DIY Raised Bed Garden Soil

By Mikael Maynard

As the cooler months creep upon us, our winter seedlings are beginning to outgrow their starter trays in the green house, indicating their readiness to be planted in the great outdoors! About one third of our seedlings at Johnny Appleseed Organic Village will be planted in the raised bed garden.

After harvesting the summer annuals that were previously growing in the container garden, our farmhand, Niki Pramik, prepared a fresh batch of raised bed soil to top off, enliven and mix in with the existing soil. She did this all by hand and from scratch! She explains that “it was an easy task, but time consuming.”

The DIY soil mix that Niki used includes: worm castings, pine bark, sharp sand, coconut coir and rice hulls. Each ingredient adds a unique and helpful component to a raised bed growing system, and you can feel good about growing your food in the mix, since they are all safe and environmentally conscious mediums.

According to our farm manager, Joshua Andersen, ”Worm castings are a source of nutrition as well as a bacterial inoculant, pine bark promotes air flow, sharp sand promotes beneficial drainage, coconut coir helps with water retention and rice hulls also help with drainage. In a raised bed situation, drainage is super important, otherwise your plants’ roots will rot.”

Interestingly, the process Niki used to make the raised bed soil did not include a specific recipe! After a few seasons of experience, she says she can ‘feel’ when the batch is ready.

For those of you who don’t have “a few seasons of experience,” here are some easy-to-follow tips. Each batch of soil needs three things: 1) a nutrition component, 2) a water holding component, and 3) a drainage component. Depending on what mediums you choose, you may need a little more or a little less of one or the other, but all around you are shooting for about one third of each.

The consistency of a good raised bed soil mix has a lot to do with how it interacts with water. When making your own mix, take a sample and pour a little water over it. Then, pick it up and see how it feels. You want the mix to retain moisture for root uptake but you don’t want it to become so saturated that the roots rot! Next, pour a lot of water over the sample and see how it feels. If there is an excess of rain from a heavy rainfall, you want to make sure that that water is going to go down and out the bottom quickly.

You don’t need to limit yourself to exactly the materials we used. See what growing mediums you can source in your area! Maybe you don’t have worm castings, but you have compost. Great! Maybe you only have pine bark and not rice hulls. No worries! 

Using the resources in your community and mixing them with your senses as your guide is a great way to get in touch with the soil and the needs of the plants themselves. Freeing yourself from the idea that you need a recipe opens up the door to many sustainable growing mediums — including some we may not have thought about previously!

Niki recommends mixing all of the ingredients together by hand, or if you are working with a bigger space, a small cement mixer. When using a cement mixer, you will often want to stop the mixer and reach in to feel and observe the soil, because without a recipe, your senses (as you know) play an important role in knowing when it is ready! With that being said, always observe strict safety guidelines when operating a mixer to avoid serious injury.

Our raised bed container garden consists of corrugated metal beds on a cement slab, and our mix is custom-tailored to perform in this environment. Depending on your growing situation, the process and materials we use to make raised bed soil may be different than the process that would most efficiently suit your needs — so feel free to use your intuition.

And, once you give it a try, let us know how you got creative with your mix!