Acidic soil staying power

San Antonio, TX(Zone 8b)

Hi we have very alkaline soil out here but the kids want blueberries. I want to dig up a corner of the backyard and drop a yard of Rose Soil (Acidic) so they can grow. Now is this goint to be a 1-time thing for me? Will the new acidic soil stay that way or will the natural alkaline soil slowly take over and I will be having problems in a year or two?


Harvard, IL(Zone 5a)

You're going to have to regularly monitor the pH of your soil. Periodic applications of an acidifier such as Miracid, or mulching with pine needles or oak leaves won't hurt.

Dallas, GA

In addition to what FertiSorb said, top-dress with used coffee grounds (you can get them for free by the bagfull from Starbucks). They'll help to keep your soil acidic.

North Ridgeville, OH(Zone 5b)

Contrary to popular belief, used coffee grounds aren't very acidic at all. They're almost exactly neutral on the pH scale.

Mid-Cape, MA(Zone 7a)

Puddle, that was the MOST informative article on coffee grounds and composting! I had no idea that coffee grounds weren't acidic, and that they should be composted with leaves for carbon.

North Ridgeville, OH(Zone 5b)

My pleasure! I mix mine with tons of shredded paper, which is what I have a never-ending supply of.

San Antonio, TX(Zone 8b)

OK thanks for the info folks, I guess I will dump the acidic soil there and grow a few plants. I can mulch with xmas tree remains every year and hopefully I can leave it at that...

Mid-Cape, MA(Zone 7a)

Ratfood, is your alkaline soil sandy? I learned that nutrients leach away very quickly in sandy soil (which is what we mostly have here on the Cape.)
I went to a Master Gardener's class today on soil chemistry, and what I learned was that you can indeed manage your soil to increase the pH but you do need to monitor it regularly, as Fertisorb mentions, to keep it as acidic as you wish.
You probably don't want to mess with containers, but there are several blueberries that do grow well in containers. You can use nice peat-based container soil mixes.

San Antonio, TX(Zone 8b)

Heya Capecod,

I need to try one of those classes!

The native soil I have now is alkaline clay. I was planning to dig it all out about 10" down and drop a cubic yard of acidic soil in that spot mounding up to about 10" high. That would give 20" deep of acidic soil and under that layer would be alkaline clay... I am only growing 3-4 blueberry plants tops so it should be fairly simple, but I don't have the time nor wherewithal to babysit the soil for them. I can easily drop compost on them two times a year like the rest of the garden to keep the nutrients up though.

Thats why I wanted to swap out the soil instead of slowly changing it. I am looking for a quick fix here if it is at all possible. Containers are no longer an option because of the heat we have out here, they dry out faster than I can water them (sometimes I am at work for 2-1/2 days straight and can't get to the garden at all). I am looking into drip irrigation this year but the berries are nowhere near the spot I am doing that at.

Thanks for the help folks...

North Ridgeville, OH(Zone 5b)

Building a raised bed would be a whole lot easier. I have heavy clay soil here, and I know what a pain in the butt it can be.

Glenwood Springs, CO(Zone 5b)


One of the things that will affect your "acid" soil is your irrigation water. The calcium and magnesium, (most common hard water components) will tend to react with hydrogen ions in your soil, neutralizing them and thus changing your acid soil to a more basic soil. Call your water department and ask for a consumer confidence report. This report will tell you what is in your water & most importantly what your water's pH is. Get a pH meter from your local nursery. You want your soil to be between 4.0-4.5 pH.

When you start dealing with soil pH, the chemistry of the interactions between nutrients and pH can quickly become bewildering as CapeCodGardener can probably tell you.

A good primer on blueberries

I assume that the soil must have good drainage, but blueberries like moist soil, soooo I would add acidified cotton boll compost to your "Rose Soil" on a regular basis. The acidified cotton boll compost you want to get is made by Back to Nature of Slaton, TX. Add some greensand to your soil mix in order to achieve a good supply of micronutrients.

Good Luck! Make the kids help, they will learn a lot of good lessons.


