I am growing and am transplanting my seedlings- vegetable, herb and flowers in equal portions of peat moss and perlite with a bit of vermiculite added. How soon should I fertilize my transplanted seedlings and what is the best type of organic fertilzer.
Perhaps you could start with seaweed or fish extracts? I like to add leaf compost or worm compost to the soil mix once I start transplanting seedlings. Helps hold a little more moisture and gives a more gentle feeding to the small plants.
Fertilize when the first true leaves (not cotyledons) appear. There is no way to determine what organic fertilizer might be best. While indoors, I would shoot for something that has close to a 2:1:2 NPK RATIO, 'ratio' being different than NPK %s. Still, with organic forms of nutrition, you can't know exactly when those nutrients will become available.
low key fertilizers to start, some of the liquid ones like fish can cause mold to grow if you are fertilizing in a green house. I do not fertilize until after I have transplanted into an organic potting soil, as it will have some fertilizer in it. As others have mentioned, don't transplant or feet until the true leaves have shown up