soil pH ranges?

I could use some help ASAP. A couple of suggestions have been made to add pH requirements to the Plants Database entries. A very good idea, I just need to know if there is a standard set of ranges, or if it should look something like this (feel free to chime in with your suggested modifications, please!)

Very Acidic (below 5.0)
Acidic (5.0 - 6.0)
Neutral (6.0 - 7.0)
Alkaline (7.0 - 8.0)
Very Alkaline (above 8.0)

Here's one question that came to mind: can ANY plant be grown successfully at either end of the scale (below 5.0 or above 8.0, in my example above)?

If not, I'm thinking we shouldn't even list them as options that could be checked...

Thanks in advance for your feedback and ideas.

go_vols, blueberries grow in soils with pH < 5 and mesquite grows in soils > 8, so at least these two grow at the ends of the spectrum. I suspect a bunch more do also. One suggestion, neutral is 7 and anything below is acidic and anything above is basic (or alkaline). You might want to add two more categories - slightly acidic (6.5-6.9) and slightly alkaline (7.1-7.5)

I agree.

Just explain that it is a linear scale above and below pH7 without distinct steps.
You are gradually getting more alkaline above and more acid below.
Extremes of either end of the scale is of little relevence to the home gardener.

Unless the compiler is sure what pH level is best suited to his/her dbase entry it could end up a very misleading inovation.
Also, plants have tollerance which varies in magnitude between types genera and species.
I would stick rigidly to - 6.5-7.0 regard as neutral; 7.0-8.0 alkaline; and 6.5-5.5 acid. And leave it at that.

Why not just state this in an intro to the database rather than trying to quantify each plants requirement.

Peter.

The reason for adding soil pH is because someone reading an entry in the database may wish to search for plants that are within a certain pH range (and may also share other characteristics such as sun/shade requirements, moisture requirements, etc.)

You'll be able to check as many pH ranges as apply to a particular plant, for those plants that have a wide tolerance range. And if you don't know what the requirements are, you can leave this section blank for someone else to fill in later :)

Here's what I think I'm hearing for a modified version:

Very Acidic (below 5.0)
Acidic (5.0 - 5.5)
Slightly Acidic (5.5 - 6.5)
Neutral (6.5 - 7.0)
Slightly Alkaline (7.0 - 7.5)
Alkaline (7.5 - 8.0)
Very Alkaline (above 8.0)

I realize neutral is truly only 7.0 (no range), but is it acceptable to give it a range for this purpose? Any other comments/suggestions/changes? Please advise!

I believe that sums it up extremely well Vols. That would be the scale that I would go by. If you wanted to give any leverage then "neutral" could go two points beyond either side of 7 (6.8-7.2). This reasoning being because of the difficulty involved in the determining factor of "points of pH" and just how much it affects plant growth.

I'm in agreement with the ***slightly acidic***(6.5-6.9) or ***slightly alkaline***(7.1-7.5) Elaine

You have to keep in mind that pH is on a logarithmic scale. So going from pH of 7 to pH of 6 means that the soil is 10x's more acidic and going from 7 to 5 it is 100x's more acidic. So, if one agrees that neutral is slightly more than 6.8 to slightly less than 7.2, then the slightly acidic should be 6.5 to 6.8 and slightly alkaline should be 7.2 to 7.5.

Rather than calling them slightly acidic, acidic, very acidic, etc., why not just have the pH ranges as a search criteria? This would be totally unambiguous and not dependent upon the pH range one views as "slightly" acidic, etc., which can obviously vary from one person to the next as evidenced by this thread.

Also, with this approach Dave could set up the database such that a plant that grows in a pH range of 5.5 to 8.0 would appear in whatever pH range someone was searching for.

Let me take another stab at this. You can like or dislike the descriptive terms attached (personally I think they're helpful for those not as familiar with the pH chart as others.)

With or without the descriptors, this is a more detailed (precise) list of ranges, from another source (I found it in my own journal from last year, LOL.)

