Nutritional/micronutrient supplements

avalon2007February 24, 2014

Hi rose folk,

Question for you: What are your experiences with micronutrient supplements?

The following post is NOT an ad for any supplement, even though when I re-read it it, it did sound like an advert.
Sorry about that...I'm just really excited because I've never had much success growing roses before.

I am absolutely astounded at the change in my roses- they now look as if they are going to live! They're covered with strong, new growth, loads of buds, and dark green, healthy foliage. They've never looked so good, and I just had to tell everyone!

Fertilizer with micronutrients just wasn't doing the job- it seemed like it even made matters worse. I swear that I killed a couple of my roses with fertilizers, even though I didn't over-fert them. They would get a spurt of new growth that was weak, small and pale, and then start to go downhill.

The micronutrient supplement I'm using doesn't have phosphorous or potash, and only 1% nitrogen. The sand here has a great deal of phosphorous, and I'm wondering if that was the problem with using regular fertilizer- too much phosphorous. I only use the supplement and compost now to feed the roses, and they are doing so well.

Feedback and comments on my "garden miracle" would be appreciated- I'm really curious to see if anyone else has gotten the same results without using any fertilizer.



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tapla (mid-MI z5b-6a)

..... not a regular contributor to this forum, but I saw the post on "most recent posts" and thought I'd comment. I've tried to set a goal for supplementing the nutritional needs of plants in containers. I'll start there and invite anyone that might care to, to improve upon the goal:

The goal for fertilizing containerized plants can easily be described. You should work toward ensuring that all the nutrients plants normally secure from the soil are in the soil solution at all times, in the ratio at which the plant actually uses the nutrients, and at a concentration high enough to ensure no deficiencies yet low enough to ensure the plant isn't impeded in its ability to take up water and the nutrients dissolved in water. This goal is easily achievable using one water soluble synthetic fertilizer. You CAN use organic forms of nutrition, like fish/seaweed emulsions or various types of meal, but that makes it much more difficult to achieve the goal.

Growing in the ground is different. Most container soils break down so slowly that the grower can move forward with the idea that the medium isn't going to play a major role in satisfying nutritional needs. When growing in the earth, many nutrients are going to be available in adequate volume in the form of salts that occur after microorganisms break nutrients down into elemental forms the plants can assimilate, and some nutrients will likely be deficient. The goal of working toward ensuring that all the nutrients plants normally secure from the soil are in the soil solution at all times, in the ratio at which the plant actually uses the nutrients, and at a concentration high enough to ensure no deficiencies yet low enough to ensure the plant isn't impeded in its ability to take up water and the nutrients dissolved in water still applies, though. The problem is, if you don't know what nutrients are missing or available in excess, there is no hope of optimizing nutrition ....... unless you have your soil tested. I can say this with confidence because an excess of any one or more nutrients has the same potential to limit growth as a deficiency of same, so both are to be avoided to the greatest degree possible.

When we apply fertilizers w/o knowing what the plant needs, we can easily get the ratio of nutrients in the soil solution well out of the favorable range, which causes complications. So, micronutrients when the plant is deficient in what you are supplying are a beautiful thing, but the micronutrients (or macronutrients) that you're creating an excess of by fertilizing when the supply is in the adequate to luxury range, has only the capacity to limit.

Keep in mind too, that micronutrient deficiencies are often caused by soil pH. It may be that there is an adequate amount of an element in the soil, but it is bound to other elements (making it insoluble and unavailable for uptake) because of a pH that's unfavorable. A soil test will also address the pH issue.


    Bookmark   February 24, 2014 at 1:42PM
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nikthegreek(9b/10a E of Athens, Greece)

Al, you describe my exact thinking. Growing in a pot is very close to hydroponics where you have to supply all the nutrients plus you cannot depend on biological processes supplying them. For plants in the ground I believe the issue is more or less as you describe. One thing to point out is nutrient interdependencies and synergistic / antagonistic relationships.

Avalon, in commercial production deficient micronutrients are often supplied by foliar applications. This ensures faster and better absorption of most micronutrients (and macros like Mg) without being impeded by the soil pH or the overabundance of competing nutrients in the soil.

In general it is important to understand that the idea of fertilization is providing the nutrients that are lacking or are not available to the plant or are removed by the food production process AND restoring the balance between nutrients. One thing to note is that, in general, the nutrient mostly lacking in landscaping and horticultural applications where there's no significant removal of nutrients from the field in the form of produce, is nitrogen.

