it and start a new batch.

Purchasing worm castings

If you don’t have a worm farm at home you can purchase worm castings online to make your fertilizer.

The castings are odor free and made by night crawler worms that are fed rich organic materials to create highly nutritious castings.

Common questions

How often can I fertilize my plants with worm casting tea?

You can apply worm tea to your plants every two to three weeks while they’re actively growing.

Does worm tea need to be diluted?

I recommend diluting worm compost tea to half strength with unchlorinated water.

If you’d like to use the worm tea every week on your plants you can dilute it to one quarter strength.

What is the pH level of worm casting tea?

The pH of worm casting tea is 7.0, which is neutral.

Is it safe to eat vegetables after foliar feeding with worm tea?

It’s best to wait a few days before harvesting leafy vegetables that have been sprayed with worm tea and always wash the leaves thoroughly before eating.

Can worm tea be used for hydroponic gardens?

Yes, you can add worm tea to hydroponic systems along with kelp and other organic fertilizers for a balanced level of nutrients. [1]

So there are my tips for making nutritious worm casting tea to fertilize your plants.

Worm tea is a non toxic, organic alternative to chemical fertilizers that will greatly improve the health of your plants.


Have you tried vermicomposting or making your own worm compost fertilizer at home? Let me know in the comments below.

Are you on Pinterest? I have boards dedicated to Vegetable Gardening and Garden Ideas that you may enjoy. You can also find me on Facebook.

worm tea fertilizer

Kelly Martin

Hi, I'm Kelly Martin. I'm passionate about gardening and horticulture and I love growing just about everything including herbs, vegetables, flowers, succulents and indoor plants. I've been gardening most of my life and I created this blog to inspire beginner gardeners to create their own urban garden. Read more

Leave a Reply