Foliar Feeding

jimster(z7a MA)April 25, 2005

The practice of foliar feeding has been a subject of curiosity to me for many years. Roots are made for absorbtion of water and nutrients aren't they? And aren't leaves made for photosynthesis? Can leaves really absorb water and nutrients well enough to benefit a plant?

This experiment was begun on 04/16/05 to see if a difference in growth rate could be noticed between 5 tomato seedlings which are being given foliar feeding and 5 which are not.

Jim

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jimster(z7a MA)

Claims for, or against, the effectiveness of foliar feeding of plants range from "Foliar applied nutrients are one hundred to five hundred times more effective than root nutrition" (3) to "Nearly all plants are capable of absorbing nutrients through the leaves. This works well for nutrients that are needed in small quantities, but is very expensive and not very effective for nutrients that are needed in large quantities." (11) For large quantities of nutrients to be absorbed, foliar feeding must be applied far more frequently than root feeding. (6)

As well as a lack of concensus as to itÂs effectiveness, the mechanism by which nutrients enter the leaves is in question. "The moisture is absorbed straight into the leaf via the leaf cuticle, through the stomata" (4) according to one source. Stomata are located on the underside of the leaf. Stomata are open during the day and close at night. Another source (6) claims that, in the case of turf grass, "stomates play no role in foliar feeding" but that fertilizer is "absorbed through tiny cracks or pores in the surface of the leaf surface in the wax layer. These pores are very, very small tubes, and are lined with water. They are called transcuticular pores." (6)

Whatever the mechanism, there is agreement that nutrients, or at least some nutrients, can be absorbed by leaves. Some sources indicate that plants benefit sigificantly only from absorbtion of elements such as Zn, Mn, Fe, etc. and that foliar feeding of N, P and K is not an efficient method. (11) Even Zn, Mn and Fe may need to be chelated to pass through the tiny pores of a leaf. (6)

The most widely agreed upon benefit of foliar feeding is that nutrients can more quickly reach all parts of the plant than by root feeding. This was established in a well known experiment performed in the 1950s by the noted horticulturist, H.B. Tukey at Michigan State Universtiy, using radioisotopes to trace the movement of nutrients through plants. (9) So foliar feeding may be useful for quick correction of some nutritional deficiencies in crops. (3) (4) (7) (8)

(1) http://www.vg.com/gardening/content.asp?copy_id=5161
(2) http://www.ecke.com/html/tibs/tib_foliar_feeding.html
(3) http://www.planetnatural.com/site/xdpy/kb/00031/index.html
(4) http://www.abc.net.au/gardening/stories/s237862.htm
(5) http://www.au.gardenweb.com/forums/load/roses/msg0206545231835.html
(6) http://cals.arizona.edu/turf/ccps101.htm
(7) http://www.ag.ndsu.nodak.edu/aginfo/procrop/fer/folfed05.htm
(8) http://www.atlanticfec.com/4.htm
(9) http://www.ext.vt.edu/news/periodicals/commhort/2002-11/2002-11-03.html
(10) http://www.uas-cropmaster.com/sptips.htm
(11) http://www.ag.uiuc.edu/archives/experts/fertility/0384.html

    Bookmark   April 25, 2005 at 4:58PM
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jimster(z7a MA)

Ten seedlings of Box Car Willie tomatoes were randomly assigned, five each, to N (no foliar feeding) and Y (foiar feeding). The plants averaged 2.43" tall at the start of the experiment and are potted in ProMix BX in 8 oz. styrofoam cups with drainage holes. Growing ight is provided by 2 - 40W cool white flourescent tubes.

Two solutions were prepared, one gallon of each. Solution A is distilled water with five drops of liquid detergent as a wetting agent. Solution B is distilled water with five drops of liquid detergent as a wetting agent and 0.5 ounce of RA-PID-GRO soluble plant food. RA-PID-GRO is a 23-19-17 fertilizer which also contains boron and chelated copper, iron, manganese and zinc.