This message was edited May 9, 2010 12:28 PM

Las Vegas, NV(Zone 9a)

I am growing blueberries but they are in very large, and I mean large pots. The pots came off a golf course and were free. Blueberries have shallow roots. My pots are between the house and the fence so the bottom of the pots are in partial shade and the plants are in muted sun filtering through pine trees next door. The biggest problem is how much cold weather do you have. I purchased a new variety that needs less days of cold weather. They are blooming right now, so I will keep my fingers crossed and let you know. I have mine hooked up to irrigation and I check th ph twice a month but remember, the roots do not go deep so there would be less soil to keep higher in acid.

Mid-Cape, MA(Zone 7a)

Pewjumper sounds like he (she?) could have taught the class I just took! The advice on how your local water can affect the pH of soil is also something that I learned about. You need to know exactly what the pH of your water is. Apparently here on the Cape "town water" is now required to be pH neutral at 7. Possibly your local County Extension Office could also give you advice. Our local Barnstable County Extension Office has a soil expert on staff.
Personally, I think I would just build a raised bed, as Puddle suggests! ;-)

San Antonio, TX(Zone 8b)

OK thanks folks, lots of great info here. Sounds like i'll be building another raised bed~ I'llalso look for Sharons warm blueberries...

Dallas, GA

Quote from PuddlePirate :
Contrary to popular belief, used coffee grounds aren't very acidic at all. They're almost exactly neutral on the pH scale.

Correct; used coffee grounds themselves are not highly acidic (the acidity is removed during the brewing process), but they nonetheless appear to have a gradual acidifying effect on the soil over time. I've been using them on my hydrangeas for the past two years and they gradually turned from pink to purple to blue. I haven't tested the hydrangeas' soil since first planting them, but the color change alone indicates that the soil they're growing in has become more acidic.

The reason for this gradual acidifying effect may have to do with earthworms.

Normally, worm castings are pH-neutral or slightly alkaline. When worms' consumption of "greens" goes up, their castings become more acidic. As any vermicomposter knows, worms love coffee grounds which are certainly very much a "green" (nitrogen-rich). So, it stands to reason that, as earthworms consume the UCG's then tunnel back down leaving their more acidic castings behind, the soil would become (over a long period of time) more acidic. Whatever the scientific reason, they break down beautifully and bump up the earthworm activity, and as long as they keep my beautiful hydrangeas blue, I don't plan to stop top-dressing with UCG's any time soon!

This message was edited Feb 14, 2010 8:35 PM

Mid-Cape, MA(Zone 7a)

That's very interesting, Mrs.Johnny. I have some hydrangeas that I'd like to encourage to become/stay blue. You mention that you top-dress with them. Does this mean you just scatter them around the top of the soil around your hydrangeas? Or do you mix them with compost?
Thanks in advance.

Dallas, GA

I just dump them around the top of the soil around the hydrangeas. I also compost any extra used coffee grounds (e.g. in the compost bin... I don't mix them uncomposted into soil I'm planting in).

If you spread them around your plants then put mulch over them, try a week or two later peeling back the mulch... bet you'll see some busy, happy earthworms!!

Mid-Cape, MA(Zone 7a)

I can do that! Thanks for the clarification about spreading the coffee grounds and then covering with mulch, or adding them to the compost bin. I note that in the article that PuddlePirate listed, the same advice was given-- and when I get TWO reliable sources that agree, I know I'm on the right track.
Ratfood, do keep us posted on your new blueberry-garden. I've learned a lot from your thread. Thanks for your questions!

San Antonio, TX(Zone 8b)

OK I dug out the bed today and lined it with landscape timbers two high. That gave me a bed about 12 -14" deep. I filled it with the "rose soil" from Gardenville.

Heres what it says:
Rose Soil is a mix of Compost, aged Pine Bark, Iron rich Red Sand, Rice Hulls, Composted Top Soil and Orange Sand. Great for all acid loving plants and fruit trees.

I put three blueberry plants in there, I also saved my xmas tree so I will use those pine needles to mulch it. I'll get some pictures up in a day or two.


Las Vegas, NV(Zone 9a)

Sounds like you are on your way. I am planting my tomatoes outside tomorrow. They will be covered with domes. Actually the temperature is OK but the wind picks up this time of year. The photo was my tomatoes last year.

