We have worm castings! Now what? There are two ways to use the castings Vermicompost and Compost Tea.


A quick and easy way to use castings. Sprinkle the vermicompost onto the soil around the base of your plants. This is called topdressing in farm lingo. Vermicompost is richer than regular compost and has different microbes, so it takes only a sprinkle.


The fun and experimental way to use castings is to make compost tea. The microorganisms found in worm compost support plant health. Using compost tea is a bit different than using a fertilizer, it may add some minerals or vitamins from the castings, but mainly it gives a boost to the life of the soil. It’s like probiotics for plants.

Some gardeners like to put compost tea into a spray bottle and spray it directly onto the leaves of plants to boost immunity. This is thought to cover the surface with good bacteria so that there is no place for ‘bad’ bacteria to land. However, only do this with a good quality compost tea (if it smells bad, don’t use it) and spray the bottom of one leaf to test it before spraying the whole plant. Spray on a cloudy, but not rainy day.

These little microscopic organisms need air and food to multiply. Chlorine and chloramine used to treat tap water can kill the bacteria we want to grow. Chlorine evaporates, therefore try filling a bucket and leave it stand overnight and use filtered water.

For large scale production of compost tea, a special bubbler is used and the tea is left to brew for 24 hours. At home, you can make a simplified version. We will show you how with the activity instructions below.






  • 20 litre bucket
  • Large stick for stirring
  • Filtered water
  • 1 cup worm castings
  • ¼ cup Molasses
  • Watering Can (remove the filter so it doesn’t get clogged)



Step 1: Add your ingredients

Add the water, castings and molasses to your bucket and stir vigorously to aerate (make bubbles).

Remember, the organisms need air and food to grow. Stirring will give it air and molasses is the food.

Step 2: Keep Stirring

Step 3: Stir more. Stir fast.

Stir in every direction. It’s so satisfying.

Step 4: Wait, don’t stop yet. Nice bubbles though!

Ideally, stir for an hour or two. It’s ok if you take breaks! This is an ideal activity for a group of small kids to take turns stirring the pot.

Step 5: Pour the tea into a watering can.

Pour tea into watering can and remove the filter so it doesn’t get clogged.

Step 6: Water your plants!

Like any fertilizer, water the soil first so your tea doesn’t run off the top of the soil. I like to prioritize plants that might be struggling to grow like beans.

WARNING: If your compost tea becomes anaerobic, and smells bad, don’t use it on plants. Aerobic means that it has air. Anaerobic means that it does not have air. When it becomes anaerobic, completely different bacteria are present, not necessarily the ones we want to use on our plants.

e challenge you to experiment and observe. Try giving one planter compost tea and leave it off another, then see what happens. You can use our Potato Planting 2 activity as a guide on how to record your findings.


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