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ash1970_gw

Does NPK fertilizer ratio matter for determinate tomatoes?

ash1970_gw
9 years ago

Hi,

It was recommended (in the container forum) for me to re-post this question in the Tomato forum:

There are all sorts of (conflicting) advice out there about tomato fertilizer NPK ratios to maximize each stage from growth through set, fruiting and harvest - especially specific for containers or hydroponics.

I'm curious whether this matters for determinate tomatoes. In other words - just how "programmed" are determinates? Would the final results - amount of leaves, stems, flowers, fruits - be about the same no matter what NPK ratio, as long as the basic macros and micros are all there available for the plant to use?

Thanks for any comments.

-- your basic top-watering, inorganic-fertilizing, small-container-tomato first-timer

Comments (6)

  • SequoiaMatt99
    9 years ago

    I would say normal npk ratios are just fine. There's no need to be too fancy. The best fertilizer I've found for tomatoes is Espoma Organic Tomato Fertilizer.

  • digdirt2
    9 years ago

    I'm curious whether this matters for determinate tomatoes. In other words - just how "programmed" are determinates? Would the final results - amount of leaves, stems, flowers, fruits - be about the same no matter what NPK ratio, as long as the basic macros and micros are all there available for the plant to use?

    The simple answer to your question is - yes, same basic needs for all plants regardless of type.

    What is very different is those needs when grown in containers vs. grown in ground. Needs remain the same but the frequency of those needs being met increase 10 fold.

    Nutrients leach out of containers every time you water so they have to be replaced regularly - common recommendation is weekly depending on the size of container. Bigger the container the less frequent the need.

    Many also find that using liquid or water soluble supplements is far more beneficial than dry granular supplements when growing in containers. Liquid supplements can be diluted to 1/2 or 1/4 strength and used every time you water.

    Dave

  • labradors_gw
    9 years ago

    I wonder that too. I like to be organic, but organic (fish meal) takes too long and my container-grown determinants which gave me fruit in mid-June are almost finished. At least there are/were some nutrients in the potting soil and I sneaked a little finished compost on the top.

    Think I'm just going to grab the tomatoes as soon as they blush and call it a day for these guys!

    Linda

  • drew51 SE MI Z5b/6a
    9 years ago

    I use compost and fungi, and organics in containers, and results are fantastic. I will from time to time use soluable. Tomatoes are fairly easy to grow, a little harder to keep healthy. Heirlooms are a bit tougher, but worth it. As to the question IMHO yes. NPK matters, it influences the yield, grow rate, etc. Manipulating it results in higher yields. I also try and speed pollination along by vibrating the flowers. This usually results in very early tomatoes. The first flowers usually need help, I don't know if it's the cold, or lack of bees early in the year? I get mine out early with a cold frame. A huge head start.
    One of my biggest problems with a couple plants is trying to support the heavy fruit. One had so much it pulled the plant way over. Some are approaching 8 feet high now. I have one determinate and it is 6 feet. It has more fruit than any of the others, but it is done now. All are starting to ripen, about 7 were taken so far. Still loaded to the gills. It should be done in 2 weeks.

  • ash1970_gw
    Original Author
    9 years ago

    Thanks for all the interesting comments. Yes, I have been using a liquid fert (which includes micros) at a low "maintenance" concentration with every watering, for my small containers with very short determinates. And yes after the very first blossoms did not go anywhere, got a cheap battery-toothbrush, and since then almost all have set.

    Still learning, but at least the first couple of tomatoes are now starting to blush red...

  • seysonn
    9 years ago

    IMO, not that there isn't any difference between det and indet tomatoes There is not much difference between tomatoes and pepper either. Any fertilizer that is suitable for tomatoes is also good for peppers, eggplants cucurbita, etc.

    There is a new theory that almost all garden plants use NPK at 3-1-2 ratio. When all those elements are present in the medium, the plants will choose and pick what they need, provided the soil chemistry is right and balanced. In other words if we give the plant a fertilizer, in 1-1-1 ratio ( like 12-12-12) the plants are not going to use them in that order. That is why in most established gardens there is a surplus of P and K.

    This post was edited by seysonn on Thu, Jul 24, 14 at 16:45

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