Lime with partially acidic plants?

MiniGerdener876April 1, 2013

I'm using a mixture of pine bark, compost, and peat moss (about equal proportions, slightly more pine bark) in my container/raised bed. I can't get all the correct ingredients for either of Al's mixes so I settled with this. I might add Perlite also if its not light enough. I'm growing tomatoes, carrots, a mix of lettuces, and garlic in the bed. From what I've read these vegetables like more acidic soil I believe? Should I still add lime? I was going to use the Espoma lime if needed. It's an organic garden.

I'm also hoping to use this same mix with strawberries, mint, and miniature roses. They're in separate containers though.

This post was edited by MiniGerdener876 on Mon, Apr 1, 13 at 21:36

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shazaam(NC 7B)

The pH for pine bark and peat moss is in the 4 to 5 range, so, even if your compost is neutral, your combined pH is still likely to be at the lower end of what's ideal for vegetable crops in garden soil. That being said, I've seen Al (tapla) make the point that pH in container media isn't nearly as important is it is in the ground, and that a slightly lower pH is preferable when growing in containers. So, raising the pH with lime might not be essential, but, unless your fertilizer provides Ca and Mg, I'm not sure that I'd recommend leaving it out entirely.

I've provided a link (below) to an older thread that might be helpful.

Here is a link that might be useful: pH in Al's 5-1-1 Mix

This post was edited by shazaam on Tue, Apr 2, 13 at 16:08

    Bookmark   April 2, 2013 at 3:53PM
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The fertilizer I'm using is the Espoma garden tone which does have calcium and magnesium, along with that I'm using fish emulsion also. That link was interesting, thank uou for it. I'm thinking I should be ok then.

    Bookmark   April 2, 2013 at 7:03PM
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greenman28 NorCal 7b/8a

I recommend that you add the Lime.

I add the Lime, I add some Osmocote, and I also supplement fertilization with Foliage Pro (which also provides Calcium and Magnesium).


    Bookmark   April 3, 2013 at 3:44PM
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DWD2(10a, Sunset 17)

MiniGerderner876, If you have a raised bed, I think you would be far better off growing in properly amended soil rather than a bark based media. In my experience that is more challenging to grow organically in a bark dominated media. I have never grown garlic, but I grow the other 3 regularly. In fact, I have starts of 35 different tomato varieties & 11 lettuces going right now. You want a growth media (be it soil or potting mix) of pH 6.0 to 6.5 for tomatoes, carrots & lettuces. Like many plants they will tolerate a wider range.

When I grow these items in pots, I use off the shelf potting media that I then amend with organic products. Make sure to keep your mint in its own pot as it is pretty aggressive.

shazaam, pH management in containers is just as important as in ground and I believe you can make the case that it is more challenging to manage in containers. I am unaware of ANY plant that has a different pH optimum in container media versus soil. That assertion just defies logic. Why would a plant grow better in a container at a pH lower than its optimum?

    Bookmark   April 5, 2013 at 3:26AM
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shazaam(NC 7B)

Have you read the linked thread, DWD2? If not, here's an excerpt from one of Al's posts...

Basically, in mineral (garden) soils, the micro-nutrients are already IN the soil, and the ideal pH is a happy medium where all the elements are in a favorable part of their availability range. Too much deviation either upward or downward in the pH level can have a significant impact on availability and toxicities.

In container media, the organic components contain only very small amounts of micro-nutrients, locked securely in the hydrocarbon chains of the medium. So, raising or lowering the pH of the medium or the soil solution has little impact on the availability of these nutrients.

If you point to a pH induced Fe deficiency and say Hey, look here - a pH induced deficiency", I'll point to the fact that technically it's not a function of the pH, but of the presence of high concentrations of Ca, Mg, Na, or bicarbonates, with the increase in pH being only the symptom.

If you could use a medium that is devoid of potential toxicities, and has all the essential nutrients in the right ratio, you can grow most plants very well (in container media) at pH ranges from 3.0 to about 8.5.

He also includes two very informative charts of nutrient availability by pH that suggest that the...

'ideal' container media pH is about 1 full point lower than what is considered the 'ideal' pH for garden/mineral soils.

As usual, he does a good job of pointing out that growing in an organic-based potting mix (bark, peat, etc.) is very different than growing in mineral-based garden soil and that what works in one isn't necessarily ideal in the other.

If you'd like corroboration from an outside expert, here's an excerpt from Robert R. Tripepi, an Associate Professor in the Plant Science Division at the University of Idaho:

Plants can be grown in a pH range between pH 4 and 8, if micronutrients are maintained in available form. The pH range for plants grown in organic soils or soilless mixes is around 1.0 to 1.5 pH units lower than the pH range for plants grown in mineral soils due to differences in nutrient availability. Nutrient availability is higher in soilless mixes around pH 5.0 to 5.5.

I've provided a link to the full paper below.