Twice each week, foliage of plants assigned to N are sprayed with a finely atomized spray of solution A. Foliage of plants assigned to B are sprayed with a finely atomized spray of solution B. Top and underside of foliage is sprayed. Care is taken to prevent either solution entering the soil. Plants are kept horizontal until dry to prevent solutions dripping into soil. Soil moiture is maintained by watering when necessary with tap water applied directly to the soil.

The seedlings are measured weekly for height to tallest central growth. The plants are photographed weekly.

    Bookmark   April 25, 2005 at 4:59PM
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jimster(z7a MA)

Height of Plants (inches)

...................Avg.......Avg.(N)......Avg.(Y)

4/16/05......2.43..........2.46..........2.40
4/23/05......3.86..........3.90..........3.83

    Bookmark   April 25, 2005 at 5:07PM
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jimster(z7a MA)

    Bookmark   April 25, 2005 at 5:09PM
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jkirk3279(Z5 SW MI)

This looks like a fun experiment.

Except ... how far are your seedlings from the light source?

I know, if it's the same-same for both groups it shouldn't matter but the plants need light to power everything. So your results might be a bit slower coming if the light levels are too weak.

Is air circulation the same for both groups?

The 'wetting' agent... dish soap? Too much soap could be harmful to the plants and terminate the experiment early.

I would consider Neem oil or other horticultural oil as your wetting agent. Coconut oil is suggested by one vendor I have used. Basically a surfactant.

You're using metered sprays to control the amounts of mist sprayed on the plants?

    Bookmark   April 27, 2005 at 12:12AM
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vgkg(Z-7)

Thanks for doing all this work Jimster, please do keep us posted of what works and what doesn't. Interesting season ahead. vgkg

    Bookmark   April 27, 2005 at 12:13PM
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jimster(z7a MA)

You make some good observations, Jkirk.

The lights are placed close to the plants except when photos are being taken. They are moved up for photos so that, as the plants grow, the photo set-up can remain the same for easy comparison. I wondered if someone would ask about that. :-)

Likewise, the plants are spaced further apart in the photos to allow for future growth. Normally, they are together on the same shelf, so receive the same ventilation, etc.

Yes, the wetting agent is dish soap. Only a few drops were used. It is not very effective. This and some other conditions of the experiment could be changed I think, without invalidating the experiment.

I have no way of metering the spray, but I am confident, by careful observation, that the average amount of solution adhering to the foliage is quite consistent among plants.

Thanks for your interest.

Jim

    Bookmark   April 27, 2005 at 12:21PM
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jimster(z7a MA)

Because tomato seedlings are used as subjects in this experiment, I started a thread in the Growing Tomatoes Forum. Normally, I would not establish two threads on the same topic. In this case though, I think the Gardening Experiments Forum is the right place to post the experiment, so all experimenters will find it, while a thread in Growing Tomatoes will serve the tomato enthusiasts.

Jim

Here is a link that might be useful: Growing Tomatoes Forum

    Bookmark   April 27, 2005 at 12:51PM
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jimster(z7a MA)

Because tomato seedlings are used as subjects in this experiment, I started a thread in the Growing Tomatoes Forum. Normally, I would not establish two threads on the same topic. In this case though, I think the Gardening Experiments Forum is the right place to post the experiment, so all experimenters will find it, while a thread in Growing Tomatoes will serve the tomato enthusiasts.

Jim

Here is a link that might be useful: Growing Tomatoes Forum

    Bookmark   April 27, 2005 at 1:23PM
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nandina(8b)

Jim,
I am following your experiment closely both here and on the Tomato Forum. May I suggest that you try a very gentle, organic wetting/sticking agent which can be purchased at health food stores known as Yucca extract. It is also available in a capsule form which can be cut open and a bit added into your liquid concoctions. As you know, yucca root has been used as a soap for centuries. I don't think that making this switch would affect your experiment. Yucca extracts have been certified safe for human consumption.

    Bookmark   April 27, 2005 at 4:05PM
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jimster(z7a MA)

Thanks for the suggestion, Nandina.

I am considering several changes which I think would not affect the experiment. After all, my only objective is to find out if foliar fed nutrients do indeed penetrate the leaf in some way. At this point, I am not concerned with their effectiveness, except as an indicator that they were absorbed into the foliage.

