Specialty Gardening: Fertilizing, 1 by tapla

tapla wrote:
PC - you didn't do anythinf wrong by applying the fertilizer to the soil/roots. Here are a couple of blurbs I wrote for and left on another forum site:

Some parts may seem off topic or might overlap what I already offered.

If you actually do NEED to supply nutrients via foliar applications for houseplants, there is either something gone awry with your nutrition supplementation program or there is a culturally induced deficiency, usually caused by the soil. Foliar applications are effective at supplying nutrients when they are both scarce in the soil and the plant is growing so robustly it cannot assimilate them quickly enough to allow it to grow at its genetic potential. More on this later, but there really is no reason you cannot supply all the known essential elements in one application to the soil, with a single product.

If you ARE using a fertilizer that supplies only a few of the minor elements, then a second application of a micro-nutrient preparation is advisable. Some lack several of the minor elements, and most soluble fertilizers lack both Ca and Mg, so these elements need to be considered, especially in aging soils.

It's best to supply nutrients in the same ratio that plants use them, unless you are using nutrition to induce a particular growth-related result. If you take an average of the ratio of NPK that a huge % of plants use, you'll find that they use it in a ratio of approximately 10:1.5:7. (ratios are different than the %s reported, though they are related) Since fertilizer formulas report phosphorus as P2O5, not actual phosphorus (P), and potassium is reported as K2O, not actual potassium (K), to convert P2O5 to actual P supplied, multiply the P2O5 value by 0.43, and to convert K2O to actual K supplied, multiply the K2O value by 0.83.

I said all that technical stuff so I could say that .... after the math is done, almost all plants use nutrients in something extremely close to a 3:1:2, NPK ratio, so fertilizers like 24-8-16, 12-4-8, and 9-3-6 (all three are 3:1:2 RATIOS) are excellent choices for almost all plants if your goal is normal growth.

and ....

The effectiveness of foliar fertilizers varies to the extreme. First, only some plants can absorb ions (and a few small proteins of little significance) through their cuticle and allow them to enter the nutrient stream. This means that only soluble solutions or the tiny ionic fraction of organic fertilizers like fish emulsion are able to pass through the cuticle of SOME plants and make it to the nutrient stream. Fish emulsion depends on micro-organisms in the soil to break it down into elemental form so it can be absorbed. These organisms are not present in measurable populations on foliage and would lack the moisture necessary to keep them viable anyway, so foliar applications of FE and other organic amendments are not measurably effective as a foliar spray.

To answer your question directly: Any fertilizer that supplies nutrients via foliage as the primary pathway would supply the same nutrients via normal root pathways.

Note that many nutrients are immobile in the plant (mostly micro-nutrients and Ca), so quick fixes like adding Fe (iron) via foliar applications may green up the leaves temporarily, but do nothing to actually relieve the deficiency the entire organism is dealing with.

Al

This may be helpful: http://davesgarden.com/community/forums/t/783660/