In the stronger solutions (note that I included 100% as well) they germinated faster and more germinated but they didn't grow as fast as the few that germinated in the weaker solutions, plain water, and media (all were unstratified). But I didn't plant any of them afterwards to see if that effect was temporary. I also left them in the solution for the duration of the experiment and didn't remove them as they germinated. That's why although germination was higher and faster in the stronger solutions, I'd still suggest 1:9 as a compromise. That's also the ratio I've seen suggested most often by people who routinely germinate in H2O2, so one might assume if it caused problems they wouldn't keep doing it that way.
As you can see from the above, soaking in plain water was actually worse than planting straight into media.