4.5 or below - very acid
4.6 to 5.0 - highly acid
5.1 to 5.5 - strongly acid
5.6 to 6.0 - fairly acid
6.1 to 6.5 - mildly acid
6.6 to 7.5 - neutral
7.6 to 7.8 - mildly alkaline
7.9 to 8.5 - fairly alkaline
8.6 to 9.0 - strongly alkaline
over 9.1 - very alkaline

I hear what ya'll are saying about narrowingg down the "slightly acid" "neutral" and "slightly alkaline" categories. Semantics aside, are there plants that absolutely require a range of 6.5 to 6.8? And they will not grow/thrive if the soil pH is 6.4 or 6.9?

Most of the scales I find in my resources and on the web use a full or half-point increment (6.0-7.0 or 6.0-6.5, 6.5-7.0) as their basis.

So unless someone really thinks we're going to be held accountable for killing plants by using the scale above, I'd like to propose we use it :)

Terry there are quite a number of plants that will not tolerate anything other than a certain pH. Especially in the case of acid soils. Alkaline and neutral suit most plants!! Would a list of acid loving plants help at all? I'm sure I could provide this if needed!!

Louisa, I agree that certain plants require more acidic soils; I don't fully agree that "there are quite a number of plants that will not tolerate anything other than a certain pH." Most plants will grow within a given range, perhaps varying as much as a full point or more.

Even azaleas, which do need acidic soil, can be successfully grown in a range that goes from 4.0 (or even lower) to 5.5 or a bit higher.

My plea above is to step back and examine what we're using these ranges for: to provide advice on the general pH requirements of a given plant. I don't think we need to use ultra-narrow ranges (6.5 to 6.8, etc.) to accomplish that goal. If a plant would grow in a range of 6.5 to 6.8, I would argue that it would also grow quite well in soil with a pH of 6.9 or 7.0 :)

There I go again - me taking the short cut and not explaining myself fully!! Let's say, to make it short again, I agree with you!! My first sentence should just have read - acidic!!

(((Louisa))) I'm being terribly crabby today; I'm so sorry. I'm just trying to get this aspect of the database upgrade wrapped up, along with several other "loose ends" and to top it off, the rain is hampering my ability to get my gardens in this week :(

Does anybody have any changes to the last set of ranges I proposed? (Do you dare? *grin*) Seriously, if you do, speak up.

If I don't see any more activity on this thread by late afternoon today, I'm going to go ahead and add them at that time. Thanks again for your input - you've certainly made me dig a little deeper for the answers!

go-vols, I think, that its enough to use the gardener rules.

ph 7 = neutral

ph 6 = slightly acid (schwach sauer (german) weak acid

ph 5 = acid

ph 4 = strongly acid (stark sauer)


ph 8 = slightly basic (alkaline) leicht basisch oder alkalisch

over ph 8 basic or alkaline.

My favorite, Brugmansias, a tropic to subtropic plants, thrives very well in ph between 6,5 - 7,5. It tolerates 6 but the flowers are lacking color and the growth slows down.
I dont think, that you do not need to do it so precisely.

Thanks, Monika! (I love the German translation, too!)

Even if with the half-point ranges, you can check more than one range. Plants that will do well in one-point-or-wider range will show their full spectrum of suitable soil pH levels.

I really do appreciate the feedback and help with this part of the plants database; I'm sorry if I came out barking earlier today :) I know Dave's excited to show off the new version of the database, so when he unveils it, I hope everyone will take a tour, look at some of the entries, and maybe even dabble a bit in it! (Add the proper soil pH levels to some plant entries while you're in there, please!!!)

The trouble with me is that I have to rely on memory and just have not the time to wade through reference books to look this up and that up, whether it's plant ID or information you need to enhance DG. There are some folk that do retain all the info they read or have experience with and can recite it backwards!! Knowing that my memory is getting worse by the minute, I think I'll just keep quiet!! As for supplying the names of plants that like acidic soil, again I should have made myself clear. I didn't mean in connection with your current endeavour but rather on the lines of something to think of down the road a bit.