Thumbnail by WormsLovSharon
Helena, MT

RF, as your responders have said, blueberries are a high maintenance crop. I have been toying with the idea of planting blueberries for several years now. As WLSharon has indicated, the cultivators for your area are much different than the ones we deal with in the north country, however the process of development in similar. One pH is critical and two it takes three years to establish a plant before you can harvest berries. I would agree with Sharon that potting may be the best solution for maintaining a proper pH level in the soil. Potting of the smaller varieties can also allow you to relocate the plants in extreem heat if necessary. Regular checks of pH are advised so I suggest you invest in a decent pH test kit and a soil sample probe as well. The pH results from laboratories are unreliable if your want to maintain a pH below 5.0. Since pH is a measure of the Hydrogen ion concentration, testing should be done within 15 minutes of taking the sample. And I would recommend that you take samples from below the six inch depth in your soil regardless of weather the plant is potted or directely planted in the soil.

Soil prepartation typically takes a year to get the proper balance of pH if you are planning on planting directly. Constantly trying to adjust pH in your soil using soil sulfer compounds in the first year are not advised. If you have ever considered raisling euro worms or red wigglers in a vermiculture process, you minght consider using peat moss as your media. Presoaked peat moss makes a good media, which can later be used for making germination and potting mixes, and the water fromt he presoaked peat moss can be used to water your blueberry plants. This would be a simpler and more effective means of maintaining a lower pH without the huge jumps from sulfur based compounds. Keep in mind too RF, that the first two years require removal of the flowers in order to develope a suitable root base for these plants to develop fruit properly.

Mid-Cape, MA(Zone 7a)

Regular checks of pH are advised so I suggest you invest in a decent pH test kit and a soil sample probe as well.

mraider, can you recommend a decent pH test kit? I see them around but don't know what a good one would be.
And thanks for all the info on blueberries. I have two dwarf varieties in 15-gal. containers--had them in two years--but didn't know about the need for flower removal for root development. The birds do a good job of fruit removal ;-)

San Antonio, TX(Zone 8b)

OK thanks for info, I am interested in the decent pH kit also if anyone has a model they like. If I can't get them blueberries to stay alive I will have to put in blackberries or rasberries, but i'll give it a fair shot in the meantime.

Also, Sharon, what are these domes you speak of? I need some but 2L soda bottles aren't big enough and I want to drop my maters in the dirt. Do you have any pictures?

Have a great weekend folks!

Las Vegas, NV(Zone 9a)

They are clear plastic and I got them at a nursery last year. They look like the English Glass domes but are inexpensive. I will take a photo if I use one this year.

Mraider3, if my blueberry plants were two year old stock do I only need to take off blooms for one year or three. I do not know If I will live long enough if it is three years.

It is raining here and we need that badly so I am organizing all of my gardening "Stuff". I need another two car garage. I already have one section of a three car garage. My DH needs to get rid of his car...

Helena, MT

The $10 plants you order on line or through seed catalogs are probably one year stock. One seed company sells "Jumbos' which are two year old stock. The dwarfs are typcially one year old stock. Unless you purchase your plants from a local nursery, I doubt you will get anything larger than two year old stock, which obviously has a larger root ball. I know you well enough Sharon to know that your potted plants are probably ready to set fruit in those three foot deep pots of yours, and you will more than likely outlive those plants which are probably good for fourteen years with your TLC.

As for pH monitoring I would suggest that you no invest in a pH meter with phrobe. It has been a few years since my lab days, but we had to recalibrate our pH meteres daily and they were a pain in the butt. A colormetric type kit is your best bet. Some just have color charts and the more expensive (Hach) can be purchased with a color wheel. The color charts are just fine. You could even use litmus paper for a quick check now and then, but it is probably best to have a decent kit on hand for making soil adjustments, i.e., adding sulfur base compounds, which should be done every couple of years. The thing most people don't realize about pH is the volatile nature of the Hydorgen ion. Not only does the pH of a sample change after about 15 minutes, there is a diffenence between the top four to six inches of you soil and the say down around 12 to 24 inches which is the root zone of the two or three year old plants. You have read in various responses in this thread and possible others about adding coffee grounds, peat moss, or possibly other acedic compounds to the top surface of you pots or garden plants and carefully cultivating it in several inches so as not to disturbe the roots of the plant(s). This procedure is fine, but again the top six inches may be within the pH parameters of the particular plant, however the bulk of the root zone may not be. I have only seen one seed catalog which offeres a decent soil phrobe and I can't remember which one it was. There are numerous laboratory supplie houses on line which will more than likely carry soil phrobes which go down 24 inches which is my recommendation for serious gardeners. Not cheap, but you will never need to buy another one...they will last a life time. The beauty of the professional type phrobe is that you can take a one inch core sample form any depth and check your pH to see what the effect of your soil additives are on pH adjustments. But give the soil time to adjust after adding sulfate compounds. The initial effect is not what you are looking for. pH stabilization takes time and that is why several of the university studies I have read recommend taking a year make the proper adjustments to establish a pH in the range of 5 or less for blueberries.

