If I use 16-16-16 fertilizers on my mature kiwi plants. How much and when do I fertilize.?
Clackamas County Oregon
Kiwi is pretty vigorous and doesn't require much fertilization if you already have healthy soil. However, please see https://catalog.extension.oregonstate.edu/pnw507 for recommendations. One rule of thumb is to not apply fertilizer until you see active growth (new leaves are coming out) as that is when it will help the plant the most. The publication notes that kiwi are sensitive to chlorine so please check the label for chloride salts (like potassium chloride) and avoid using that product.
Your product indicates that it is 16% N, 16% P, 16% K by weight. The publication indicates you need 1 lb of N for a mature vine that should be spread out over the growing season as it is noted you can burn the roots if you apply too much fertilizer. With the product you have that would be 6.25 lbs. (calculated by dividing .16 into 1.) However, the recommendation for P and K are not equal to that of N so you may be giving the plant more of one macro-nutrient than is recommended. The amount of K should be between 50-75% of the rate of N, P at 25-33%.