Fertilizer for container plants

sammyyummy(11)June 1, 2012


I recently got a fertilizer from a friend. It was listed as ammonium phosphate 16-20-0 NPk ratio. My plants are annual flowering types.

Is this ok to give to 4-6wk old seedlings?

Is this ok to give established annuals?

What fertilizer and NPk ratio should I look for in fertilizers for seedlings? And established annuals?


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Ohiofem(6a Ohio)

This is not a good fertilizer to use, especially with young annuals. A better choice would be a fertilizer that has all three major nutrients (N-P-K) plus trace minerals. Many people on this forum prefer a fertilizer that is has three times as much Nitrogen (N) and two times as much Potassium (K) as as Phosphorous (P). One you might be able to find would be a version of MiracleGro that is 24-8-16.

    Bookmark   June 2, 2012 at 7:10PM
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What fertilizer and NPk ratio should I look for in fertilizers for seedlings? And established annuals?

My brain always tells me to go with a balanced fertilizer (7-7-7 or 13-13-13, etc.).

I guess the best answer is to do a soil test and fertilize each plant based on their specific needs, even to the point of using several different fertilizers. In the end, that makes me dizzy so I tend to gravitate towards the balance stuff.

    Bookmark   June 5, 2012 at 6:26AM
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tapla (mid-MI z5b-6a)

You're not alone in the way you think, but plants don't USE nutrients in a 1:1:1 ratio, so it makes little sense to supply it that way. Plants tend to use nutrients in a ratio that varies surprisingly little from plant to plant. What varies is the o/a amount of nutrients various plants require. On average, plants use about 6X more N than P, and about 3/5 as much K as N. When the calculations are done that adjust for the fact that the P & K % reported aren't the actual amounts of P & K IN fertilizers, you'll find that fertilizers with 3:1:2 ratios come closest to supplying nutrients in the ratio at which plants actually use them. There is a decided advantage in using a ratio that mimics usage because it allows you to fertilize at the lowest level possible w/o deficiencies. Examples of 3:1:2 ratio fertilizers are 24-8-16 made by Miracle-Gro and many others, 12-4-8 Miracle-Gro, and Foliage-Pro 9-3-6, which is favored by many on the forums.


    Bookmark   June 6, 2012 at 4:32PM
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