using eggshells

katkni(4)March 11, 2012

We shut down the compost for the winter, but I continued to save eggshells. What I did was crush them into a gallon sized plastic bag in the freezer. It's about half full now.

What's the best way to use these? I plan on starting tomatoes soon, and transplanting into pots once before planting outside. Should I make a "tea" and water the seedlings? Or crush directly into the pots when I transplant?

Last year I lost the first 2 tomatoes to blossom end rot, and I panicked! Luckily that was the last of the loss, but now I am feeling a little paranoid. Are eggshells (even a quarts worth) really enough calcium to prevent this problem?

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digdirt2(6b-7a No.Cent. AR HZ8 Sun-35)

Are eggshells (even a quarts worth) really enough calcium to prevent this problem?

No. The causes of BER and the use of egg shells aren't even related. It is an old wives tale.

The use of egg shells, or pointlessness thereof, is often discussed here and I linked one from last week for you below. The search will pull up others if interested. Also search BER for information on its actual causes and effective methods of prevention.


Here is a link that might be useful: Using eggshells

    Bookmark   March 11, 2012 at 6:22PM
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Whoops! I didn't look far enough into the FAQs. Thanks.

    Bookmark   March 11, 2012 at 6:23PM
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DWD2(10a, Sunset 17)

katkni, BER is caused by a calcium deficiency. Perhaps this review will help everyone's understanding.
To be sure, exactly how BER can appear in tomatoes seems to be driven by several potential mechanisms that prevent adequate calcium from getting to involved fruit. I will point out that one of the most successful tomato growers I am aware of uses egg shells. Possibly this link will give you some tips. Ms. Sandburg is the exclusive gardner for one of the most acclaimed restaurants in the US, Manresa. It is not a hobby. It is her livelihood.

Here is a link that might be useful: growing tomatoes in containers

    Bookmark   March 13, 2012 at 6:29AM
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digdirt2(6b-7a No.Cent. AR HZ8 Sun-35)

katkni, BER is caused by a calcium deficiency

A close reading of the article linked above makes it very clear that calcium deficiency is NOT the cause of BER. It states it in no uncertain terms. Clearly then, as many other tests and publications have documented, adding supplemental calcium to soil that already contains sufficient calcium serves no purpose.

Add to that the well documented fact that egg shells take several years to break down in the soil and that the resulting calcium they may deposit is still not in a form usable by the plants, it is clear that they provide no benefit to the plants.

The only purpose they serve is to make the gardener, regardless of who they are or what restaurant they grow for, feel better because then they can claim "eggshells prevented/cured my BER" when in fact there was no correlation whatsoever.


    Bookmark   March 14, 2012 at 2:49PM
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No disrespect, but it sounds like Ms. Sandburg succumbed to the false advertising about eggshells in tomato holes. She might as well have put a handful of lemon seeds in the hole and come out with the same results. Digdirt knows what he's talking about in this case.

    Bookmark   March 14, 2012 at 3:32PM
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DWD2(10a, Sunset 17)

digdirt, I do not know if you actually read the article, but in no uncertain terms, if you did read it, you did NOT understand it. I direct you to the beginning of the final paragraph where the authors state,
"In a horticultural context, BER can be considered simply
as a symptom of Ca deficiency in the distal fruit tissue
during rapid cell expansion. Thus, BER in a tomato crop
can be minimized by spraying Ca onto young tomato fruit
(Fig. 5; Wilcox et al., 1973; Ho, 1998a; Schmitz-Eiberger
et al., 2002). In the glasshouse, this treatment prevents BER
more effectively than other current horticultural practices,
such as the manipulation of the mineral composition of the
feed (e.g. lower N supply) or the growth environment
(e.g. lower canopy transpiration), because it increases the
Ca concentration of distal fruit tissues directly. However,
this treatment can only be effective when regular Ca sprays
are targeted to young fruit before any symptom of BER is

Could they be any clearer? BER is caused by calcium deficiency in the distal fruit tissues of tomatoes. This is an entirely settled scientific FACT as far as I can see from ALL the articles I have read. As I mentioned above, there are several mechanisms discussed in this review that can lead to a calcium deficiency in the distal fruit tissue. That deficiency need not be caused by a low level of Ca in the growth media. If you can point us to an article in a peer reviewed scientific journal demonstrating the contrary, I would love to see it. I think one thing worth considering is there may be certain growth conditions where egg shells are helpful in reducing/eliminating BER and some sets of conditions where egg shells are less helpful or ineffective.

garystpaul, I might suggest you read the review I supplied and reassess Digdirt's understanding in this particular case. As a suggestion, should you want to REALLY treat yourself, take a trip to Los Gatos, CA to Manresa restaurant during one of their tomato feasts in August or September. All the produce at Manresa is grown by Ms. Sandburg & my bet is those tomatoes will give you a high level of respect for her methods.

