Return to the Container Gardening Forum | Post a Follow-Up

Fertilizer for container plants

Posted by sammyyummy none (My Page) on
Fri, Jun 1, 12 at 23:13

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?


Follow-Up Postings:

RE: Fertilizer for container plants

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.

RE: Fertilizer for container plants

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.

RE: Fertilizer for container plants

  • Posted by tapla z5b-6a mid-MI (My Page) on
    Wed, Jun 6, 12 at 16:32

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.


 o Post a Follow-Up

Please Note: Only registered members are able to post messages to this forum.

    If you are a member, please log in.

    If you aren't yet a member, join now!

Return to the Container Gardening Forum

Information about Posting

  • You must be logged in to post a message. Once you are logged in, a posting window will appear at the bottom of the messages. If you are not a member, please register for an account.
  • Please review our Rules of Play before posting.
  • Posting is a two-step process. Once you have composed your message, you will be taken to the preview page. You will then have a chance to review your post, make changes and upload photos.
  • After posting your message, you may need to refresh the forum page in order to see it.
  • Before posting copyrighted material, please read about Copyright and Fair Use.
  • We have a strict no-advertising policy!
  • If you would like to practice posting or uploading photos, please visit our Test forum.
  • If you need assistance, please Contact Us and we will be happy to help.

Learn more about in-text links on this page here