(VIDEO) Soil Blocks, Now with More Cowbell.
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We have already talked about our love of soil blocks as an alternative to traditional seed-growing containers. But no we have taken it to the next level. Come learn all about soil blocks and how they can entertain while also helping you grow an abundance of food.
Watch “Four Inch Soil Blocks” on YouTube >
What is a soil block?
Imagine a block… made of soil. That’s all a soil block is, a cube of compressed soil used for starting seeds. They are made using tools called soil blockers which come in a range of sizes from as small as 3/4 of an inch to as large as 4 inches. The soil blockers are designed so that the blocks made by smaller blockers fit neatly inside the blocks made by larger ones. The tool itself consists of a spring-loaded handle attached to a set of forms. There are a couple of knock-off brands, but the original tools come from Landbrooke Soil Blockers in England. We’ve learned through experience that it’s best to invest in quality tools, so we only use this brand. With good care they should last for our gardening lifetime!
How do you use soil blocks?
We use soil blocks to give our vegetable seeds a head start indoors before transplanting them to the garden outside. The tiniest blocks - 3/4” - which look like brownie bites, are perfect for germinating seeds. Once the seeds have sprouted, we put those blocks inside the 2” blocks. This gives them space to grow their roots and develop a few sets of true leaves. At this point some plants are ready to go out into the garden while others need more time and development in a protected environment.
Before adding the 4” soil blocker to our homestead, we would “pot up” these bigger seedlings to plastic pots. But as we talked about in our post, Going Potless, we have started moving away from containers for a variety of reasons. The 4” tool is a little spendy, but we decided to make the investment this spring. So now when plants in 2” blocks need a little more space and time inside, we put them (now two-in-one) into 4” blocks. When the plant and weather conditions are right, these too get transplanted into the garden.
How do you make soil blocks?
As Kevin says, if you enjoyed making mud pies as a kid, you will be great at making soil blocks. In the simplest terms, you stuff soil into the metal form and push it out in block form. As with everything though, there is a learning curve to it. There are two key things to keep in mind: the mix of your soil and the method of using the tool.
Soil mix - Getting your soil mix and consistency right is very important to creating blocks that keep their shape. You can buy seed-starting mix at most garden stores or you can make your own. There are many recipes out there. We’ve developed our own recipe for soil or growing medium that’s great for raised beds, containers, and starting seeds. We use this recipe, but sift it for creating seed blocks. The variation in sizes of material is great for beds, but cause the blocks to fall apart. To this refined soil we add lots of water. The mix should resemble brownie batter but be just a touch drier. If the mix is too dry though, your block will crumble when you squeeze it out of the form. Getting the right mix is more of an art than a science, so you can expect to have a few blocks crumble before you zero in on the best formula.
Tool Technique - Of all the soil blockers, using the 4” is the trickiest. Where the other soil blockers make multiple blocks at once, in perfect cubes, the 4” tool is different. It makes one block at a time and each block has a 2”-cubed void in the center on the top of the block. The thin soil edges around this void crumble easily if you don’t have just the right soil mix. Fortunately, if you find yourself getting frustrated and making imperfect blocks, you can always take a break, rinse off the blocker, and tap on the side of it with a metal spoon to enjoy the soothing sound of a cowbell.
Once you’ve relaxed a bit, reassess your soil mix and try again. The best technique we have found is to first use a trowel to fill in the space around the 2” knock-out that creates the void in the block. Once that is nicely filled, you can push the blocker straight down into a mound of your soil/water mix. You have to apply a decent amount of pressure and you may need to use your trowel to scoop additional soil under the edge of the blocker as the mound compresses. When the blocker is completely full you will begin to see moisture leaking out of the top of the form. When you pick the full blocker up you should have a convex mound of soil sticking out of the bottom of the form. Use the trowel to scrape off the excess until the bottom is completely flat and flush with the metal edges of the form. You will then set the blocker on your tray (we use plastic seedling trays with damp cardboard in the bottom to retain moisture) and slowly and gently compress the spring-loaded handle. Let the spring go back to resting position without picking up the blocker, then slowly compress once more and gently lift the blocker up to release the finished block.
If all goes well you will have a perfect little block of soil that looks kind of like a mini volcano but with sharper edges. If all does not go well… rinse off that blocker and start tapping away with that spoon. You probably need more cowbell.
Are soil blocks worth it?
After nearly two decades of gardening and trying many different seed and plant pots, we feel strongly that soil blocks are the best option for starting seeds indoors. We have observed that the seeds germinate, or sprout, quickly and consistently. This saves us time and seed. Using soil blocks also reduces the consumption of plastic products and the need to store containers in the off season.
Most importantly, the roots don’t get bound up in the pot. This prevents a lot of transplant shock and allows the plant to quickly become established in it’s final home, making for a stronger plant overall. Strong plants tend to produce more food and are more resistant to pests and disease.
While up-front investment in soil blockers is much higher than plastic or compostable pots, in the long run they more than pay for themselves.
That’s a wrap. Or a cow bell. Or a block.
While we love soil blocks and hope you will try them, that doesn’t mean they are right for everyone and every garden. Don’t let perfection paralyze you - start where you are, use what you’ve got, do what you can.
If you like this info then you might also enjoy our FREE Quick Start Vegetable Gardening Guide >
