How many seeds in a seed ball?

It really does matter.

There are A LOT of well-meaning articles online about making seed balls that encourage people to use way too much seed (measure by the cup?!?  It’s too bad, since much of the wildflower seed goes to waste instead of doing the world some good. The seedlings in such close quarters just choke each other out, and there’s a good liklihood that none will thrive.

The short answer is: 1-4 seeds.

I figure this out by using some statistics. My goal is to have just 1 or two sprout in each seed ball. Any more and they will be over crowded and compete  for resources. I need to know the germination rate of the seeds. Then I look at a chart that I prepared that employs some statistics, detailed here.

Likelihood of Germination of At Least One Seed in a Seed Bomb

Number of Seeds in Bomb Germination Rate of Seed Ball
1 This row contains the germination % as tested, or one seed per bomb 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90
2 0.36 0.51 0.64 0.75 0.84 0.91 0.96 0.99
3 0.49 0.66 0.78 0.88 0.94 0.97 0.99 1.00
4 0.59 0.76 0.87 0.94 0.97 0.99 1.00
5 0.67 0.83 0.92 0.97 0.99 1.00
6 0.74 0.88 0.95 0.98 1.00
7 0.79 0.92 0.97 0.99
8 0.83 0.94 0.98 1.0
9 0.87 0.96 0.99
10 0.89 0.97 0.99

As you can see, the seed ball germination rate climbs quickly as one begins to add seeds, but then slows down as it approaches 100% it gets. The best way is to use seeds with good germination rate: say 80%-95%.

Based on germination rate, here are my recommendation:

60 – 70%  – 4 seeds
70 – 80% – 3 seeds
80 – 90% – 2 seed
> 90%    – 1 seed

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