Here is a link that might be useful: What Is Your Substrate Trying to Tell You

This post was edited by shazaam on Fri, Apr 5, 13 at 10:35

    Bookmark   April 5, 2013 at 9:38AM
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greenman28 NorCal 7b/8a

Thank you, Shazaam.


    Bookmark   April 5, 2013 at 11:09AM
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DWD2, it's basically a raised bed with insect fiberglass screen on the bottom, it's off the ground though.

I decided I'll just make the mix, pH test it and go from there to see if it needs changing. I don't want it to be to acidic or alkaline.

    Bookmark   April 5, 2013 at 5:11PM
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DWD2(10a, Sunset 17)

Shazaam, I read a lot of horticultural literature and I usually depend on it for my understanding of how plants and soils interact.

The first paragraph in the excerpt you quote is clearly amiss. The amount of macro and micro nutrients in mineral soils varies tremendously. There is a HUGE industry built around soil analysis for soil quality. Many state Cooperative Extensions offer free soil testing for people in their state. In case you are unfamiliar with this fact, ATTRA maintains a list of such places that you can find here:
The notion in that first paragraph that all plants have very similar optimal pH ranges for growth is well known to be incorrect. Blueberries have a pH optimum around 4.5 both in mineral soil and bark plus peat moss based mixes in containers while crocus performs best around pH 6.5. At a common sense level it is a nonsense notion too. Stop and think of all the plants growing in the hugh array of soil environments around the world. There are plants that have evolved to grow in pretty acidic soils while others can grow in basic soils and everything in between. Figure 5 in this link shows the range of pH optimums for a broad array of horticulture crops:
As you can see, there is approximately a 2 pH unit difference (100x difference in H+ concentration) between Crossandra and Venus Fly Trap. Here are 2 links presenting optimum pH range differences between Geraniums and Pansies:
Note their target pH ranges do not overlap.
It is true that, for any individual plant under a set group of growth conditions, varying pH above or below its optimum range has negative consequences for the plant, but, as I read paragraph one, it appears the statement is directed to the collection of all plants, not an individual.

The statement in paragraph 2 is known to be incorrect. In this publication it is shown that there are sufficient micronutrients in Douglas fir bark to support vinca growth.
AND that micronutrient availability is pH dependent. I have dozens of other publications from peer-review, scientific journals showing exactly the same thing. pH management in container media is critical. My best guess is that many, maybe most, of the difficulties people bring to the GardenWeb have their source in poor pH management.

Paragraph 3 of your excerpt is, once again, incorrect. The pH effect on iron (Fe) deficiencies is firmly established. Here are 2 examples:

I have no idea what is meant by the fantasy situation described in paragraph 4 and why a plant would feel no pH impacts without consideration to nutrients and nutrient toxicities.

The excerpt that refers to an" 'ideal' container media pH' comes from a paper published by Lucas and Davis in 1961 in Soil Science. In that paper, they did demonstrate that ideal pH ranges for the mineral soil they used versus wood-sedge soil and sphagnum peat soil was about 1 pH unit different. As more work has been done, it has become clear that the story across a broad range of mineral soils and organic soils (container soils) is far more complex. There is HUGE variation across soil types and those variations significantly impact the ideal pH range of that medium for each plant. The 1 pH unit "rule" has to assume there is only one mineral soil and one container soil which is just silly.

For anyone who truly cares to understand pH management, I highly recommend this book:
It will be a well spent $20.

Thank you for the link to Dr. Tripepi's paper. I checked his publication record. I can find no publication by him on pH management in a peer-reviewed, or any, journal. I think he is not so up to date.

In rereading my post above, part of what I said to you was poorly stated and I apologize for that. What I was referring to in the later part was that any given plant's fundamental abilities to acquire nutrients do not typically change from media to media. An acid loving plant is an acid loving plant. It is the varying qualities of the different medias that will result in pH shifts to allow optimal access to nutrition by a plant. Another publication on the subject written for a more general audience is this:

One more thing. Please notice that in all my posts I try to provide links to the authoritative sources I depend upon to make my growing decisions and that support my thoughts. If I am running a line of nonsense, I try to give you the ability to catch that and correct what I said. I choose to depend on those types of sources of information that provide support for what they say. Of course, others can decide what works for them.

MiniGerderner876, I apologize for your question getting so deflected here. I would still advise going with a mineral soil in your raised beds and using a purchased potting soil for your pots for what you want to grow. A lot of universities have excellent sources of information on growing all sorts of things in soil and in pots. The University of Florida:
and North Carolina State University:
are my 2 favorites. They are the Stanford and Havard of horticultural science in my opinion. They have tons of useful, absolutely dependable information available for free. Good luck with your garden!

    Bookmark   April 5, 2013 at 6:45PM
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DWD2(10a, Sunset 17)

MiniGerderner876, Ooops. Missed your new post while writing.

Cool. I hope it works for you & either way you learn to do it better yet next year. Which is always my goal. Here is a link to what I think is some great tomato advice:

    Bookmark   April 5, 2013 at 6:52PM
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