Good luck with your gardens!

    Bookmark   March 14, 2012 at 6:04PM
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digdirt2(6b-7a No.Cent. AR HZ8 Sun-35)

Yes I did read it and have read it before and it has been discussed here in great detail in the past as well along with all the articles referenced by the author of this particular study. In other words, this is not a new debate by any means.

The point is calcium deficiency in the distal fruit tissues - a well establish fact - NOT in the soil which is what we are discussing here. That is where the eggshells are added after all. The primary contributing factor is a circulatory issue within the plant itself and adding eggshells to the planting hole (or TUMS or milk or any other concoction) has no effect on the circulatory system within the plant.

We are discussing the use of eggshells here after all and your reference to Ms. Sandburg's use of eggshells indicates she and you consider it a cure for BER. If that were actually the case then the commercial industry could spend the millions of dollars they currently spend annually on BER research on buying chicken egg farms instead.

Thousands of home gardeners grow for restaurants annually but that in no way makes our particular method of growing them universal. Claiming so is just a common fallacy of logic.

Now if you can find a way to directly inject eggshell suspension along with the beneficial bacteria needed to convert it to usable nutrients into the distal tissues of the fruit it might be relevant. But as studies on the common sprays show "foliar applications of calcium are of questionable value according to research because of poor absorption and movement to fruit where it is needed..."


    Bookmark   March 14, 2012 at 8:08PM
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DWD2(10a, Sunset 17)

digdirt, Would you mind directing me towards those discussions of scientific articles on BER on this forum? I have looked through a LOT of threads and never seen more than 2 articles, more often one and typically none, discussed. I will be pleasantly surprised if your claim is true. If it is true, I will owe you a sincere apology.

In point of fact, soil deficiencies in calcium were first demonstrated to cause BER in a classic paper by Evans & Troxler in 1953 in the Proceedings of the American Society of Horticultural Science volume 61, pages 346-357. As I said in my post above, "BER is caused by a calcium deficiency." I did not say where. I further said, "To be sure, exactly how BER can appear in tomatoes seems to be driven by several potential mechanisms that prevent adequate calcium from getting to involved fruit." Is a Ca deficiency in the soil or potting media the ONLY cause of BER? As I indicate, the answer is no. Is it one way you can get BER? Every study I am aware of says yes. Your statement that adding anything to a growing media that will impact the concentration of minerals available to a plant "has no effect on the circulatory system within the plant" is just silly. The impact may be minor, but there will be one.

I do not know if the use of egg shells a cure (preventative really) for BER. My feeling is the egg shells may be a useful part of the regime I use to grow tomatoes. Neither I nor anyone that I have direct knowledge of their results has encountered BER in their tomato growing using this regime. Are egg shells responsible in part or completely for that result? I do not know and I do not have the time to test it in any meaningful way. I spend my professional time in science in pursuit of other goals. I very strongly doubt that the commercial tomato (or pepper or eggplant) industry directs meaningful funds to current academic BER research. The funding resources I notice referenced are competitive, governmental sources, for instance see the "Acknowledgements" at the end of the review I referenced above. There may be an exception or 2, but "millions of dollars" annually? To be fair, this is not my area of research and there could be funding sources I don't pay attention to. When you make claims like this, it would be helpful if you could please provide a link to the published source so we can all make our own decisions as to whether it is a reliable source.

I agree with you that there is no universal way of growing tomatoes. There are lots of different paths that give you fine fruit. I have no way of knowing how many "home gardeners" provide produce to restaurants. The point I am trying to make is that Ms. Sandburg depends on the products she produces at Love Apple Farms (love apple is an old nickname for tomato) for her living as well as several of her employees. She grows exclusively for one of the most acclaimed restaurants in the world. If either the quality or the quantity of her products were not world-class, chef Kinch from Manresa would go elsewhere in an instant. There appears to be no shortage of extraordinary growers in Northern California competing for high-end restaurants as customers if one is to believe the Food column in the San Francisco Chronicle. I do not think it a fallacy of logic to believe that affords her and her methods considerable credibility.

