any info about how early you can treat seedlings with neem oil

avoid neem oil for the first few weeks before the plant is somewhat established. Otherwise use a very very light solution. I would suggest dipping them in a very , very light solution. Maybe a 1/4 teaspoon per quart. But if you have a pest problem this early then your in some trouble.

neem oil because you have mites?

If so go get a no pest strip at walmart for 5$ no more mites my friend

You don't soak seeds in neem oil period. If you have fungal gnats then it's not the fault of the plant or the seed. It's your fault for not having a clean grow area (if indoors, outdoors not much you can do) or it’s your fault that you are over watering. (the most common cause of fungal gnats)

To help keep the plants healthy and stronger you can ad some barrier & silica to your feeding schedule to help keep the pests away and the plants healthy.

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Peace
Zandor

If you go cheap you grow cheap. - Me