The ratio seems to be close, although there will be a bit more K than N. The other thing to consider is that if both of these products are organic, some of the nutrients will take time to break down and be available to the plant. How much and how long, I dont know, but from what I understand the 3-1-3 is the optimal ratio. I think your on the right track. I use a synthetic 3-1-3 ratio fert in all my SWC's and pots. Are these ferts for containers or in ground?

Damon

For containers. I'm not committed to organic but it would be nice. The ones I listed are liquid so I think the nutrient availability would be fast. I haven't actually found a fertilizer in stores yet that is 3-1-3.

Not sure I understand why you feel the 3-1-3 ratio is considered "optimal" over the more common and readily available ratios? Can I ask what is the source of this "optimal" rating is or what it is based on?

Dave

I could be dead wrong but it seems that tomatoes need quite a bit of phosphorus. That's the middle number. Too much nitrogen and you'll get aphids and whitefly. I'd recommend a slow release 10-10-10 with some bone meal mixed in just to start the garden. Later on I'd use Neptune's Harvest fish/seaweed emulsion which is 2-3-1 for NPK values. Just my opinion though. Best of luck.

digdirt & jbann23,

I picked up the 3-1-3 ratio from this thread.

I think there is a bit of misunderstanding and that is explained in more detail further down in that thread in the comments about using 10-10-10 or 10-5-10 etc.

Ratio is not the percentage of nutrient level required. The point made in that thread is that no matter which fertilizer you use, you'd supposedly need 3 parts nitrogen and potassium to each 1 part of phosphorus per that one poster's recommendation. Many successful tomato growers would not agree.

So you could theoretically use a fertilizer rated 15-5-15 or 21-7-21 etc. if such a thing existed - it doesn't.

I am not saying this is wrong, just that it is one person's opinion and would not be considered "optimal" by many. It isn't gospel. ;)

Please keep in mind that as jbann said the more commonly held belief is that phosphorus is just as or perhaps even more important as are nitrogen and potassium. Also research clearly shows that high levels of nitrogen can cause blossom drop and BER. Excess levels N can also cause huge plants with no fruit (also documented).

So, recognize that there are just as many theories out there on fertilization as there are tomato growers. Millions use 10-10-10 (1:1:1), millions also use an organic 2-2-2 (1:1:1:) but then you just have to feed 5 times as much to get the same level of nutrient. 13-13-13 (1:1:1) is common and even more use 18-18-21 (1:1:1.16). They all work when used appropriately.

Experiment and see what works best for you in your garden.;)

Dave

I agree with you digdirt. I've been looking at the MG 18-18-21 but was also trying to find an organic solution. The mix I mentioned above would be used to a level of something like 10-4-15 which seemed okay since N cheers

I am not saying this is wrong, just that it is one person's opinion and would not be considered "optimal" by many. It isn't gospel. ;)

Since I am the one who says tomatos use NPK in a roughly 3:1:3 ratio I will chime in. It isn't opinion, it is fact ;) I say this politely because I understand there are many ways to fertilize that 'work'.

Many don't use 3:1:3 ratios and who can really control it in the earth?

Nevertheless the fact remains that tomatos use NPK in a 3:1:3 ratio during their entire life cycle. Seedling, juvenile, flowering, fruiting etc. This is *known* as the result of tissue analysis of all parts of the plant.

It is very common to see 'tomato fertilizers' with the middle number, phosphorus, highest. This is 100% absurd as no plant on the planet including tomatos uses more phosphorus than N or K and many use more Calcium than P. One can find the same thing with rose fertilizers, citrus fertilizers etc. There is no plant on this planet that uses that much phosphorus. The unneeded P ends up in water bodies and contributes to eutrophication.

In the container thread I posted about this (excess P and goofy fert ratios). Here is a link to that thread for those so included. It includes the CEO of Dyna-Gro Corp (fertilizer company) admitting that the goofy formulas don't do plants any good, but they are made and sold because it's easier to give the market what it thinks it needs rather than try to re-educate it.

That it is absurd doesn't mean it doesn't work. It means that the ratio of nutrients being supplied can't be utilized by the plant in that ratio therefore much of what is supplied becomes run off waste and doesn't benefit the plant.

Yes, a 1:1:1 ratio could be used just fine. It's simply not the ratio the plant uses it in. It supplies many times more phosphorus than the plant needs and in a container environment this means it contributes unnecessarily to salt build up and then becomes run off pollution.

I just found and bought a fertilizer that looks pretty good. It is Art Knapp All Purpose soluble plant food. 20-20-20, 1lb (500g) for $6. Includes the following elements min:
B .02%
Cu .05%
Fe .1%
Mn .05%
Mo .0005%
Zn .05%

Perhaps this is all that I need, along with a bit of calcium.

justaguy2, you sticking by that theory?

It comes down to NEEDS versus OPTIMUM RESULTS.

