I'm using an organic liquid fish fertilizer (3-3-0). The instructions say to dilute 1 Tablespoon in a gallon of water, every two weeks for vegetables. But it isn't clear how many plants this will feed.

This will depend on how much my plants really need, but I'm looking for a ballpark -- wondering if I'm spreading it too thinly. Is a 1 gallon feeding good for:

  • 2 cabbages, or
  • 20 cabbages, or
  • 50 cabbages?

Not that I have 50 cabbages... just want a benchmark application rate.

(For anyone reading my other question about nutrient imbalance, this application is to a newer garden with very different soil analysis.)

  • 1
    this is a tough question, because most fertilizers are labeled in this manner. I guess they assume everyone's growing the same amount!
    – JonH
    Commented Jun 17, 2011 at 13:58
  • ...and watering the same amount.
    – winwaed
    Commented Jun 17, 2011 at 14:38

1 Answer 1


After asking the question I was thinking about it more. It seems obvious now.

The fertilizer is 3% nitrogen, 3% phosphorus.

It calls for a tablespoon in a gallon of water. That's about 0.004 gallons of fertilizer. Assuming for simplicity that the fish fertilizer has the same density as water, 8.35 lb/gal, that's 0.033 pounds of fertilizer, or 0.001 pounds of nitrogen.

If my soil test called for 2 pounds of nitrogen per 1000 sq ft (for the season), that's 0.002 lbs per sq ft.

If I apply every two weeks as marked on the package over my growing season that's about 7 applications. So over the course of the season that feeds about 3.5 sq ft of garden, give or take.

So it looks like the answer is that a gallon of diluted fertilizer is about enough to feed 1-2 cabbages for two weeks.

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