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How to Use Your Worm Castings

Ok so you got your worm castings… now what? It can seem intimidating to apply that valuable black gold to your garden, but after reading this quick post, you’ll be on your way to saying hello to beautiful growth and harvests.

When it comes to applying your worm castings, you have a few options. First of all, though, don’t be scared! You can’t “burn” your plants with worm castings like you could with harmful synthetic fertilizers. The right way to use worm castings is to USE THEM! But let's take a look at how to maximize your resources and put you in the driver’s seat of your growing seasons.

Container And In-Door Plants

When using containers or pots for your plants, it is best to take about a half cup (or small handful) of worm castings and sprinkle them over the surface of your soil surrounding the plant. I like to “scratch” them in so they have better contact with the soil, but this is just an added bonus as they will do just fine sitting on top. Lightly water, done!

For indoor plants, I would just skip the “scratching” as you won’t have harmful rays beating down on the castings, in turn, drying them out. Plus, another bonus, the castings will help repel pests!

For larger containers, just add another small handful! The ideal application is a “thin layer” across the top of the soil.

Raised Beds and Outdoor Gardens

For your raised beds and outdoor gardens, the application mentioned for containers is still great. However, you could definitely benefit from a heftier amount. As a rule of thumb, I suggest putting a cup of worm castings per square foot. I definitely like to scratch them into the soil so they don’t dry out but a good watering after application can do the trick, too!


One of the BEST ways to use worm castings is when transplanting and starting seeds (covered next). When transplanting a seedling to it’s “forever home,” prepare your soil and dig your hole as you normally would. Once the hole is ready for it’s new friend, simply drop in a small handful of worm castings and plop that seedling right on top of them. This will help reduce transplant shock and get those roots moving.

Seed Starting

Seed starting can be frustrating! Sometimes they don’t take, sometimes they die off before they get strong and other times pests chomp them up before they can defend themselves. Worm castings have you covered! When preparing your seed starting mix (we like to sift our material), simply add 10-20% worm castings by volume. The easiest way to do this is to mix 4-5 scoops of seed starting mixture with 1-2 scoops of worm castings.

Give the mixture a good watering to get those worm castings moving and your seedling’s new roots will thank you for it in no time. Remember, worm castings can TRIPLE the speed of seed germination! That means stronger plants, faster.

One Last Thing

If you don’t have much time to measure and count cups, remember, the best way to use castings is to… use them. I am certainly a fan of sprinkling the castings over my plants and letting nature take hold of them when I don’t have a lot of time.

Another fun and effective way to use the castings is to make a “tea” or “extract!” More on that in another article, though.

I hope you feel encouraged, empowered and ready to boost your plant growth! Let us know what you think or if you have any other recommendations to share, we’d love to hear from you! Otherwise, take a moment to check out our other posts like, How to Create a Worm Farm with Kids.


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