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Pasteurize Worm Castings

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How To Pasteurize Worm Castings

We keep a worm bin in my seedling room in the basement and my plants and gardens are extremely grateful for it!

The leachate (or worm juice!) is added to the rain barrel, or diluted and sprayed on tomato plant leaves to help stop disease if we get a heavy rain.  And the castings are added to our seedlings or straight to the garden to give the plants a boost!

But there is one thing that I absolutely hate about it…

The random seedlings that sprout up and confuse the heck out of me!  When I add castings to my seed starting mix and decide to start my tomato plants it can end up being quite the guessing game!

Pin Me For Later!!When random seeds sprouts from your worm castings it can be extremely frustrating! Especially if you use them for seed starting!  Learn how to pasteurize worm castings to get rid of the rogue seedlings!

So when I stumbled across the article, Pasteurize Your Own Compost, on I was beyond excited!

Apparently, by pasteurizing compost or worm castings, you will kill the rogue seeds.  Not only that, but you also kill bad organisms while allowing the good to survive!

So how do we do it?

The process is extremely simple.

First, I separated the worms from the castings.

After that, I lined a baking sheet with parchment paper.  (Note for next time, I will use aluminum so that the moisture doesn’t soak through.)

Preheat the oven to 200°F.

Add the castings to the pan and smooth out to about 3-4 inches thick.

Insert a meat thermometer and put the pan in the oven.

Keep an eye on the thermometer, and once the internal temp reaches 160°F set your timer for 30 minutes.

After 30 minutes remove it from the oven and allow it to cool completely.

There you go, that’s it!  You’re all set to add it to your garden or seed starting mix!

I was really worried that this would dry it out completely, but you can see in the picture above that it is still moist.


Have you pasteurized compost?  What was your luck? Tell us in the comments!


Marianne Byrd

Monday 4th of September 2017

I need info re. raising mealy worms.

Vanessa Lund

Thursday 16th of February 2017

This is great tip. I actually purchased worm casting organic soil and I love how much my veggies have grown.

Skip The Bag

Sunday 5th of February 2017

I hadn't thought to do this, but it makes sense! Thanks for sharing on the Waste Less Wednesday Blog Hop!