The term was originally "seed grenade" coined by Liz Christy when she started the "Green Guerrillas" in New York City. The first seed grenades were condoms filled with wildflower seeds, water and fertilizer. This was the start of the guerrilla gardening movement in the early 1970's. Current "seed bombs" typically use clay as a binder to keep the seeds protected from being eaten prior to germination.
For years I have tossed seeds into the lot across from my house in hopes that something wonderful would take root. I've even transplanted a few perennials over there to have at least some bright spot! However, this morning, when I found several packets of old seeds - I thought why not try a few bombs!
The recipe I used did not include clay, as I didn't want to run to the store first. Plus, there are lots of good substitutes for clay, after all it is just a filler. So a creative and frugal approach was born. The clayless seed bomb! I've also made cast paper seed bombs that I use as gift tags and ornaments. Different recipe, but still easy. That blog post is here.
Here is what I came up with for recipe and process using items which you have in your kitchen already:
In a large bowl, mix
- 1 1/2 cups of flour and 8 - 10 TBS corn starch
- Place seeds into flour and mix. Observe distribution of seeds to estimate amount of soil to add 1/2 to 1 cup of water & mix into a smooth paste or dough.
- Gradually add 1/4--cup of vegetable oil
- Knead the dough until it develops a firm consistency.
- Sift about 3 cups of potting soil and add into mix (Easy method, just dump it in, but then you'll need to work it more to get is smooth.)
- Continue to knead to spread seeds and get to desired consistency.
- Pull of pieces and roll into balls or logs – can add more soil as needed.
PS I updated this recipe. In subsequent trials with the seed bombs I used more corn starch and sifted the soil mix to have only the finest grains. This helped make more homogeneous dough. I also add the seeds into the flour first. This way I can see how many there might be in a clump. If I use more than 2-3 packs of seems I will add more dirt, but with only 1 pack of seeds maybe just a dusting.