Jim

    Bookmark   April 27, 2005 at 5:57PM
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lisa2(coastal CA)

awesome experiment!

    Bookmark   April 29, 2005 at 3:45PM
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jimster(z7a MA)

Height of Plants (inches)

...................Avg.......Avg.(N)......Avg.(Y)

4/16/05......2.43..........2.46..........2.40
4/23/05......3.86..........3.90..........3.83
4/30/05......4.75..........4.78..........4.73

    Bookmark   May 1, 2005 at 4:04PM
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jimster(z7a MA)

    Bookmark   May 1, 2005 at 4:13PM
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jimster(z7a MA)

One change in procedure was made this week. Realizing that the foliage remained dry most of the time, and could only absorb foliar fed nutrients when wet, I decided to spray all the plants daily with solution A (no nutrients) This is intended to allow further opportunity for absorbtion of nutrients previously deposited on the foliage. Bear in mind that the only objective of the experiment is to determine if any evidence of absorbtion can be observed. No attempt is being made to measure the amount of absobtion.

Comments have been made that perhaps increase in height is not the best variable to measure the effect of foliar feeding. This measure will be continued, but other variables, such as leaf color, are under consideration.

Jim

    Bookmark   May 1, 2005 at 5:07PM
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jkirk3279(Z5 SW MI)

If you want to be sure that foliar feeding works, pick one plant and hit it with a dilute spray of Epsom Salts.

You'll see results.

I still like the idea of a light sensor/LED test jig.

    Bookmark   May 2, 2005 at 12:56AM
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silybum(Sunset 16/z8b)

If you would decide to use yucca extract to replace the liquid detergent, take note, yucca extract not only makes sprays stick to crop foliage, it is also a great nutritional foliar in itself. (according to Peaceful Valley Farms, where I purchase my fertilizers). They sell it as Therm X70.

Here is a link that might be useful: Peaceful Valley Farms

    Bookmark   May 4, 2005 at 8:11PM
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jimster(z7a MA)

Well, at $100 per gallon, I guess I won't be using yucca extract. Thanks for the link though. I'm saving it for future reference.

Jim

    Bookmark   May 5, 2005 at 11:14AM
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jimster(z7a MA)

Height of Plants (inches)

...................Avg.......Avg.(N)......Avg.(Y)

4/16/05......2.43..........2.46..........2.40
4/23/05......3.86..........3.90..........3.83
4/30/05......4.75..........4.78..........4.73
5/07/05......6.74..........6.55..........6.94

    Bookmark   May 11, 2005 at 9:15PM
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jimster(z7a MA)

    Bookmark   May 11, 2005 at 9:56PM
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jimster(z7a MA)

"If you want to be sure that foliar feeding works, pick one plant and hit it with a dilute spray of Epsom Salts.

You'll see results."

OK. Let's try. I added a teaspoon of Epsom Salts to Solution B (the nutrient solution). We will see any results in next week's report, at the earliest.

So far, I have observed no noticable differences between the two sets of plants.

Jim

    Bookmark   May 11, 2005 at 10:03PM
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jkirk3279(Z5 SW MI)

I usually use 1 tablespoon Epsom Salts per gallon of water.

Have you come up with a green-ness test yet?

    Bookmark   May 11, 2005 at 11:13PM
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jimster(z7a MA)

I haven't come up with a green-ness test. Just using visual evaluation I thought for a while there was a difference in color. Now, however, I detect no visual difference.

All the plants are growing well at the same rate, so far as I can tell. Their color could be better and I truly wish I could give them just a touch of root feeding.

Jim

    Bookmark   May 12, 2005 at 11:25AM
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jkirk3279(Z5 SW MI)

I hit some of my plants with Epsom Salts spray two days ago, and one in particular turned dark green overnight.

Now, I admit, I never ran trials like you are doing. For all I know, Magnesium Sulphate can only be absorbed by roots.

I mention this because I forgot the whole point and watered with the solution.

Which invalidates the test, I suppose.

But I've always been too greedy for success to feed only half my plants.

