Happy Saturday! The weather here in northern Iowa has been off the charts. Yesterday was in the low seventies and its supposed to be in the high sixties most of this week. It’s hard to believe we’re still in the middle of February! But we know its only short-lived, so we’re making the most of the sunshine.
We’ve started putting in raised garden boxes, where a lot of our cold weather crops will be grown, with a transition into beans, and I wanted to quickly share the gardening technique we’re experimenting with this year. It’s called the Core Method, and its been around for some time. But this is the first year we’ve used it in our own garden.
The method is simple. The idea is to incorporate organic material down the core, or center, of your raised bed before planting. As this material breaks down it will release vital nutrients to your plants while enriching the soil. Most of the time this is done with rotted straw, but we’re using rotted grass clippings and mulched leaves.
We have this great space in front of the old brick barn, nestled on the southern side of the hog shed, where the ground is relatively flat. This picture was taken yesterday late afternoon, but we get at least 8 hours of direct sunlight here, and the hog shed provides decent wind break. Our plan is to put in nine raised beds this year, and to incorporate some flowers throughout the space to attract those necessary pollinators.
Once the box is built and placed, I’m laying cardboard on the bottom, right over the grass. This allows me to not have to dig the grass up (its warm but the ground is still frozen 4 inches below the topsoil) or lay down plastic. I want my plants to have access to the rich soil below and for their roots to not be restricted to the depth of the box (16 inches). The cardboard will kill the grass and act as a weed barrier as it breaks down over time.
After the cardboard is placed and soaked really good, I’m putting down a thin layer of mulched leaves from our fall pile. Then I’m placing the rotted grass clippings right down the middle of the bed in clumps about six inches deep. The grass is rotting but still green, so it should be a nice source of nitrogen for my spring crop.
Many people use straw instead of grass clippings. I don’t have access to straw without going out and buying it, so I’m using what I have readily available. The important thing to remember is that whether you use straw or grass, it should be partially rotted already. Don’t use it if its wet and slimy, as this will work against the balance you’re trying to create in the soil (think composting; same principle), and could contribute to plant disease or hinder growth. You don’t want to use fresh straw either, as you might not see the benefit of it breaking down until the following year. Using material that is already in the process of breaking down will give your plants a continued source of nutrients throughout the season. Just make sure you don’t use material that has been sprayed with a herbicide, or grass that has gone to seed! (I wouldn’t use hay either, as most hay has seed in it and will create unnecessary weeding.)
After the grass clippings are placed, I’m adding native soil from the property. Our soil here is a rich blend of sandy clay and I want to use it as much as possible. We had a new septic tank put in last summer, and after the leech field was excavated we ended up with a large pile of black earth. This is what I’m using to fill our boxes.
I’m starting at the sides and spreading the native soil throughout the box. I’ll cover the grass and mulched leaves and then follow with a layer of compost, which we’re having trucked in from a local business within the week. Once I add compost, I’ll mix in more native soil. Then I’ll be ready to plant.
We hope to sow cold weather crops like kale and radish over the next couple weeks. I’ll put up plastic hoops over the boxes to keep the soil warm and to protect the plants from late winter flucuations in weather. Any snow we get will hopefully serve to insulate the boxes as well. At least that’s the idea!
By the way, you don’t need to have raised beds to incorporate the Core Gardening Method. If you already have or are establishing raised beds on the ground, whether permanent or annual, you can use this method to enrich your soil. This is a neat and organic way to let nature do the work for you, and works well on a no-till garden plot!