Yeah, it's tricky, because you have to estimate the stage of your seed's young roots to keep from damaging them by oxidation. 1% peroxide is fine to use as a fungal preventative with growing seedlings, but it won't stop a persistent mold once it's taken hold. 3% is great as an initial soil drench and as an aid to germination, but I would probably not water my little two leaf seedlings with 3% too much (especially if they were already dehydrated). So, imo, 3% peroxide is best before sprouting to prevent damping off and to soak seeds in initially to reduce infections and stimulater germination, but less so as a emergency fungicide. I'd suggest physical removal of as much mold as possible, then water thoroughly with 1% peroxide, and consider if the mold is from over-watering. In my experience, almost all container molds get negated by competing microorganisms if planted in the ground, but that's less true in some richer planter mixes and untrue if you just plant up a bigger container. If you want a more complex answer as to why peroxide aids in seed germination, there's a number of good peer-reviewed papers out there. Here is a link that might be useful: A Mechanism for Promoting the Germination of Zinnia elegans Seeds by Hydrogen Peroxide

Hi catherinet. I 'thought' I remembered you didn't have fish but didn't trust my memory, lol. I dunno, duckweed is certainly not harmful and even beneficial but I do wonder about a thick covering blocking light to your lilies as well. My fish keep my duckweek under control - I have to grow it in a separate container it disappears so fast. I don't recall you ever mentioning why you chose not to have fish. And I may well get slammed for what I'm about to say.(Note here, my fish are my pets, all have names and I am devastated when I lose one.) However....if I were in your situation, I'd consider tossing in a handful of rosy red minnows and let them do your work for you. They have a short life span, stay small and will survive on their own in your healthy plant environment. No supplemental feeding necessary and little chance of getting emotionally attached. There I've said it. As to your little waterfall, if you miss it, start it back up. When it gets covered in algae and starts looking yukky, shut it down for a few minutes & pour H2O2 on it. Let it do it's thing then rinse with the hose jet spray. It'll look like new and won't harm your plants (or fish for that matter).

Thank you aardvark. Did you find this quote from phaghat to be true: "seedlings have to be transplanted very small to avoid a period of slovenly appearance from the shock." I hope not because I have already had to transplant them twice and by the time they get to the garden they will be anything but small. I have some more seeds I could start later if these were done too early??

planted my last load of neem seeds, and a few are showing radicals :) so with any luck i'm sorted. (germ notes..) i received them from india last autumn.. some germed then but didn't survive the winter. had slow germs and issues with fungus gnats in early spring. 24 hour soak, husked them.. i like to germinate in a tupperware with a 1/2" of perlite on the bottom and a 1/4" of water, occasionally dropping some h2o2 if there's a fungus outbreak. they go in soil when they've got a nice radical.