    Bookmark   May 13, 2005 at 1:48AM
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jimster(z7a MA)

I think it is rare that foliar fed nutrients do not end up in the soil. In practice, that's fine. If it works, do it. But, because of that, all the anecdotal evidence of success with foliar feeding under normal growing conditions does not satisfy my curiosity about whether foliage actually absorbs nutrients. Most, if not all, the benefit may be from the stuff that eventually drips into the soil.

Some, if not all, of the science which has been done re foliar feeding must have taken this into consideration. In my cursory search of the literature however, I found no discussion of it.

"But I've always been too greedy for success to feed only half my plants."

That is the primary reason we gardeners perform so few experiments, in the scientific sense. We want to give all our plants what we believe to be the best treatment. If our plants do well under that treatment, we are happy and attribute the success to what we have done. And why not?

Jim

    Bookmark   May 13, 2005 at 12:52PM
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rockymountainchile(z5 CO)

Jim,
you could always seal off the top of the containers while foliar feeding, this would eliminate another variable in your tests... any recent updates, measurements, or photos?

Jack

    Bookmark   May 17, 2005 at 1:25PM
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jimster(z7a MA)

"...you could always seal off the top of the containers while foliar feeding..."

That's what I am doing, Jack. Also, I keep the plants horizontal until dry, so nothing drips into the soil. I haven't yet found out if other experimenters have done that. I think they must have but, if the plants were field grown it wouldn't be easy.

Update is coming soon.

Jim

    Bookmark   May 17, 2005 at 2:36PM
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atillathepun(Sunset Z15 CA)

Suprised there hasn't been an organic/chemical foliar comparison, such as compost tea vs commercial foliar plant food.

    Bookmark   May 18, 2005 at 6:40PM
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jimster(z7a MA)

Height of Plants (inches)

...................Avg.......Avg.(N)......Avg.(Y)

4/16/05......2.43..........2.46..........2.40
4/23/05......3.86..........3.90..........3.83
4/30/05......4.75..........4.78..........4.73
5/07/05......6.74..........6.55..........6.94
5/16/05......6.94..........6.52..........7.37

    Bookmark   May 18, 2005 at 10:22PM
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jimster(z7a MA)

    Bookmark   May 18, 2005 at 10:42PM
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jimster(z7a MA)

"Suprised there hasn't been an organic/chemical foliar comparison, such as compost tea vs commercial foliar plant food."

Good idea. Want to do it?

Jim

    Bookmark   May 18, 2005 at 10:46PM
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jimster(z7a MA)

Here is a scan of a leaf from the same position on each of the ten experimental plants. Five of the plants received foliar feeding. Five did not. They are in random order. Can you determine visually which are which? Scrutinize color, size, etc.

    Bookmark   May 23, 2005 at 1:48PM
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gailnewgarden(Z8FL)

just for fun:
No - 1, 4, 7, 9 and possibly 6?
Yes - 2, 3, 5, 8, and 10
Gail

    Bookmark   May 23, 2005 at 2:31PM
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bushpoet(z6 Bronx NY)

yes: 2, 3, 5, 6 & 8?

~bushpoet

    Bookmark   May 23, 2005 at 4:22PM
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duderubble(z5 Illinois)

2,3,5,6 & 8 are healthiest.

    Bookmark   May 23, 2005 at 5:48PM
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jimster(z7a MA)

Here is one which was posted on the Growing Tomatoes site:

* Posted by: Steve1805 TX (My Page) on Mon, May 23, 05 at 16:07

I'm by no means an expert but from a general observation 3, 5, 6, and 8 look the healthiest.

    Bookmark   May 23, 2005 at 6:44PM
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Gardenmama1(z8/SE Virginia)

From what I can see, 2,3,5,6,8 look the healthiest and greenest
-Martha

    Bookmark   May 23, 2005 at 6:51PM
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BrokenAppleTree(z6 OH)

I'm going with 2,3,5,6,8

ok, didn't read anyone elses until just now, looks like we all think the same ;-)

- Brian

    Bookmark   May 23, 2005 at 9:15PM
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Phaethon(Zone 8)

I 'd say 2,3,5,6,8 and 10 look to be the most vigorous.

