Noralesong
Chirping
Of course! So when I made my seedling mix, I used potting soil, coco coir, blood meal, worm castings, vermiculite, and perlite. For me, the fertilizer is already worked into the soil and so I've not needed to feed mine at all.Can you explain the application of worm castings and blood meal? Do you sprinkle it on, dry? Do you add it to water?
Now for you, if you don't have plans to pot up currently, you can sprinkle it along the top and then top water. It's not a big deal to top water, especially since you're using pots. If you were using soil blocks (which is what I do) it would be a lot more difficult to do this without a repot. I would give a reasonable dusting, since there's no need to worry about it burning the plant and it'll just feed over time.
Given that your plants are in a tray, top watering will help saturate and distribute the nutrients and then the tray will capture the rest of the water and allow for it to be absorbed over time through the holes in the bottom of your pots.
You could also do the same thing in the garden. If you ever notice your tomatoes do this, scatter the blood meal and worm castings around the stem and water. If you have blossom end rot, you'll need more calcium, which you can use bone meal for.
I have a preference for organic fertilizers, although I do apply water soluble/mixable fertilizer over the entire garden during peak season (I use SuperThrive which is also organic). I can't speak to non-organic, but I'm certain there are others than can. This has just worked well for me, so no reason to change it if it's not broke.
Also a little goes a long way. A bag of blood meal and bone meal seems small, but it's a VERY fine dust. Be careful not to breathe it in because it stinks lol. Most organic fertilizer is smelly, which I suppose is the biggest downside.