What are the best fertilization inputs for seedlings, growing, blooming and fruiting stages?
When seedlings first emerge, they acquire their energy from the cotyledons (first two leaves or “seed leaves”. ONce they have used all of that initial energy the cotyledons yellow and fall off.
The next stage of development is plant growth which requires a diluted (half strength) amount of nitrogen (N) at every other watering. I personally like to add a small amount of phosphorus (P) and mycorrhizae once every 4 waterings. This aids in root development which will be extremely necessary once they are planted out into a heavier soil. Nitrogen can be used until the first blossoms appear.
Once buds begin to develop, a higher phosphorus ratio will help to promote blooming, and a reduced nitrogen will signal the plant to begin working on reproduction instead of growth. (A nice green lush plant with no blossoms or fruit is an indicator of excess nitrogen.)
When blossoms begin to set and small tomatoes begin to grow, it’s time to add potassium and calcium which will help with fruit formation and cell structure. NPK of 3-4-6 or similar ratio, applied every 30 days as a slow release granular fertilizer will keep your garden producing until frost.