Like Sharon, I don't know if I will be around in three years to see my blueberries yield or not, but I have considered just planting them as ornamentals and not worry about weather they yield that many berries or not. But again, if you want to make jams, jellies, and juice for the kids you should work to establish a good root growth first and be patient. Like you mentioned RF, I planted rasberries first and was picking the second year. This year will be their third year and I am expecting a bumper crop if all things fo well. Just wish I could grow blackberries here. I have a sixty foot row which has been adjusted for pH and blueberries, however I am going to use Sharons method of just potting them in three foot deep fiberglass pots from Lowes. The strip will just have to be used for something else...

Raleigh, NC

I seldom have to use it here, but I used to use sulfur a lot (in a container labeled rattlesnake sulfur) to acidify a small amount of soil for a particular plant when I had basic soil. The beauty of using sulfur on a spot basis is that it has cleanser qualities to it, a natural medicine, helps with fungus and bacteria issues.

Glenwood Springs, CO(Zone 5b)

I have a lower garden where the "dirt" was brought in to raise up the side yard. Lots of rocks. I did a rough soil test in my lab and it came out at 8.25 pH! I mixed up a strained sample of my "dirt" with compost & peat moss. It came back from a soil lab with a pH of 7.43. So last fall after some calculations I decided to add 50 lbs. of sulfur to an area that is 30'X60'. I will mix up another sample for lab tests in the summer as it takes sulfur fixing bacteria a while to break down elemental sulfur.

You are correct when you talk about a cleansing affect on the soil when sulfur is used, as it is also used as a fungicide. Unless you have problems like mine and some time. I would recommend peat moss as an alternative to sulfur. Remember, over time, ammonia (NH3) is broken down by soil bacteria into nitrates & nitrites that plants can use. As this goes on the pH will be gradually lowered. Rain & snow is also a little on the acidic side. When organic material is broken down, it also contributes carbonic acid. Pine needles & oak leafs are some of the best for slowly changing soil pH while adding organic matter to the soil.

If you are using sulfur, I recommend repopulating your soil in a year or so by using Dr. Earth fertilizer. It contains carefully selected bacteria, fungus & mychorizae to help your soil come back to life.


Plano, TX(Zone 8a)

You can also water with a vinegar solution to raise acidity. Two tablespoons of cider vinegar in a gallon of water is the formula I believe I've read in the past.

This message was edited Feb 23, 2010 9:27 AM


Research done by many people including Dr. Abigail Manynard at the UCONN Agricultural Research Station in New Haven, Conn has shown that there is no significant change in soil pH after years of adding oak leaves or pine needles to that soil.

Glenwood Springs, CO(Zone 5b)

I would love to see the article as it is contrary to everything I have read in the past concerning gardening.

The interaction of water, soil & microbes is extremely complex. I still have much to learn when it comes to my field of water & wastewater treatment. The similarities between pedology and wastewater treatment are very surprising. If you have high levels of calcium carbonate, (CaCo3) the soil will resist changes in pH.

I will google the good doctor and see what she has to say. Maybe she has some good suggestions on pH correction in our basic western soils.

I sent Dr. Maynard an e-mail on Sunday, May 9.


This message was edited May 9, 2010 6:33 AM

Nurmo, Finland(Zone 4b)

A good point about your local water supply. I used to live in an area with fairly neutral soil; but our tap water came from a reservoir several miles away in the Chiltern Hills, which are solid chalk. It was so alkaline it was almost off the scale! Kettles used to fur up in no time. However, every cloud has a silver lining. Heart attacks are less common in hard water districts.

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