Nik.

    Bookmark   May 24, 2005 at 2:31AM
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jimster(z7a MA)

The concensus of those who evaluated leaf samples was that leaves from plants 2, 3, 5, 6 and 8 appeared most "healthy" or most "vigorous". This corresponds with the plants which received foliar feeding. The height difference between groups N and Y also became more distinct as the experiment proceeded. It can be reasonably concluded that plants can benefit from dissolved nutrients applied to their leaves.

This answers the question posed at the start of the experiment, "Can leaves absorb water and nutrients well enough to benefit a plant? " Apparently, they can.

While it was not the intention of the experiment to determine the effectiveness of foliar feeding, the best method of applying it or other variables, a couple of observations can be made. First, the differences observed were slight, and were not observable until the third or fourth week. Second, the effects of foliar feeding were observable, for the most part, on portions of the plants which developed during the experiment. Lower portions of the plants, which had developed prior to the start of foliar feeding were less affected or not affected at all.

During the course of the experiment, some changes were made. These changes were intended to make the result, if any, more readily observable.

In week 2, a change was made in the procedure in order to give the foliage more time in the wet condition and, therefor, more opportunity to absorb nutrients.

At the suggestion of Jkirk,, and after a brief literature search to explore the principle involved, a small amount of epsom salt (magnesium sulfate) was added to the nutrient solution at the start of week 3. Because differences between the two groups began to appear subsequent to that change, it is tempting to attribute the changes to the epsom salt. We cannot be certain, however, because the variables associated with the foliar fed group included both epsom salt and soluble fertilizer. A follow-up experiment to evaluate the effectiveness of epsom salt would be interesting.

Jim

    Bookmark   May 24, 2005 at 9:57PM
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LandArc(z9 CA)

Jim,

If you look into epsom salts used as a fertilizer, you will see that the addition of the epsom salts modifies that balance of chemicals (and thus nutrients) being applied. It is a proven contributor to some gardens. Great experiment and results. I foliar feed as we found that it could be useful in pushing plants along towards growing faster.

Bob

    Bookmark   May 24, 2005 at 11:48PM
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RuthieG__TX(z8 TX)

Wow very interesting...thanks so much for sharing all of that info...

    Bookmark   May 25, 2005 at 5:36PM
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ddsack

I have been waiting for the results of your experiment with great anticipation ... thanks for all your work! I'm one that has been skeptical about the benefits of foliar feeding -- my gut feeling has always been that it makes about as much sense as smearing mashed potatoes and gravey on my arm. (Yeah, yeah, I know about various skin patches for drugs, but still ...)

But I have to admit, that based on your photos, it does definitely seem to make a difference.

Having said that though, I still have to wonder about any added benefits if a person is already fertilizing with solution absorbed by the roots. I notice you were very careful to not allow your foliar spray to enter the root system in the pots. I would imagine that the added growth in the foliar fed plants might be mostly attributed to the fact that the untreated plants had used up the available nutrients in their pots by the later weeks, so only the treated plants were able to extend their growing time due to the foliar supplements. This would seem to be a good thing to know, for those of us that need to hold plants in their pots a little longer than is desirable due to weather etc.

Your experiment brings up more questions. Is there a speed limit to a plants ability to grow? Can you over-fertilize by using both foliar and root fertilizers? At what point are you just wasting your time and money, and at what point are you are actually harming the plant?

Good thing tomatoes are such forgiving plants, fuss with them or leave them alone, you can still expect a few tomatoes at the end of the season. Thanks again!

    Bookmark   May 26, 2005 at 12:46PM
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jimster(z7a MA)

You know, I've also wondered about smearing medications on the skin to relieve muscle pain. But at least some compounds do penetrate the skin. Your example of patches shows that. I know even less about how skin is penetrated by chemicals than how it works with leaves.

Hmm... Do you think patches would work on tomato plants? :-)

Jim

    Bookmark   May 26, 2005 at 2:19PM
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atillathepun(Sunset Z15 CA)

hmmm, plant patches...the trick would have to be to see if stalks absorb like leaves do, since you wouldn't want to interfere with photosynthesis. Also, they would have to be a difficult combination of potency and slooooooow release in order for them to be efficatious. Probably too much effort/too little result.

