Plants tend to take what they need and leave the rest. If you're using fertilizer 'A' or 'B' for your tomatoes, there is no reason for you to buy fertilizer 'C' with a picture of a tomato on the box or bag.

Every plant you're apt to grow uses MUCH more N than P (6-10x more), so it's difficult to justify unnecessarily increasing the level of TDS/EC by adding huge quantities of P, huge being any % greater than N OR K. This is true for all your container plantings. 1:1:1 ratio fertilizers (like the popular 20-20-20 solubles or 14-14-14 CRFs) are already very high in P because P is being supplied at the same rate as N (this is not entirely true, because P %s are reported as P2O5, not elemental P, so you need to factor the p% in all fertilizers by .43 to see the actual amount of P in the formula. K is similar and you need to apply a factor of .83 because K is reported as K2O), or appears to be. After factoring, P is being supplied in 1:1:1 ratio fertilizers at a little less than 1/2 that of N, which is still about 3-4X more P than your plants need or can use.

Many believe that plants suddenly start using more P when they bloom or fruit, but this is not so. Plants use rather consistent ratios of all the nutrients throughout the growth cycle. IOW, if a butterfly bush is using 6x more N than P in the spring, it will be using 6x more N than P in the summer and fall, too. When it's reported that P is necessary for root/bloom/fruit growth, it simply means that deficiencies affect these organs first. It doesn't mean that over-supplying P is going to force the plant to produce more blooms/fruit; on the contrary: ANY excess of ANY nutrient is a bad thing.

To keep things easy, I use my favorite 3:1:2 ratio fertilizer on tomatoes until there is a good amount of photosynthesizing machinery (foliage); then, I reduce the solution strength of the fertilizer ans start adding in a little ProTeKt 0-0-3. This reduces the amount of N the plants receive while the 0-0-3 adds K to guard against a deficiency. Since there is already a cush in the amount of P being supplied, I don't even worry about it. I've seen no stalled growth, no evidence of P deficiencies, yields are very good, and fruit size/quality are excellent.

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5-5-5 and 10-10-10 are both 1:1:1 ratio fertilizers, 10-10-10 simply has twice as much N, P, and K as 5-5-5. 20-20-20 has 2x the NPK as 10-10-10 and 4x as much as 5-5-5. Similarly, the common soluble fertilizer 24-8-16 has twice as much NPK as 12-12-12 liquid, and about 2.5x as much as the also popular (here) 9-3-6. Again though, if a plant is using 6-10 times as much of nutrient 'A' as nutrient 'B', does it make sense to supply those nutrients in equal measure?

Another very simple strategy is to use a 3:1:2 ratio fertilizer until the plant (tomato) is well-established, then switch to a 1:1:1 ratio, which in effect is a low N fertilizer, compared to the amount of P and K being supplied.

Al

Thanks for the reply Al, do you think adding the cup of fert to the potting mix, with the 2 cups in the fert strip is to much fertilizer to start with?

bigjoe,

I am sure Al will answer your question too, but I am trialing adding a half-cup EB Stone Starter Fertilizer, plus one-half cup Osmocote CRF (18-6-12) into the 3 cups Lime approx 4" down in the EarthTainer, then 2 cups of the Old Tomato-tone in the fertilizer strips near the surface.

As I have only a 3 year supply of the Old Tomato-tone left, I will be trialing other tomato oriented fertilizers from Lily Miller, EB Stone, and other suppliers. (Darn Espoma for mucking with the Old Tomato-tone formula).

Raybo

Thanks for the replies. I have about 2 cups of the old Tomato-tone left myself that I will use in a container. Last year I just used 1 cup in my fert strip and 1 cup Lime and 1 cup Epsom salts in my SWC. I still got a lot of tomatoes off of my plants. I'm always looking to get better results, thanks.