Okay – now for the fun stuff. Seed balls (sometimes called seed bombs), are simple balls of clay and soil that contain seeds. They can be placed or tossed into their growing spot, and the clay/soil mix provides the seeds within just enough medium to get started. In most cases this will be more successful than simply throwing or dropping raw seeds. Some mischief-minded people might choose to throw seed balls into vacant lots, traffic meridians, or other under-used urban areas. We would never condone such behaviour, of course. But here’s how to make them!
Step one: The Materials
Seed ball production requires three dry ingredients: Potting soil or sifted compost, potter’s clay, and seeds. The soil does not need to be particularly fertile, and bagged potting soil from the garden centre will do fine. Look for potter’s clay that comes in a powdered form. Red clay works well for this, and can be purchased from most art supply stores. Avoid clay that is advertised as polymer clay, “self-hardening,” or “oven bake.” You want the real deal, proper clay for pottery. The seeds you choose should suit your purpose. Native wildflowers or a pollinator blend might work well. Or perhaps a sunflower seed in each ball. Maybe drought tolerant wildflowers for xeriscaping would make a good choice. You must follow your heart.
Step two: The Ratio
We recommend a mix of two parts potting soil to five parts clay. Once these have been thoroughly combined, add one part water. Additional water may be needed to get a supple mix, but the goal here is for the seed balls to dry out before the seeds germinate. Err on the dry side, if possible. For wildflower seed balls, it might be helpful to mix the seeds into the dry ingredients before adding the water so the distribution is even. For sunflower seed balls, make the mix first, and then add one to two seeds per ball.
Step three: Shaping and Drying
If the seed balls are too large, it may be difficult for the centres to dry quickly. We recommend making them about the diameter of a quarter — about 2.5cm (1″) wide. Form them into balls by rubbing between your palms in a circular motion. If the mix feels crumbly, add a touch more water. It should have the consistency of plasticine. Once formed, lay the balls out in a single layer on a hard surface or over parchment paper. Keep these in a cool, airy place until they turn from dark to light brown. Using a table fan will speed this process along. Once they are completely dry, store them in a cardboard box like a shoe box, and not in a plastic bag. Any remaining moisture should be encouraged to dissipate.
For demonstration purposes only, we felt creating a batch of wildflower seed balls was in order. We’ll be handing these out for free at our retail store on Earth Day, April 22nd. While supplies last only.
We encourage you to Commit to Grow for Earth Day, and create some seed balls. It’s a great classroom project, and fun for all ages. And what will come of it? Only time will tell!
Download our How to Make Seed Balls pdf.