    Bookmark   May 26, 2005 at 5:56PM
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marie_in_wa(8 (coastal))

I watched this thread with interest last year, and I'm curious - if you grew them out, did you keep tabs of which was which through the growing season? If so, which produced the best?

    Bookmark   April 22, 2006 at 11:05AM
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treponema

I've been foliar feeding 6 tomatoes with a very dilute solution containing Iron, Boron, Zinc, Manganese, Magnesium and Copper.I lowered the pH to keep the iron from precipitating, and added a few drops of Tween (a wetting agent.) Been doing it for about 1 1/2 months. This is definitely not a controlled experiment but the plants look great. Maybe like chicken soup - it couldn't hurt.

    Bookmark   May 26, 2006 at 6:27PM
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vodreaux(SoCal)

Here is some more information on Foliar Feeding.

FOLIAR APPLIED PLANT NUTRIENTS

FOLIAR FEEDING -
Foliar feeding, using natural organic foliar fertilizer, is an effective method for correcting soil deficiencies and overcoming the soilÂs inability to transfer nutrients to the plant. Tests have shown that up to 90 percent of a foliar fed nutrient solution can be found in the smallest root of a plant within 60 minutes of application. A project conducted at Michigan State University, using radio­active tagged nutrients, proved that foliar feeding can be 8 to10 times more effective than soil feeding.

The effectiveness of foliar applied nutrients is determined by (1) The condition of the leaf surface, in particular the waxy cuticle. The cuticle is only partially permeable to water and dissolved nutrients and, as a result, it can limit nutrient uptake. (2) The length of time the nutrient remains dissolved in the solution on the leaf's surface. (3) diffusion, the movement of elements from a high concentration to a low concentration. For diffusion to occur, the nutrient must dissolve. and (4) The type of formulation. Water-soluble formulations generally work better for foliar applications as they are more easily absorbed when compared to insoluble solutions. Water insoluble formulations are generally slow acting because they must dissolve before they can be absorbed and are more applicable for soil applications.

TIMING
The best time to foliar feed is late evening to early morning. These are the times when the stomata (the small opening on the leaves) are open.

Avoid foliar spraying when Â
 When the temperature above 80F.
 When the weather is hot and dry and water vapor is leaving the cells.

Foliar spray Â
When the temperature is 72F or below.
 Early in the morning when the cells of the leaf are full of water and dew has collected on the foliage.
 When air temperatures and humidity both equal 135 or less.
 When air temperature is cooler than soil surface temperature.

NOTE: A biological surfactant can reduce water tension and improve the absorption rate of foliar sprays.

Where possible, the pH of a foliar spray should be between 6.2 to 7.0. To promote young plant growth a sweeter (alkaline) solution (pH 7.0) is recommended. For established growth, a more sour (acid) solution (pH 6.2) is recommended.

An effective foliar application can produce results in 1 to 6 days. Use a refractometer to detect results.

Here is a link that might be useful: FOLIAR APPLIED PLANT NUTRIENTS

    Bookmark   June 5, 2006 at 1:09AM
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jimster(z7a MA)

Marie,
Sorry for being so slow to respond. I've been away from this forum for a while.

I grew out only one of the plants used in the experiment and gave the others away, so I have no data on how they did later.

In any case, as you could see from the results, the differences between plants were slight. Not an exciting result but, hey, we wanted to know the truth, didn't we.

treponema,
Most of the time, we don't have clear data. We have to go rely on our best hunches. Go for it.

vodreaus,
You have to be a little skeptical about statements used in promoting a product. I read the original sources for some of that blurb and did not find it as conclusive as it sounds when cited selectively. Most products produce some results when used as directed, but few, if any, are miraculous.

Jim

    Bookmark   June 10, 2006 at 6:10PM
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dilbert(z5 IL)

"one gallon of each. Solution A is distilled water with five drops of liquid detergent as a wetting agent."