This post was edited by nikthegreek on Mon, Feb 24, 14 at 14:05

    Bookmark   February 24, 2014 at 2:04PM
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Hi Al,
thanks for your feedback. One thing to remember about organic gardening is that temperature & humidity can make all the difference in the microbial activity in the soil, and thus the amount of different nutrients available to the plant. You are in MI, and the cold temps there and the short growing season probably make organic gardening much slower and more difficult.

Here in this part of S. Florida, mulch turns to black soil in as little as 2-4 weeks, and soil in pots can break down very quickly. The sand here seems to just "eat" mulch. Many plants never stop growing and blooming, even in the dead of winter. Many of my roses prefer to bloom in winter here.

And of course you are right about the pH problem. I used to live in a spot that was solid limestone with barely any soil. There were many difficulties with growing there, but plants generally loved the commonly available water-soluble fertilizers with micros, especially acid-loving plants. Where I am now, plants die from that stuff.

If I'm overly-excited about micro supps, it's because I finally found something that works. And you're right, I need to avoid over-doing it! I am going to take your advice & look at a soil analysis- one is already available for our area.

thanks again,


    Bookmark   February 24, 2014 at 2:13PM
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tapla (mid-MI z5b-6a)

My regular referral to nutrient ratios was taking into account both minimizing EC/TDS w/o having to endure deficiencies on the container side and avoiding antagonisms across the board, so I'm with you there. Not many are so able to clearly delineate how different growing in the earth is compared to container culture. I always say that on a scale of 1-10, with growing in the earth a 1 and full hydroponics being a 10, conventional container culture would rate a 7 or 8.

I don't mean to stray from the topic, Avalon. I beg a pardon. I see you're in good hands with Nik to guide you. Some forums aren't so lucky. Wishing you the best with your growing adventures.


    Bookmark   February 24, 2014 at 2:22PM
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tapla (mid-MI z5b-6a)

Didn't see your post - sorry. I rely almost exclusively on organic methods in my gardens & beds, but not in containers. I use all the compost I can make and mulch heavily (2-3") with pine bark fines every other year (took 128 3 cu ft bags last year - 2 pallets).

Bonsai is my primary focus, but I do like my gardens & containers, too.


    Bookmark   February 24, 2014 at 3:17PM
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view1ny NY 6-7

Tapla, your garden looks amazing. Wow. It's so nice to see all that green.

Here in Brooklyn, we're all watching the snow melt but don't see any green yet.

    Bookmark   February 24, 2014 at 5:04PM
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sandandsun(9a FL)


You've got me curious because I am often thankful that I don't garden in south Florida since I've read SO many horror stories about that area. If you've found something that really helps that would be a possible breakthrough of course, possibly for Florida in general.

To be to able make up my own mind on the matter, I need more information. I'd appreciate knowing how long you've cultivated your garden space. I ask because you mention how readily mulch is broken down and the longer this has been going on.... Also, you state that the formula has little or no NPK; would you share the listed micronutrients and their percent concentration?

Thanks in advance and congratulations on your results whatever its cause.

This post was edited by sandandsun on Mon, Feb 24, 14 at 17:25

    Bookmark   February 24, 2014 at 5:19PM
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tapla (mid-MI z5b-6a)

Oh! Thanks for the kind words. We're buried under more than 2' still, even after the recent 3 day thaw (first since early DEC) .... and we're right back in the deep freeze, too. For the next week we're having sub-zero lows and day highs in the teens. It's gotta end PRETTY soon, eh? ;-)

Sorry, Avalon. Take care.

    Bookmark   February 24, 2014 at 5:23PM
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nikthegreek(9b/10a E of Athens, Greece)

Just a cautious warning about micronutrients. For some and dependent on the plant the line between deficiency and toxicity is quite narrow. I know it is a gross overkill for rose gardening but in commercial cultivation micronutrient deficiencies are diagnosed via leaf analysis and remedy is provided according to the type of plant.

    Bookmark   February 25, 2014 at 5:42AM
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To Al- thanks for the pics of your wonderful plants! Your Bonsai plants are just lovely, but I've never tried it myself. Hope the bad weather lets up very soon for you folks.