High phosphorus (middle #) promotes more flowering as well as strong roots. These things don't show up in a tissue analysis. Also, many older methods & tests were often done on determinate field varieties, which often ripen nearly the same time, whereas indeterminates being asked to produce all season long have somewhat different needs. I've found slow & steady wins the race.

Personally, I have my very best results using a starter fertilizer like 10-60-10 or 10-52-8 for the first month, at a very reduced rate, DAILY, thru drip fertigation. Although daily, it still comes out to about the same amount recommended per week.

Then I switch to either a more balanced fert like 15-15-18 and if out of that, then the M-G 15-30-15 (now called bloom booster) or MG for Tomatoes or Schultz 18-19-30 tomato formula.

(There are reasons tomato ferts are much different NPKs than houseplants or other veggies, the #s are different for reasons. Likewise with the higher K #s for cell wall development--this can translate to higher elasticity (less cracking) too.)

When I use a high-P fertilizer instead of balanced early in the season, I consistently have plants with 30-50 fruits at a time versus 10-20 without hi-P. I'm not talking cherries either--they are in the 500-700 range depending on variety. I have beefsteak varieties that have 4-5lbs per cluster (3-5 beefsteaks/cluster), and many clusters per plant, often ripening full clusters at once,depending on the variety.

I guess it comes down to growing tomatoes, or growing LOTS of tomatoes; I try to maximize my production & size in my short season. Using hi-P ferts does that, regardless of what term papers tissue tests say.

Hi shmish,
High Phosphorus (P) concentration = most in mature stem of leaves.
When coordinate with high Nitrogen = brings P to shoots & P to fruit trusses. ( N kept up = maximum P uptake.)
Lifetime tomato use = 10-12 gr. N + 4-5 gr. P + 18 -22 gr. K.
By week 11 most tomato P is found in lower stem, adult leaf blade & in immature fruit.
Fertigation (& field irrigation) show tomato needs most K (Potassium), then more N & then P ; in that descending order.
If interested, fertigated tomatoes will consume 200 ppm K ( to leave 0 ppm) in 3 (even 2) days time.

justaguy2, you sticking by that theory?

Yes:) High phosphorus (middle #) promotes more flowering as well as strong roots.

In the same way Vitamin A promotes good eyesight ;) High phosphorus (middle #) promotes more flowering as well as strong roots. These things don't show up in a tissue analysis.

They do if the tissue analysis is done on top performing plants which is what is done when low, adequate and excessive levels are established. This also squares with other testing done where soil tests are taken before the crop and after the crop to get an idea of what the plants actually took out of the soil over the season. I guess it comes down to growing tomatoes, or growing LOTS of tomatoes; I try to maximize my production & size in my short season. Using hi-P ferts does that, regardless of what term papers tissue tests say.

If you are satisfied with your results then you should continue to do as you have been. Nevertheless there is a lot of science on plant nutrition, including tomatos and the only thing high P results in (assuming the soil already has adequate available P) is more run off into the water bodies.

If one is growing in the soil as opposed to containers things can change. There may be a reason why the P in the soil is not sufficiently available to plants. In such a case a high rate of P application may well be of benefit as it may be required to get enough P to the plant.

If you get a lab soil test done and take note of their recommendations, they will never recommend elevating P above N or K.

I was introduced to Dr. Earth Organic 5 Tomato, Vegetable & herb fertilizer by a wholesale grower who I met at a local nursery. She supplied all the tomato plants for their retail sales. She couldnÂt say enough good things about the product and highly recommended it.

I have used it for five years with great results on tomato production. It has a 5-7-3 ratio plus the following:

Pro-Biotic beneficial soil microbes
Ecto and Endo Mycorrhizae
Calcium 7.96%
Sulfur 2.8%
Primary and secondary nutrients derived from:
Fish bone meal
Feather meal
Kelp meal,
Alfalfa meal,
Soft rock phosphate,
Fish meal,
Mined potassium sulfate
Seaweed extract

ItÂs a granular formula that is mixed into the top few inches of soil. I also have made a tea out of it and foliar fed all my tomato plants over the summer. For example, I have five plants that were planted on 3-25-09, all of which are between 2 ½ to 3 ½ tall. Each plant has an abundance of flowers and numerous fruit set. FYI the plants are Caspian Pink, Purdens Purple, Golden Jubilee, Pink Ping Pong, and Sweet 100.

I collect leaves from my Japanese Maple trees in the Fall and spread them over my raised planter beds to decompose over the winter. At planting time in mid to late March I turn them into the soil. I also stir the planter beds on occasion during the over-winter.

However, IMHO, the weather has a lot to do with exceptional tomato production.

I have used it for five years with great results on tomato production. It has a 5-7-3 ratio plus the following:

Please write to them and say this:

"I am a huge fan of your products, but don't see any science supporting the high P ratio of your fertilizer (name the fert here). I am trying to understand which of your ferts to use. Would you please explain to me why I would want the high P formula instead of one of your others?

Post their response here the way I did for DynaGro.