The jury is out on foliar feeding. Many sources say it can rapidly correct nutrient deficiencies, others say it can't.

Many sources claim natural/organic products like fish emulsion repel pests or can prevent/clear fungal infections, others say no way.

In other words I don't think you will find any advice on 'how to' do it that isn't contested by another source.

Use a water soluble plant food such as Miracle Grow at the recommended strength. For best results add a wetting agent. If possible, spray the under sides of leaves with a fine mist. I can't give you any schedule, use your best judgement.

In my opinion, the plants will absorb only a small amount of nutrients through their leaves. They will absorb more through their roots from the nutrients which drip onto the soil.

Jim

I foliar feed with well diluted compost tea and also with 1/2 strength fish emulsion fertilizer alternate weeks. I use a hose end sprayer - the kind intended for insecticide application (about $2.50 at Walmart). It applies it in a misted wide fan spray pattern.

Apply early in the AM only, never in bright sun or the high heat of the day. Don't drench the plants, just spritz it from the bottom up to get the undersides of the leaves. It doesn't replace root feeding but just supplements it.

Dave

You mention compost tea. There is a lot more benefit to foliar spraying with a well-prepared compost tea. The subject is long and somewhat technical, which is why I'm not fully up-to-snuff on it. But it's mostly about the interaction the micro-organisms and the plant and how they actually benefit one another.

A weak solution of Miracle Grow sprayed onto the foliage is supposed to benefit the plant in regards to "FOOD" only. Whereas the compost tea provides much more than a "simple feeding".

I have seen statements that any nutrient source will result in feeding the microherd on plant leaves, not just compost tea. It's the same with fish emulsion or Miracle Grow.

Of course, that's what I heard and doesn't make it so.

The rationale for this is keeping as high a population of non harmful microbial/fungal life on the plant tissue to make it harder for pathogens to infect the plant.

How well does it work? Who knows.

I think it is largely a marketing gimmick to help sell water soluble fertilizers. Plants have not evolved to efficiently pull nutrients in through their leaves, due to the fact the nutrients are in the soil not in the air.

Sorry it took a while to find this but - Just for your reading pleasure ;) here is a link to a study on the possible benefits of foliar feeding done by some folks here at GW back in 2005. Some great pics compare results.

I don't offer this as any definative proof - but it is fairly scientific and some interesting reading.

Another good read on the subject is Foliar Feeding

It is based on hydroponic plants but many of the stresses it discusses are also common to the garden.

Here is a link that might be useful: Forums - Foliar Feeding tomatoes

Thanks everyone for the great replies, especially the thread from last year. Now to be even more specific, I don't use chemical fertilizers (with only one exception and thats on my brugmansia plants) other than the brugs, everything else gets either alfalfa pellets and fish emulsion, and/or compost tea, but that is not done by foliar feeding, only root feedings.

Right now I have a bucket of comfrey leaves steeping in water, and will be diluting that 20 parts water to one part comfrey tea and will try to foliar feed a few of the tomato plants so see the effects of the comfrey. Thanks again for the replies.
Alberta

And I thank you, digdirt, for finding that thread about my foliar feeding experiment. I tried searching without success, and figured it must have dropped off the forum.

I accept "fairly scientific" as an accurate description of the experiment.

Jim

I love comfrey tea as a foliar treat.

The answer is that it depends on the plant and and what you're feeding it with. It should never be substituted for quality soil and as with all fertilizers, more is not better and should only be considered as a supplement. I too do not use chemical treatments since I have natural resources.

Foliar Feeding by Linda Chalker-Scott, Ph.D., Extension Horticulturist and Associate Professor

Foliar Fertilization a lengthy article

Much has been published on foliar feeding. However, if you read the published information carefully (a tedious process), you will see that very little is based on experimental data. Much of it cites the experiments performed by Tukey in the 50's. Other than that, there is lots of speculation.

The biggest unanswered question I had, and still have, is whether any of the experiments controlled for dripping of the foliar fertilizers onto the soil, resulting in root feeding as well as foliar feeding. Except for my own experiment, which did carefully control that, I was unable to find this mentioned in any of the experimental procedures.

As with many gardening practices, psychology plays a big role. If foliar feeding brings a happy feeling to the gardener, maybe it's worth doing, whatever the effect on the plants.

Jim

Foliar feeding definitely has an impact. Think of the effect "patches", topical applications of medications, or even poisonous plants have when they come in contact with your own skin. There is more than psychology involved here. If in doubt, do your own control study. Spray half with compost or comfrey tea and leave the other half of the same variety alone. Then judge for yourself.

Your experiment was a comparison of foliar feeding versus no fertilizer at all. The result is that foliar feeding produces somewhat taller plants than no feeding. That shows there is some effect but not much of a difference. It tells us nothing about the relative efficiency of foliar feeding, except to suggest that it is an inefficient method (treated plants were only 13% taller than "no fertilizer").

I would have liked to see foliar feeding versus root feeding, of the same amount of fertilizer applied to each group. That is more practical for the gardener.

You buy $1 worth of fertilizer: now what is the best way to apply it for maximum plant growth? I think you are far better off applying it to the root zone.

"If in doubt, do your own control study."

You may have noticed that I did my own study. It required all the effort I was willing to invest. If you want to test another theory, please do. Be sure your experiment is not designed to prove your theory, but to test it. Design the experiment carefully and report on it in detail. I would be interested in the results.

kubotabx2200, my experiment was limited to the narrowest question I could ask. The question was "can plants make any use at all of fertilizer applied to the foliage?" Readers of the thread raised many other questions such as yours, which is a valid question. I was not prepared to deal with too many variables however. I'll leave that to others.

Jim

For those who missed the link to the Foliar Feeding Experiment, here it is.

Thanks again, digdirt, for rescuing it from oblivion.

Jim

Here is a link that might be useful: Foliar Feeding Experiment

You're welcome Jim. ;) It was one of my bookmarks from way back then. Got a bunch of good ones saved from as far back as 1999 - long before iVillage bought out GW - but my bookmarks are in as bad a shape as the search here. Once I found it I bumped it up on Garden Experiments so it will be around awhile longer.

I thought then (and still do) that it was a very worth while study.

Dave

OK I will start a new thread Non-Foliar Feeding but instead of a 4 week experiment all I can offer is "field observations" of my outdoor tomato planted exactly 5 weeks after planted from seedlings that were 3-4" above ground when planted 5 weeks ago.

I took some measurements and photograph about 15 minutes ago and I am uploading them now and I will describe how I grew them.

Good for you, kubotabx2200! We gardeners have all sorts of opportunities to do simple experiments but we seldom do them.

Just trying out something different and guessing how well it worked doesn't constitute an experiment. We do that all the time with uncertain results. It needs to be a little more methodical.

Have fun!

Jim

P.S. Nice tractor!

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