I planted my seeds about a week ago (after soaking in a weak bleach solutuon, performing the float test, and stratifying for 6 weeks), and in the past few days I’ve noticed some greenish-white mold that looks like cotton candy growing around a few of the seeds. Is this just helping the seed coat to break down, or should I try spraying them with a hydrogen peroxide solution to stop it? If I need to get rid of it, what percentage of peroxide should be in the solution? I tried growing other perennials from seed for the first time last spring and ended up losing alot of them to damping off, so now I’m totally paranoid about having everything sterile.
There are many opinions here on this Kate, but in my experience this green fuzzy stuff is not the type of mold that helps seeds germinate. It also tends to be resistant to hydrogen peroxide soaks as well, but you can give it a try. Clean off the seeds and soak them in straight bottled 3% hydrogen peroxide for 24 hours. Then put them back in fresh media (whatever you’re using - paper towel/soil/coir, etc). If mold starts to regrow after a few days (my guess is it will) you can try spraying the seeds with Safer Fungicide which is sulfur based. That seems to slow down the growth of the mold considerably and my seeds have germinated fine after spraying.
Many here have had good experience using coir as a mold inhibitor as well.
In the future, a 24 hour soak in straight 3% hydrogen peroxide rather than diluted when preparing the seeds initially may help too.