The regime I use puts a handful of crushed egg shells in the planting hole. I also add a preparation of mycorrhiza fungi and rhizobacteria. At the end of the season last Fall when I removed my plants from their pots I dissected several of the root balls. What I observed was the egg shells were engulfed in root. When I pulled the root away and examined the shells, they were very different than when they were placed in the planting hole. The egg shells now had no stiffness and seemed lighter. I got some egg shell pieces as close to the same size as I could that were in the bag these came from for the planting. Upon weighing, it appeared >90% of the egg shell weight had been lost. I dissolved the 2 sets of egg shells in phosphoric acid to solubilize the calcium carbonate and used a colormetric test titrating with EDTA to quantitate the calcium. The egg shells that were removed from the plant roots had calcium just at the low limit of detection. The egg shells that had not been with a tomato plant had at least 1000 fold more calcium. It was a quick & dirty test to be sure. My working hypothesis is the calcium from those eggs ended-up in the plant. Your final statement/quote strikes me as odd. You quote some source that you want readers to presume is authoritative, but provide no source reference so anyone else can go read for themselves. It is directly at odds with a statement by the scientists writing the review. They provided scientific references to validate their statement about foliar application of calcium preventing BER. They even show a figure from the 1998 Ho paper demonstrating the reduction of BER with a calcium spray. In the paper by M. Schmitz-Eiberger et al, they induce BER by dropping the Ca level in their soilless culture from 2.9 mmol/L to 0.29 mmol/L and then show a positive benefit to foliar application of CaCl2.

To end it, do egg shells impact BER under the conditions I use them? I do not know. Does using them negatively impact my tomatoes? I have observed no evidence of that and have seen no publications demonstrating that. So, from my point of view, the egg shells do not appear to hurt and could well be helping. I choose to use them. Others can choose not to use them. I do not believe dogmatic statements about the "pointlessness" of using egg shells is constructive.

    Bookmark   March 15, 2012 at 5:57AM
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This is fascinating!

Thanks to everyone for the information. At the very least, I am not going to count on these eggshells from preventing BER. One way or another, they will end up in my garden.

Digdirt's link mentioned eggshells as a physical barrier against slugs. Any thoughts on this? Or maybe I'll go start a new topic ;)

    Bookmark   March 17, 2012 at 10:55AM
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Crushed eggshells are a decent barrier against slugs; they don't like crawling over gritty substances. Diatomaceous earth is another good one.

Every eggshell, along with most other vegetal kitchen waste I have, ends up in my compost heap, where I assume it will break down over time and work to the benefit of plants.

I, too, have been fascinated by this thread. Like DWD2, whose passion I admire, I'm a foodie and pay attention to what folks have to say about growing for the kitchen. For other reasons, I also like to speculate, in cases where it's not obvious, on the gender on the writer.

    Bookmark   March 17, 2012 at 2:25PM
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As the egg shells in the soil decompose the calcium should be released into the soil. And while nutrients in the soil alone do not help the plant; once the roots absorb the nutrition then it can help. We do not have a reasonable way to inject the calcium directly into the plant but we don't need one; that is what roots are for.

Also there was an experiment to see if egg shells worked in preventing slugs.

Complete with pictures, they show that slugs are not deterred by egg shells.

Here is a link that might be useful: What is blossom-end rot? How can I prevent it?

    Bookmark   May 24, 2014 at 12:19PM
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carolyn137(z4/5 NY)

I've spent many years following the information about BER and updating when necessary and consulting with many University and other sources in the past.

I tried cutting and pasting my recent update at idig but couldn't do it, so please read post, I think #27, or near to that, short term memory here, LOL, and I do think it's worthwhile considering some of the comments that have been made above.



Here is a link that might be useful: BER

    Bookmark   May 24, 2014 at 2:38PM
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digdirt2(6b-7a No.Cent. AR HZ8 Sun-35)

Here's your post Carolyn

Blossom End Rot (BER) is one of the most common tomato problems seen in the early part of the season. It is a physiological condition, not a disease caused by a fungus or a bacterium or a virus. Therefore it cannot be treated.

And as I'll explain below, it is very difficult, if not impossible, to
prevent. BER has nothing to do with the blossoms, it refers to the fact that at the end of the tomato opposite the place where the tomato is attached to the stem, called the stem end, is the bottom of the tomato, which is called the blossom end. You often can see remnants of the blossom attached to that end as the tomato forms. At the blossom end one sees a flattened area that looks
leathery and initially brown and then black, as the fruit rots.

BER is said to occur when there is uneven watering, drought, heavy rainfall, excessive nitrogen fertilization, rapid plant growth or root pruning during cultivation, high winds and rapid temperature changes. So lots of conditions have been associated with BER. But the rapid plant growth and nitrogen fertilization are both common to conditions seen early in the season, and indeed, that is when most BER occurs. Then it usually just goes away.

