The results from my soil experiment are in. It’s a real head-scratcher.
(seed starting mix left, potting soil right)
Kale: The Kale in both seed mix and potting soil germinated the same day, and grew at the same rate for a week. After two weeks of growth, the seed mix kale is far outpacing the potting soil. Winner: Seed starter mix
Spinach: None of the seed mix spinach germinated at all. Four out of 6 seeds germinated in potting soil. Winner: Potting soil
Lemon Balm: No lemon balm germinated in either soil mix at all. I think this is because I failed to score the seed coat properly, but I’m not really sure. Winner: no one
Final Score: Potting soil – 1, Seed starter – 1
So there’s no definite winner here, and I don’t feel like I really know why I got the results I did. I thought I did a great job making conditions the same for both cell packs of seeds, but maybe it wasn’t equal. Maybe some seeds do better in seed starter mix, and others do better in potting soil. I’m going to think about this a bit and retry my experiment again soon. If you have any ideas/input about how I should go about my next trial, please let me know in the comments section.
Update: Please also check out my previous post on the topic Seed starting mix vs. potting soil as well as my more recent post More thoughts on potting soil vs seed starting soil.