tomato plants: pot size, potting soil, and fertilizer?!?

Slow down, the plants are still too small to be mucking about transplanting. Wait until you see the roots coming out or near the bottom drainage hole. Right now it's too early to be knocking the plants out of the pot to examine the roots. A four inch pot will support a fair size young plant.......so wait until the plant starts filling in before you turn it upside down, support the soil with your hand and gently tap it out of the pot. Examine the root ball, if dense, time to pot up to a larger pot...8 would be maximum, normally you only go 2 inches, but with tomatoes you can go higher.

The seed start mix is good for several weeks before you need to supplement. When you do start, avoid high nitrogen fertilizer, you want to concentrate on roots, not top growth.........you aren't growing turf grass here. Any "tomato" or "flower" fertilizer is fine. As for farm fertilizer: bull blood is nitrogen......if diluted greatly; egg shells take years to break down, forget it; coffee grounds acidify the soil, they are not nutrients (until composted); horse manure........ah here you might have something, but make "tea" from it. Fill a cloth sack about 1/3 full with manure, tie shut, sink into a barrel of water and let it steep for several weeks. Take some of the "tea" dilute greatly and water with it. (I doubt you'll have time for a school project) otherwise manure is best composted with the egg shells and coffee ground to become compost and used as a soil additive.

for growing tomatoes

Don’t Crowd Seedlings.

Provide lots of light.

Put a fan on your seedlings

Preheat the soil in your garden.

Bury them.

Mulch Later.

Remove the Bottom Leaves.

Pinch & Prune for More Tomatoes

Water the Tomato Plants Regularly.