Monday, May 13, 2019

Homemade low-ammonia, high-calcium fertilizer for tomato plants

This fertilizer is designed to have high calcium but minimal ammonia.  The plants need calcium to minimize end-rot, but ammonium ions have been reported to interfere with calcium uptake.


• 2 cups Hi-Yield Calcium Nitrate Can buy on Amazon.

• 1 cup 26-0-4 Vigoro lawn fertilizer; its nitrogen is mainly in the form of urea, not ammonium nitrate like many other fertilizers

• 1 cup Triple Super Phosphate 0-46-0, from Easy Peasy Plants.

• 10 cups wood ash.  I made this the old-fashioned way in my fire pit.  Wood ash has about 5% potash  (potassium) and about 1% phosphate, and as a bonus has a lot of calcium - up to 25% calcium carbonate. An alternative could be Espoma potash 0-0-60 6 lbs.   

This should make 14 cups.  I estimate this to have a makeup that is very close to 4-4-4 NPK, and is ~5% calcium.   Use 1/2 cup per 5 gal of planting medium.   

In practice, I carefully measure this "14 cups" but in the end I measured out 6 batches of 3 x 5 gal and it was gone, so I only got about 9 cups out of it !  I believe that when I thoroughly mixed the ingredients it compressed together, so I should have probably re-measured the whole batch and adjusted accordingly.  This means that I may have overshot the fertlizing by about 50% or so.

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