I know from experience that, at least, 0.5 tsp/gal of surfactant are needed for thorough coverage. You need to use a nonionic surfactant. Household detergents are partially ionic and often contain chelating agents which bond with some ions, particularly Ca+2 and Mg+2. There are surfactants made for foliar sprays, e.g., see http://rosecare1.stores.yahoo.net/adjuvants.html.

The silicone based surfactants, Kinetic and Silwet L77, are reputed to be the best for tranferring other solutes into the plant, but, I worry about biodegradability within the plant. Although I haven't tried it, N-90 was recommended to me. Personally, I have had good success with Triton X-100, which is NOT registered for horticultural use.

It may interested you to know that urea has biological effects on plants that are not related to its nutritional value. It is well known that urea penetrates leaf surfaces faster than most other substances. I have been told that it causes leaf stomata to open. I have personally observed that a large dose of urea temporarily stops a plant from growing but, after 1-2 weeks, there is a sudden burst of growth and the plant more than catches up with the controls.

"The most widely agreed upon benefit of foliar feeding is that nutrients can more quickly reach all parts of the plant than by root feeding."

Maybe, NPK, but not some other elements such as boron. Foliar fed B never reaches roots. Also, it may interest you to know that some growth regulators such as ancymidol are almost completely ineffective as sprays.

    Bookmark   July 1, 2006 at 12:06PM
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jimster(z7a MA)

Thanks for the interesting information. If I were to carry this further and attempt to optimize a foliar plant food, that sort of knowledge would be very useful. As it was, my only goal was to find out, through first hand observation, if plants can absorb nutrients through their leaves.

Jim

    Bookmark   July 10, 2006 at 12:20PM
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digdirt2(6b-7a No.Cent. AR HZ8 Sun-35)

bump - Now that I found this it's too good to lose Jim. :)

    Bookmark   June 12, 2007 at 7:17PM
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billtex(8atx)

JIMSTER, I really like your experiment, because you kept it simple. IF IT IS TOO SCIENTFIC IT WOULD BE WORTHLESS BECUSE MOST GARDENERS WOULD OPT. TO BE SIMPLE AS POSSIBLE FOR THEIR GARDENING. BILL

    Bookmark   June 13, 2007 at 7:48AM
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jimster(z7a MA)

Hey, it's still here.

Maybe it's time for another experiment. I'm thinking.

Jim

    Bookmark   June 7, 2008 at 8:32PM
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protea_king(Western Cape)

Hi Jim, I read somewhere that tomatoes don't like water on their foliage, which is why its recommended that you water from below not overhead. Did you notice any adverse effects of the application of water onto the foliage of your tomatoes in your experiment?

    Bookmark   August 30, 2008 at 3:58PM
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iamgrowerman

Foliar feeding works wonders if you do it right.

The reason plants don't like water on their leaves is the way light refracts through droplets of water. Basically each drop of water acts like a magnifying glass, concentrating the sun's rays onto a small spot of the plant's leaves, burning them.

This is why surfactants are so important to foliar feeding. They break the surface tension of water so that it won't form droplets and instead spreads smoothly over the surface of whatever it's on. Soap is a good example of a surfactant.

IMHO you want to use something a little more purpose-built for the task than soap if it's for a plant you eat. I wouldn't want to put soap on my salad so I won't spray it on my plants either. I've heard really good things about Organic Wet Betty. Advanced Nutrients makes it and it's all organic to boot.

    Bookmark   March 22, 2009 at 10:38AM
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cyrus_gardner(8)

Great experiment GIMSTER

I have a few observation, regarding actual foliar feeding and your experimental method.
1- In actual foliar feeding, inevitably part of the sprayed on nutrients fall on the soil and eventually get into the root system. That is to say that in reality and practice there can be no pure foliar feeding.

Experiment of Pure foliar feeding can make better sense if it is compared to no feeding at all. This way it can more clearly determine the effectiveness of foliar absorption.

2- If I had the opportunity, would run a similar experiment,
adding a third and fourth groups:

Third group will get no feeding, just watere.
Fourth group will allow the nutrient fall of the leaves onto the soil. This is fair as long as the amount of nutient soution fed is equal to that of root-fed group.
For the gardener or farmer the end result is what it counts.And in the real world there can be no pure foliar feeding.

