A Step-by-Step Guide to Making Your Own Soil Cubes From Scratch
While store-bought discs are great for allowing your seeds to get a jump-start in growth before transplanting, creating your own growing medium adds something to the gardening experience that you just can’t buy.
“The glory of gardening: hands in the dirt, head in the sun, heart with nature. To nurture a garden is to feed not just on the body, but the soul.”
For many gardeners, those poetic words of Alfred Austin ring so true. The glory of gardening reaches far beyond aesthetic results to touch us in ways that are as much spiritual as they are physical in nature. Gardening is a connecting rod between nature and us. And, for those who enjoy a more hands-on approach to gardening, this hands-in method of creating your own soil cubes is satisfying on many levels.
Essentially, soil cubes are what their name implies—cubes made of tightly compact soil. Soil cubes are for starting seedlings in a controlled environment before they are planted permanently. There are many starter kits available on the market today. You may know them as peat pods, peat pellets or even seed pellets. While these store-bought discs are great for allowing your seeds to get a jump-start in growth before transplanting, creating your own growing medium adds something to the gardening experience that you just can’t buy.
A good germinating medium must be fine and uniform, yet well-aerated, loose and free of pests, diseases and weed seeds. So, while purchasing peat pods is certainly an option, making your own can be a rewarding experience. Not only do home-made soil cubes work just as well, they reduce your carbon footprint and impact on the environment by avoiding paper packaging waste and the plastics involved in wrapping. Not to mention, you receive the joy of knowing “I made those myself.” Here is a list of the items you will need to get started. The screen is optional.
You will need:
- Sterile seed-starting mix intended for soil blocking. An equal blend (50/50 each) of peat moss and vermiculite/perlite will work also. Just be sure it’s sterile.
- A large bucket, tub or mixing pan with a wide bottom
- A flat (to put the mixture in)
- A screen (some gardeners like to use a quarter-inch screen to sift out the big chunks)
- A knife
You can buy a mechanical soil blocker for about $30 that forms the cubes in a mold, but you can also just spread the mixture out in a flat and cut it into 3-in. squares with a knife. So, without further ado, let’s get started creating these earthy, fun little cubes.
Step 1. Dump the peat mixture into your mixing pan. Wet it down and mix it up using a hand rake or whatever you have handy until the mixture reaches a consistency that resembles thick porridge. You may need to add some clay-like garden soil to help it reach a consistency that will hold its shape. Be aware, however, that backyard clay soil is not the best to use. In fact, it may be the worst. This type of unpasteurized soil can contain weed seeds, diseases and fungi that can kill young plants. The process is not an exact science, so wet and mix until it feels about right. Realize that it may take up to 30 minutes for the peat moss to become fully saturated, so let it soak for a while.
Step 2. If you purchased a mechanical cube former, it came with instructions. Follow them. If you plan to cut your own, fill a seedling flat with the wet potting mixture. Press the mixture firmly into the flat using the palms of your hands. This pushes out the excess water and forms the mud cake from which you will cut your blocks.
Step 3. When the right consistency is reached, cut your homemade potting soil cake into 3-in. squares. With a pencil or an object of similar diameter, make an indentation in the top of each cube for seed placement. Allow the blocks to dry. This usually takes two to three hours on a warm sunny day.
Step 4. When ready, place a seed or two into each cube and moisten gently. A mist setting on your garden hose attachment works best. Any more pressure and you run the risk of damaging the cubes and shocking the seedling.
Once the seedlings grow to the desired height, you simply dig a small hole wherever you are planting, drop the nutrient-rich cube in and cover the top of it with dirt. The beauty of homemade soil cubes is how effective they are in reducing transplant shock. I like them because they also eliminate that tough netting on the popular discs that you buy, which isn’t always so biodegradable.
One final item of business I’d like to touch on is sterility. Before you begin any gardening project, it is important you wash all your flats, pots and trays as well as any gardening tools you plan to use. To eliminate contamination, after washing, rinse them well with a solution of one part chlorine bleach to 10 parts water using a spray bottle. This will ensure all micro-organisms and plant diseases are eradicated.
That’s it! Soil cubes: nature’s way of showing gardeners everywhere that it’s okay to be a little square.