Tag Archives: Great Seed Bomb

How Seed Balls are Made

See how seed balls were made for the 2nd annual Great Seed Bomb event.

The fall season is a great time to plant, including putting out seed balls!  Make some seed balls to propagate more native plants for your garden or restoration project.

Seed Ball Basic Recipe
1 part clay*
1 part finely screened compost or potting soil mix labeled for "seed starting"
1 part water

Mix all together in a small test batch and adjust proportion of ingredients as needed until the mix is the consistency of cookie dough.  Pinch off a bit of the mix and roll into balls about the size of a nickel.  Make a depression in ball, add seeds and then press / roll back closed so seeds are on the inside.  Place on an old cookie sheet or cardboard for 1-2 days until seed balls harden.  Disperse seed balls into your restoration project or garden and let Mother Nature get to work.  Store any unused seed balls in a ventilated (e.g., paper, not plastic) bag until ready to use.

*Optional Sources of Clay for Seed Balls
It seems there are many different opinions and formulas on the source of the clay component of making seed balls, so there are several options:

  • local clay soil (but beware it may already have undesired seeds in it, but it might also have soil micro organisms that are beneficial to plants; best to use local clay soil only if seed balls will be redistributed within same local site where clay was collected)
  • refined clay powder (from an artist's or pottery supply store or online, e.g., The Great Seed Bomb obtains clay powder from Trinityceramic.com, using the "Ranger Red Clay" product)
  • recycled / leftover clay from schools' art class projects
  • new, unused, unscented clay kitty litter

Seed ballsHow Many Seeds to Put in Seed Ball
The answer depends on how scientific you want to get.  If you want to keep it simple, then just add a small pinch of seeds, say 5-10, per seed ball.  If you want to do some additional studying, look up information of the type of native seeds you are using for that batch of seed balls:

  • natural germination rate
  • necessity or neutrality for either light or darkness for germination
  • estimated seed life span

If seeds have a low germination rate in nature and or a short life span, then put in more seeds.  If seeds have a high germination rate in nature and or long life span, add less seeds as you don't want too many tiny seedlings competing for the same nutrients and moisture in one little seed ball, and then competing for sunlight if growing literally on top of each other once the plants get a bit bigger.  If seeds require darkness for germination, put the seeds deeper in the center of the seed ball.  If seeds require light for germination, then put seeds just under the outer surface of the seed ball.  General rule:  the diameter of the seed is about the depth to place it under the outer seed ball surface if it needs light for germination.