To Nik- Thanks for your reply. You're right about the micronutr toxicity- I'm being careful, applying 1 Tbls to 1/4 tsp at a time, with a week or more in between applications, and repeating only if the plant's color isn't good.

to SandandSun
to answer your questions about the conditions here so you can make a better decision about the micronutrients:

I've been cultivating this particular garden here for 8 years, adding truckfuls of rotted mulch provided by the county (not nice clean, pine bark fines- real detritus!).

Other conditions: No freezes, sand which is really finely crushed shells, salt spray, very windy, periods of too much rain, not enough rain, foggy when colder weather sets in. This "soil" won't hold water at all unless augmented with a great deal of organic material. The roses all have circular berms of soil around them to direct the water toward the roots.

Black spot is a problem, but most of my roses here manage to "grow through" it.

Now about the micronutrients I've been using:

Percentages on bag: nitrogen 1%, Phosphorous 0%, Potash 1%, calcium 12%, sulphur 10%, iron 4.5%, boron .02%, manganese .1096%, molybdenum .0005%, Zn .10%

I'm being very careful to make the applications small- 1tbs or less to start, wait a week or more, evaluate the color and growth, then 1 tsp -1/4 tsp more, if warranted.

It's a little bit of a guessing game, because some roses have dark green foliage and some are lighter, so I'm judging the plant to see if it looks "right" to me, according to the pictures and descriptions of that particular rose.

Hope this helps,


    Bookmark   February 25, 2014 at 10:41AM
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nikthegreek(9b/10a E of Athens, Greece)

If it works for you just go for it. You're obviously providing enough N (and K maybe) with your composting and mulching so if your micronutrient feeding seems to complete the picture just keep on doing it. It is just that what works for somebody might be a total disaster for someone else. I would try feeding the roses foliarly with this stuff if I were you (provided that this use is prescribed on the label). You will find that you will need less.

This post was edited by nikthegreek on Tue, Feb 25, 14 at 13:03

    Bookmark   February 25, 2014 at 12:53PM
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sandandsun(9a FL)


Thank you for the information. I am unable to make any immediate conclusion, and my only immediate observations are 1: most of Florida requires 0% calcium so it isn't the calcium and 2: the iron component is interesting.

My only other comment is that I would not discount the beneficial effects of 8 years of adding moisture retaining and nutrient available organic materials to sand.

Wait, another thought: if you have "salt spray" you are possibly getting some micronutrients from that already since most sea salt isn't usually purely NaCl (table salt).

Hmm, I really wonder about the iron factor. An interesting experiment would be if you could find a product containing only iron sulfate and use that on a control group to compare the results.

Thank you very much for sharing your information!

If you decide to have a soil analysis done, it would be most interesting if you could have two done - one from rose soil that has been treated with your micronutrient application and one from a part of the GARDEN without roses and without treatment. I'd be particularly interested in the pH and the iron analyses; the comparison might be revealing.

Thanks again and best wishes for continued success.

Here is a link that might be useful: Basic Plant Requirements

    Bookmark   February 25, 2014 at 1:43PM
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nikthegreek(9b/10a E of Athens, Greece)

Iron sulphate is mainly of use if provided by foliar application. For ground applications chelated iron of a suitable to soil pH formulation is the prefered way of iron delivery.

    Bookmark   February 25, 2014 at 1:49PM
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Nik- I do use foliar on fruit trees but not on the roses. I have heard that it can damage or discolor the flowers, but I don't know if that is true or not. This particular preparation I'm using on the roses cannot be made into a foliar solution. I can try the foliar on my Pink Cracker rose, and see what results I get. Pink Cracker is my experimentation rose, because it grows like a weed here and takes very easily from cuttings- I have several of them, and can replace it, if necessary.

And of course, you are correct, what is working for me here in this microclimate might be just the wrong thing for other rose growers. I was really just wondering if anyone else had tried this approach, and if so, what were the results.

sandandsun- Yes, the addition of 8 years of compost has helped enormously, but the micronutrient application caused an immediate, distinct and undeniable improvement in the plants- in some of the bushes, it was literally overnight. I'm wondering if the supplement affected the pH of the mulch, and allowed the release of some nutrients that were locked up. That was a major problem in one area where I previously lived.

And you are right about the calcium, of course- my "shell yard" certainly doesn't need more of that!

(By the way, the source of iron in the mix is ferrous sulfate.)

Well, time will tell...who knows, maybe I'll be posting in a month to tell you that all my roses look awful! Right now, they are healthier than they have ever been and I have never had this many buds before.

    Bookmark   February 25, 2014 at 2:49PM
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