Applying Fertilizer By Weight

[mrcasey]

Suppose that I have a Japanese Black Pine in a one gallon pot. I'd like to try adding the nitrogen component of the NPK by using blood meal. Blood meal is about 12-0-0. So, 10 grams of blood meal will give me 1.2 grams of nitrogen.

How many grams of nitrogen should I use for a tree in a one gallon pot?

 

[Glaucus]

Depends on many things. But 0.5 to 1 gram of N per a liter of potting soil is pretty good for a slow release fertilizer. Which in your case means 15 to 30 grams of blood meal for the entire season. Just for N of course. It also needs PK and trace. And blood meal decomposes in 1 to 4 months, depending on the temperature. So adding 5 gram per gallon pot 3 to 4 times a year seems a decent amount. Maybe 10 gram in late winter when it really takes 4 months to break down.
So with the other components it is probably almost a tablespoon per gallon 1 container.

 

[Glaucus]

If you were using Osmocote that is 3 to 4 month release, it has an NPK of 18-9-12. And the recommended dose for fast-growing potted plants is 3 to 5 g of Osmocote per l. That's 0.5 to 0.8 g of N per liter. So for your gallon, you'd add 1.9 to 3 gram of N to your pot. Which converted to blood meal would be 15 to 25 g per 1 gallon pot:

Osmocote Exact Standard 3-4M | ICL UK

Osmocote® Exact Standard 3-4 M is ideal for late pottings with good growing plant material and short crop cycles.

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