A Gardeners Forum Forums General Discussion The Food Garden Forum The Tomato Forum Mixing Fertilizers: a perfect nutrient profile

Hey guys, first post.

I've been trying to put together a tomato fertilizer.

I wrote a program that figures something out for me:
If I have 2 or three different fertilizers with different NPK ratings, I can figure out how to mix them to get my desired NPK rating.

So you take your desired NPK rating and the NPK ratings from your fertilizers and it'll tell you how to mix them to get what you want.

The problem I have is deciding on the best NPK rating for tomatoes. After checking many internet sources, I've come up with the following profile for a tomato fertilizer:

Nitrogen : 12.5%
Phosphorus: 0.9%
Potassium: 12.5%
Calcium: 1.40%
Magnesium: 4.8%
Boron: 0.15%
Mo: 0.012%
Sulphur : ?

Does this seem right to you guys?
Thing is, if it was right then I could expect to find similar formulas on the shelves.
But I don't.

Anyway, the closest match with a mix of the ferts I have available is:

0.3g Miracle Gro
0.38g Phostrogen
0.33g Epsom Salts

per litre of water.

Which gives me:

Nitrogen: 125.2 ppm______perfect
Phosphorus: 43.94 ppm____too high
Potassium: 125 ppm_______perfect
Calcium: 14.3 ppm________too low
Magnesium: 47 ppm________perfect
Boron: 0.32 ppm__________too low
Sulphur: 30+sulphur in Epsom Salts(?)


So: would you say the profile was correct, completely wrong, excessive, poor, what?

Any advice would be appreciated.

For me if I read your list right the phosphorous is way low for me. I want it as high or higher than the N or K. Especially early in the season. I use mainly manure now with a foliar spray but never want then N high as you will get growth but no production. Just my experience. JD

The best thing I have every found for Tomatoes and I haven't been at it that long is compost with an additive of calcium which I get from running my egg shells through the coffee grinder. And a little epsom salt at the beginning of the season just because it doesn't hurt.

It may not have a scientific formula but it sure produces the tomatoes.

I'm busy composting right now so I have plenty for my tomato and pepper crop next year.

wouldn't it also depend on your soil quality to begin with?
I guess I'm lucky and live in an area where I can just till and put in some compost.