Final Note:
I have heard alot about foliar feed with epson salt. I have heard those who swear by it. This year I am going to conduct my own semi-scientific experiment in my garden lab.
I am going to do it on peppers and tomatoes.

Another point to consider, about any feeding, is the productivity. Greener tomato or pepper bush may not mean more productivity. But it may have some value for the vegetables which ther greens are consumed.

    Bookmark   March 27, 2009 at 5:47AM
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knowboddy

One thing you might want to consider in your foliar fertilizer experiment is the addition of something like Wet Betty by Advanced Nutrients.

It's specially designed for this kind of thing. According to the label it combines surfactants and a bunch of other stuff to promote growth. Seems like it would be a good foliar fertilizer to compare with the other known benchmarks.

    Bookmark   April 28, 2009 at 3:45PM
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struwwelpeter(5)

In my experience, the best surfactant is Triton X-100. Usually, 1/2 tsp/gal is sufficient to prevent beading on glossy leaf surfaces.

http://en.wikipedia.org/wiki/Triton_X-100

sold relatively cheap at:

http://apps.webcreate.com/ecom/catalog/product_specific.cfm?ClientID=15&ProductID=17342

    Bookmark   June 12, 2009 at 12:15PM
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albert_135(Sunset 2 or 3)

Below is a link to some serious, howbeit readable, material on foliar feeding.

Here is a link that might be useful: foliar feeding

    Bookmark   November 6, 2011 at 12:00PM
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KatyaKatya(6)

Very interesting, so comprehensive, thread continued over several years...
I found that the benefits of foliar feeding where I live are outweighed by the wet climate. The less moisture on leaves here, the better, regardless. It encourages mold and rot, even with good air circulation.

    Bookmark   January 27, 2012 at 10:31PM
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jimster(z7a MA)

Here is a post from the Vegetable Growing Forum:

Posted by Edymnion z7 (My Page) on Mon, Dec 31, 12 at 16:06

Hey Jim, I have a question about your foliar feeding experiment.
I read where you were careful not to let the foliar feed drip into the soil, but (and maybe I just overlooked it), I don't see anywhere that you said you were giving the non-foliar plants the same additional food through the roots?

From my experience, the question isn't "Can plants absorb water and nutrients through the leaves", but "Is foliar feeding more effective than simply pouring it directly into the soil?"

I mean, if both sets of plants are treated the same otherwise, and one is getting additional feeding, it seems rather straight forward that it would do better. The real question is efficiency. If both plants receive the same amount of feeding, only one gets it only on the leaves and the other gets it only on the roots, which one will do better?

    Bookmark   January 1, 2013 at 11:43AM
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jimster(z7a MA)

"I read where you were careful not to let the foliar feed drip into the soil, but (and maybe I just overlooked it), I don't see anywhere that you said you were giving the non-foliar plants the same additional food through the roots?"

I am embarrassed to discover that I neglected to include that information in my report. Not that it would have affected the results but, for the sake of completeness, it should have been included.

I do not remember if I provided any nutrition to the roots beyond what was in the seed starting mix; ProMix BX. My normal practice with seedlings is to start giving them a weak solution of fish emulsion when they have two sets of true leaves. This is what I would have done if I provided any root feeding and I would have done it to both groups. However, I suspect that the only feeding I gave in this experiment was to the foliar fed group.

"From my experience, the question isn't "Can plants absorb water and nutrients through the leaves", but "Is foliar feeding more effective than simply pouring it directly into the soil?"

That is one of several questions posed by readers. But, as you correctly understood, the one and only question I was attempting to settle was whether plants can absorb useful amounts of soluble nutrients through their leaves.

Once again, I encourage other gardeners to undertake experiments to satisfy their curiosity about various gardening topics. I assure you it's a fun, inexpensive and satisfying activity.

Jim

    Bookmark   January 1, 2013 at 12:17PM
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growneat

Bump.

This thread is so good I thought I would bring it back for another go around. Marv

    Bookmark   September 6, 2013 at 1:05PM
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