"Read somewhere"? So obviously it's TRUE because everything printed somewhere is 100% reliable information. **

Because K (Potassium) and P (phosphorous) are not gasses, they will be all over in the soil.

And the answer to the fertilizer is "it depends".

** More seriously, if you can't remember where you read something and can't find that information in a reliable gardening source, it's probably false.

Foliar fertilizer is no different from any other type of fertilizer so will work the exact same way as any other soil applied fert would. As it is a liquid, it will soak down into the soil in proportion with the amount of liquid applied.

The foliar application only needs sufficient time to dry on the foliage for absorption but is considered a rather inefficient means of supplying needed nutrients. There is a limit how much plants will absorb from foliage - most nutrients are taken up from the roots.

Myth of foliar fertilizing.

If it's already dissolved it's going to penetrate the soil just fine. Note, we have been using granular (not even dissolved!) fertilizers for decades by sprinkling them on top of the soil, and they work fine. It's true that P especially is not highly mobile especially in clay soils, but I have clay soil and had to treat my fruit trees when they were young because they didn't bloom and fruit. I scratched bone meal in around trees and next year I had fruit.

I just wanted to be efficient in plant uptake and it seems I have been doing it wrong for all these years ... :) Only applying foliar instead of root fertilizer and in the middle of the heat, not even during the evening.

From what I read, looks like foliar treatment is more beneficial for a quick re-animation of a dying plant, but for proper growth stimulation the soil solid fertilizer should be applied. But what if I poured this foliar (dissolved, for better penetration. Or should I leave it undissolved ?) right into the ground, hmm. I am talking about a 17-6-18 NPK with lots of micro nutrients. And my targets are some yews. Hmm, and some roses too.

A foliar fertilizer is just one in liquid form so it can be sprayed on the plant. Or poured on the ground :-) But if intended as a liquid application, it must be dissolved/mixed in water and at the appropriate dosage :-) You never want to apply a water soluble powder dry to the soil. Or at anything more than the suggested dilution rate (less is fine).

Excess Nitrogen, especially soluble N flows quickly out of the soil and into the ground water where it is a pollutant.

What does a good reliable soil test say about the nutrients in the soil these plants are growing in? Putting more fertilizer into a soils that has adequate amounts does not help and may cause more problems because excess levels of nutrients can cause plants to not use other nutrients. Excess soil Nitrogen levels can cause lush plant growth that is very attractive to several insect pests.

Before adding more fertilizer, of any type, be sure the plants need it.

kimmq is kimmsr

Hmm.. Never thouht about testing the soil :d Seems like a good idwa, but will the soils stay the same over the years ? I doubt that. It is just an improperly cared for urban garden just as the rest of the urban landscape is. This is not a proper ecosystem looked after by nature, but rather by people. And we all kbow what happens where man sets foot :)

Are you adding compost or decomposable mulches? How is the organic matter content? You shouldn't need much fertilizer if you're taking care of that. In any case gardengal has it right, you can water with liquid fertilizer just as well as spraying it, it's basically the same stuff.

You shouldn't have to worry about polluting groundwater unless you're adding huge amounts over a large area and the soil is very silty/sandy. It's more of a stormwater runoff problem for most urban yards. We humans do use way too much fertilizer, as a general rule, especially in our yards.

Every homeowners little bit of excess fertilizer combines with every other homeowners little bit if excess fertilizer to become a large contributor to the pollution problem. The toxic algae bloom in Lake Erie last summer was not just caused by farm runoff, but the total use of excess fertilizer in the basin.

Soil testing is an aid in keeping the use of excess fertilizer under control and is one reason why some states have banned applying Phosphorus without one. Soil pH does not stay the same and soil nutrient levels vary, so a good reliable soil test, every few years (no need for one every week or month) can be a good aid in making a good healthy soil that will grow strong and healthy plants. A good reliable soil test might also save you some money if it shows you do not need to spread that fertilizer.

kimmq is kimmsr