Tomato feeds with very low NPK - are they any good?

Discussion in 'Edible Gardening' started by Engelbert, Jul 19, 2025.

  1. Engelbert

    Engelbert Gardener

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    Hi gardeners

    I usually use homemade comfrey tea on my tomatoes, but this year I've not had the time to "brew" any and I've just finished off the old lot (which I've since found was probably too old and therefore likely lacking in nutrients).

    So I'm looking to buy some feed for the first time and spent a little time looking this evening. I'd like to use organic and I am only looking at vegan options.

    Some of the ones I've found that look good have very low NPK. I found one that is 2-6-4, already quite low, but then some that are 0.xx for all three. And yet they are sold as tomato feeds. From what I've read, toms need much higher NPK percentages. So I wondered if I'm misunderstanding something and/or how these very low NPK feeds can be effective?

    More generally, if anyone has a recommendation for organic vegan feed I'm all ears :)

    Many thanks
     
  2. Pete8

    Pete8 Total Gardener

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    N-P-K numbers can be confusing.

    NPK at 2-6-4 is low, but the dosage may be higher to compensate.
    NPK at 4-12-8 is medium-high so the dosage would be lower.
    So you'd use twice the amount of the 2-6-4 fertilizer than you would a 4-12-8 fertilizer to get the same strength of fertilizer. This would be taken into account on the dosing instructions.

    Organic feeds will have a lower NPK values simply because they are organic and that is the nature of organic fertilizers.
    I use Chempak 4 for tomatoes which has NPK 15:15:30 as it's all chemicals.

    As far as the plants are concerned, it makes no difference.
    There is no such thing as an organic nitrogen molecule or a non-organic nitrogen molecule - they are identical in every way. Every nitrogen atom in the universe is identical, the same goes for all of the elements.
     
  3. infradig

    infradig Total Gardener

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    NPK numbers are ratios; not emperical units. There surely is a conflict in seeking both organic and 'vegan' properties?
     
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    • Butterfly6

      Butterfly6 Total Gardener

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      The only vegan one I can think of without researching, other than hone-made (comfrey, weed etc) would be based on seaweed.
       
    • hi2u_uk

      hi2u_uk Gardener

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      oh this is interesting , i use tomorite which is NPK 4-3-8 . It didnt realise this was considered low. I may have over diluted it because i was worried when it said on the label that it was a concentrate so was worried about giving too much to the plants.
       
    • Butterfly6

      Butterfly6 Total Gardener

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      If you’re following the advice on the label, your plants are getting the right amount @hi2u_uk . As @Pete8 says the dosing instructions will differ between products
       
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      • infradig

        infradig Total Gardener

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        But seaweed is naturally growing upon materials of waste from fish, animals ,birds (and, regrettably) humans so is not 'vegan'.
         
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        • pete

          pete Growing a bit of this and a bit of that....

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          I didn't even know there was such a thing as vegan fertiliser, I do get the idea that blood fish and bone is probably not vegan although it is organic.

          Surely if you stick to standard chemical fertilisers you will be getting a vegan product.
           
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          • Butterfly6

            Butterfly6 Total Gardener

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            Quite right, but that would be a very long rabbit hole to go down with some very skinny vegans!
             
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            • infradig

              infradig Total Gardener

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              Not very 'organic' though is it ? A (19th-)Twentieth century problem ?
              But yes it was the shortage of guano that prompted the Haber Bosch process to create commercial quantities of ammonia etc. from which 'artificial fertilizers' are made.
              This is the dicotomy facing those of a persuation that ignore the laws of nature, disregard the carbon and water cycles and believe that science can be 'settled'
              Life is not sustainable on strictly 'vegan' principles for a human population of 13 billion plus; one has to be particularly 'self entitled' to think it could.
               
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              • pete

                pete Growing a bit of this and a bit of that....

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                I missed the part that it had to be organic as well.:biggrin:
                 
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