BER occurs because under the conditions just stated, Ca++ moves from the fruit into the vasculature (stems) of the plant. Or, some feel that Ca++ never reaches the fruits becasue under stress demand for Ca++ exceeds supply.This lowered amount of Ca++ is what causes BER. Excessive rates of transpiration (kind of like sweating in humans) also is involved in Ca++ displacement. Thus, the plant as a whole is NOT Ca++ deficient, the Ca++ has just been displaced.

It has been shown that plants that have normal Ca++ levels in the stems can have BER fruits, so the problem is not one of lack of uptake from Ca++ in the soil.

Many books and magazine articles tell you that by adding Ca++ in the form of lime or eggshells, for instance, that you can prevent BER. That does NOT appear to be true. It was several years ago that I found out that University field trial experiments have so far failed to show that BER can be prevented by addition
of Ca++. I recently e-mailed my friend at Cornell who told me all this two years ago, to again confirm that it was still true, and will update you, if necessary. Peppers and many cole crops are also susceptible to BER and there's quite a bit of literature on BER and Ca++ for those crops also. The results are the same; addition of Ca++ does not prevent BER.

Some data strongly suggests that foliar spraying with Ca++ is of no use because not enough gets to the fruits to do any good. And it's known that the sprays for fruits that are sold are useless. No molecules can get across the fruit epidermis. If they did, just what do you think would happen to the fruits when it rained.LOL

However, use of Ca++ sprays on small still green fruits, again, has been shown by some, not many, to help since the epidermis of those small fruits is more permeable,

Not all varieties of tomatoes get BER. Some never do, others are horrible. That's not surprising since certainly there are slight physiological differences between varieties. After all, almost all garden tomatoes, with the exception of the currant tomatoes are in the same genus and species, Solanum lycopersicum. And we humans are all in the same species, Homo sapiens, var. sapiens...and look how different some of our physiologies are.

So, BER is a physiological condition, cannot be cured, and current
literature data suggests it cannot be prevented. It occurs on some, but not all varieties of tomatoes, is usually seen early in the season and then stops, for most folks. It would be nice to say that you could even out your watering, prevent droughts and heavy rainfalls, ensure even and not rapid growth of plants and not disturb the roots by shallow cultivating. But on a practical basis, I think we all know that's almost impossible. So, BER has never bothered me, I just ignore it, and it goes away with time.

Adding Ca++ to soils that are Ca++ deficient makes sense, but few soils are. And if soils are acidic, Ca++ is not taken up well but addition of Epsom Salts to the soil can aid in Ca++ uptake in such acidic soils.

Many folks add Ca++ and then see that BER disappears. What they fail to realize is that BER is going to go away anyway, as the season progresses. And that's because as the plants get larger they are better able to handle the many stresses that can induce it. So one cannot correlate addition of Ca++ to disappearance of BER. Universities have done so many stidies on this already
because BER is a billion dollar problem in the commercial veggie industry.

Of all the stresses that can induce BER the two that are most under control of the home gardener are fertilization and water delivery.

That is, too much fertilizer causes plants to grow too rapidly and is perhaps one of the major causes of BER developing. Too rich soils do the same thing. Plant growth simply outstrips the ability of Ca++ to get to the fruits.

Mulching to help ensure even delivery of water also can be done and is also one of the two major causes, IMHO, of BER.

BER appears usually on half ripe fruits but also can appear on grass green ones.Lack of Ca++ only occurs at the blossom end of the fruit and it causes tissue destruction which leads to that papery greyish/blackish lesion appearing.Now sometimes that lesion opens up and fungi and bacteria enter and that causes the rotting and also the appearance of fungal growth on and in the lesion.

Sometimes one can see what's called internal BER and that's seen when you cut open a tomato and the insides are black but there are no external symptoms of BER.

Just pick off any BER fruits that appear and soon the next fruits to ripen will BERless.

Many books, magazine articles and websites still say to add Ca++ as lime, eggshells, etc, and seem not to be aware of all the research that has been done in the last 30 years. But many books, magazine articles, are now sharing this newer information about addition of Ca++ not being able to either prevent or cure BER except in rare situations of low Ca++ soils or acidic soils.

I suppose it will take another generation for the right information to be present everywhere. And from my own experience i can tell you that there will be folks who will get madder than can be when they read this kind of info because they simply believe otherwise. So be it. Addition of modest amounts of Ca++ aren' t harmful, but I feel strongly that folks should know what's going on with past and current research re BER and Ca++.


Hope the above helps.



    Bookmark   May 24, 2014 at 3:26PM
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carolyn137(z4/5 NY)

Thanks so much Dave b/c when I tried and tried to cut and paste it it wouldn't work at all bc adjacent areas were highlighted, but the software there is not the same as here, so now I'm going to try and cut and paste it from here to put in my faves. ( smile)


    Bookmark   May 24, 2014 at 3:45PM
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