Acidic soil for blueberries

7 years ago

last modified: 7 years ago

Hello,

I was wondering if I can get a few pointers about how to acidify the soil for blueberries. I have about 21 different varieties of blueberries I have. I planted them in containers ranging from 9 gallon to 20 gallon containers. This is due to heavy clay soil in my yard. Basically, I used peat moss, garden compost, perlite and black gold organic potting soil and I mixed them together. I have a ph meter that I bought for $10. And it read between 6.5 and 7. I had a few trees that I chopped down last year, so removed the top 6 inches of the soil around the blueberries and mixed the removed soil with wood chips and pine needles and refilled the pots. I also added a few inchest of pine needles as mulch around the plants. The ph meter still read 7. So then I added soil acidifier which contain sulfur a few days ago and still had the same reading. I went to Starbucks and picked up used ground coffee and put a hand full around the blueberry plants and still read 7 on the ph scale. Am I doing something wrong or is that ph meter not functioning correctly? I planted these plants less than 2 weeks ago so I'm not sure if it takes time for the ph to go down. Please let me know if I'm missing anything. Thanks

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Comments (10)

Ike Stewart
7 years ago
My first suggestion is to get a pH test kit with the little capsules of powder to test the soil. These typically cost less than $8 (Rapidtest 1612) and contain enough capsules to perform 10 tests
Sal73-Ireland
7 years ago
Sulfur takes a good few months to lower ph. Coffee grounds has a ph of about 7 although. In pots and raised beds I use a mix of fine barks and peat moss with added perlite for drainage and aeration. Generic garden compost has lime which blues hate , ericaceous compost is what you should have used in the mix. Iron sulfates also reduce ph and it reacts with soil in about 2 weeks but the effect doesn't last as long as sulfur thou.
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Pine and Cedar shavings and Pine Needles are not going to significantly affect your soils pH although enough organic matter in your soil will aid in buffering the plants and soil. Start your process with a good, reliable soil test and determine what your current soil pH is and that will aid you in deciding what needs to be done to grow those blueberries. You may well be better off putting your new plants in large pots for a year because it will take some time for the soil where they would go to change to provide the environment they need. Around here the soil is ideal for blueberries because the normally high water table creates anaerobic soil conditions that help make the soil pH ideal and provides sufficient moisture for them and low levels of magnesium help too. Here is a link that might be useful: Montana State University CES
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I grow them in pots and gather rain water for their water. To help lower the ph, I grab some pine needles from where ever and just cut them into smaller pieces and use them as mulch on top. A nice thick layer so it will keep in the moisture and as it decomposes and the water passes through, the ph will lower. At least that's what I'm hoping. This is my first time growing them but I have done some research.
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I grow blueberries both in the ground in raised beds (5 plants in the ground for five years) and in sturdy black plastic plant containers (5 plants in 4 to 7 gallon containers)--that I picked up cheap from a local nursery. Two years ago, I harvested over four gallons of blueberries. Last summer the container plants were a bit of a bust as a late 90 plus heat wave after I'd cut the watering back resulted in the container plants having a very poor crop, but I still harvested nearly four gallons of berries from the plants in the raised beds. They are picked and put into gallon freezer bags and popped into the chest freezer. I don't even wash them, as I use no pesticides on them. I removed my clay soil in 2'x2'x15" deep sections and built the beds up to about six inches above ground level with a mix of 3 parts sphagnum peat moss, 1 part leaf compost my town produces, and 1 part of the clay topsoil. I reused the rest of the clay in another part of my garden. The container mix is simpler: 2 parts sphagnum peat, 1 part leaf compost. The beds have not needed additional soil or peat in five years. I mulch the beds with pine needles (not for the acidity as they don't actually contribute any, but for the fact they contain no weed seeds to speak of). I use bark mulch as a mulch in the containers--it stops squirrels from digging in them and weeds from growing. I use drip irrigation with city water at a pH of about 6.5 or so, and fertilize with Ammonium sulfate every spring, which also keeps the acidity level up. Fafard makes a sphagnum peat moss based acidic soil mix, so that's an option if you can get past the sphagnum peat moss issue. If you're only growing enough blueberries for you and your family, you are not really going to need a lot of the stuff. It's worth noting that for every person who thinks sphagnum peat moss is not a renewable resource, there's likely another who thinks the opposite is true. Here's what I know: In the US, our ubiquitous Canadian sphagnum peat moss comes from a country that has a lot of it and only harvests a small amount of it, and reseeds the harvested areas with ... sphagnum peat moss, which in the university greenhouse collection I help maintain grows quite quickly--I frequently have to cut it back to keep it from overwhelming our carnivorous plants that grow with it. In North American bogs, the moss grows several or more inches a year. The harvested bogs won't be replenished soon, but they aren't exactly turned into parking lots either. Then too, the harvesting process is not very carbon intensive in the scheme of things. You can read more about this perspective on the topic here: http://www.theecologist.org/blogs_and_comments/commentators/other_comments/1780209/the_truth_about_peat_moss.html and here: https://garden.org/urbangardening/?page=august_peat
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Al's 5-1-1 mix, which you've no doubt seen reference to in this forum, is ideal for berries of all types. The ingredient list is very simple -- five parts pine bark fines, one part peat, and one part perlite. For raspberries and blackberries, you would also add one tablespoon of lime per gallon to raise the pH, but you should leave out the lime when growing blueberries. In zone 6B, you more than likely will have no trouble overwintering Northern Highbush, Half High, or any of the more northerly adapted Rabbiteye or Southern Highbush blueberry varieties without protection. Nonetheless, it never hurts to add an insulation layer of mulch, leaves, etc. around the pots as a precaution. As for blueberry pot size, you can start as small as three to five gallons (depending on the size and age of the bush when you purchase it), but, long term, you'll get better results with a pot in the 10 to 15 gallon range. You can certainly go bigger, especially with a vigorous rabbiteye variety, but that's not essential.
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Georgia Zone 8a
7 years ago
Another thought:

I planted my blues in a mix of peat, my own compost, and some sand.

My pH meter at the time showed about 5.5. I incorporated a little sulfur into the mix to maybe get the pH down a little further.

A few months go by, and my blueberries don't look so good.

I re-test soil pH and it's up to 7!

Did some research, and my irrigation water is the problem. It's just city water from the tap, but the pH is about 7.5 and it's loaded with bicarbonate which will send the pH screaming through the ceiling.

Purchased some acid to help acidify the water before it goes on the blueberries. We'll see how it goes.
Jason (Zone 10b, San Diego)
7 years ago
Much easier to control pH level in pots. I killed a very nice blueberry bush after I transplanted it from a pot into the ground. Thought I was doing it a favor. I've purchased another and will leave it in a pot.
Kevin Reilly
7 years ago
Inkfin, are you hand watering the BB's with the acid water or there is a way you do it via drip irrigation? Your plants look great seems like a lot to hand water though...
Jean
7 years ago
Potting mixes will naturally become more acidic as the components break down.
Kevin Reilly
7 years ago
Well, installing the drip will get you more free time! Saved me a lot when I finally put it in, was wondering how one would incorporate acid in to the mix on a drip system.
MrClint
7 years ago
"Please let me know if I'm missing anything"

Free time? That's a lot of work and effort for blueberries which are pretty easy. I don't own a pH meter and don't acidify my water, and my plants are doing great, some of my plants are six years old and counting in the same pots.

If you follow the BB directions at the Dave Wilson Nursery website from the beginning, and you fertilize with a good organic fertilizer (I use Dr Earth acid lovers blend) monthly, you should be fine. It works well for me and takes little effort.
Barrie, (Central PA, zone 6a)
7 years ago
A well rotted pine sawdust is a great and cheap mulch to keep blueberry soil acid but you need to get the pH down prior to planting or you will need frequent foliage spraying with chelated iron.

For your pH meter you should order buffer solutions of pH 4.0 and 7.0 to calibrate the meter whenever you use it. Still no gaurantee of accuracy but at least you should be closer than litmus paper.
steve bossie (3b) ME
7 years ago
to bring down ph quickly, some diluted vinegar and epsom salt will bring ph down long enough for the sulfur to kick in. don't remember the ratio i used. just google it. brought it down 2 numbers with one application!

Acidic soil for blueberries

Comments (10)

Ike Stewart

Sal73-Ireland

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Georgia Zone 8a

Jason (Zone 10b, San Diego)

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Jean

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