davis:

I use sulfuric acid. Here's why. Vinegar is an organic acid. It ties up the bicarbonate anions in an organic complex that is short lived. When the soil organisms break down the organic complex, as they will before long, the offending bicarbonate anion is released and the pH returns to higher levels. This all equals no lasting effect on the pH of the blueberries root environment.

Sulfuric acid reacts with bicarbonate to form gypsum. This is stable and pH neutral. Thus it permanently lowers soil pH.

At least this is what I have understood from others who's chemistry backgound is a little more recent than mine.

The Fruitnut

Thanks for the reply (though the chemistry is a little over my head!). Are you adding the sulfuric acid directly to the soil or to the water as you water? Where do you buy sulfuric acid (and is it dangerous)? I remember some discussions way back about using battery acid and about the extreme care that must be used with it! In fact, some chemists came on to recommend against using it by us "average" gardeners. The virtue of household vinegar is that it seems so safe.

Would using a regular water filter help get rid of the harmful PH levels (water hardness) for blueberries? Or do water filters also remove some of the good stuff from the water that plants need?

Is sulfuric acid the stuff that is used to make regular soil acidic and suitable for Blueberries?

Would adding sulfuric acid when watering Blueberries that are already planted in acidic (erincatious?) soil cause problems by lowering the PH level even more than required?

I've been watering my blueberries with tap water (and I live in a hard water area), I haven't noticed any damage yet though - but from now on I will use rain water.

Kranser.

Most people use sulphur (ammonium sulfate or a similar compound) to acidify their soil to make it more hospitible for blueberries. Well, most people who aren't growing professionally or who aren't trying to experiment. (we're a pretty experimental lot here, as are many gardeners after a time I suppose).

Appropriate materials to acidify your soil can be purchased at most good garden centers, nurseries and even depot type stores.

If your plants are growing well and the new leaves are not yellowed, or showing yellowing at the veins then your soil pH is likely ok. (A soil test is a good inexpensive thing to do at least once)

~Chills

Sulfuric acid is most easily purchased as automotive battery acid. Yes it is dangerous. But I haven't had any problems. Sulfuric acid is used by commercial growers in California who cann't wait a yr or two for sulfur to take effect. But they have special equipment for soil applications.

For the home gardener, use sulfur to acidify your soil. Sulfuric acid would have a place only when one must water a lot with hard water. A little hard water during a dry spell is unlikely to be a problem. I use mine only when I run out of rain water. It problably won't be a problem even then since I use sulfur once a yr in my potted soil.

My three plants(Southmoon, Star, and Santa Fe) have seldom given an indication of iron deficiency. But they are southern highbush and may be more tolerant of high pH than some varieties. In fact they are the survivors of six southern and six northern highbush I tried 4 yrs ago. They were the best adapted to my conditions. They outgrew the northerns by a wide margin.

The Fruitnut

Fruitnut, I'm curious. Would sulfur (not sulfuric acid) have the same effect of stabilizing soil pH at a lower level? I had the impression that it needed to be added periodically to maintain low pH. I'm in California with soil pH around 8 and hard water.

Rosefolly

Yeah, I'm wondering the same thing as Rosefolly. I'm in California in her zone--with alkaline soil and hard water. Unless we set up rain barrels, rain water isn't much of a solution for us--there is *no* rain from June through September, yet high temperatures require constant watering of the plants.

Rosefolly:

Yes, if you apply sulfur periodically, the soil pH will be reduced. However starting with a soil pH of 8, it is going to be a hard long struggle to achieve and maintain a soil pH suitable for blueberries. I'd go with pots in that case. If your soil pH is naturally below 7, it would be much easier to get below 5.5 with sulfur. Sulfur gives the same end result as sulfuric acid. You just have to wait months or yrs for the effect to show up.

If you have potted bb and need to water all summer with hard water, then I'd get the battery acid and learn how to use it safely. The battery acid I got was 33% sulfuric acid. I diluted it 9:1 water:acid. That gave me a stock solution of 3.3% acid. 900 ml of that is enough to lower the pH of 50 gal of my well water to 4.5 from ~8. All well water will be different. ALWAYS add the acid to a large quantity of cold water. Never water into acid. Wear safety googles and old clothes.

The Fruitnut

This is a great thread. Thank you for sharing the information. I hope to grow blueberries in the future and now I have a good idea of how to prepare the soil.

There are charts avaliable that tell you how much sulfur to add to lower the pH to a desireable level given starting pH and soil texture. These are approximate. A detailed soil test would help. Can you add too much sulfur? Probably yes but like someone else I've never heard anything about this actually occuring. Again, a periodic soil test would help avoid over acidifying the soil.

A water filter will not remove the carbonates from water. Reverse osmosis will. A water softener makes the water totally unuseable by plants.

Battery acid is dangerous but remember people work with it all the time in their cars.

The Fruitnut

I've actually already planted 8 blueberries in a raised bed in the ground, 7 southern highbush, 1 northern highbush. I dug in bales of peat and bales of bark nuggets, based on recommendations for a pot growing medium for blueberries here. To the remaining soil in this mixture I added sulfur to lower the pH. So far the blueberries are not showing any signs of chlorosis, though I do see a little stress from high heat and me not increasing the water quickly enough to compensate. My plan is to keep checking the pH regularly, and to add sulfur as needed.

I am seriously considering moving them next year if they fail to thrive where they are. I have two planting beds in my back patio, and I think it would be easier to control the pH there. It would be like growing them in pots, except they would actually be in the ground. Blueberries are pretty enough to ornament a patio, in my opinion. I have roses there now, but could move the roses elsewhere easily enough.

Rosefolly:

Don't move your blueberries as long as they look good. And keep us posted as to the results. Our soil here is pH about 7.6. But it doesn't have free lime in the top foot or two. So I think it could be ammended to grow blueberries. I'd try but we have way too many late spring freezes.

Lots of people will be interested in your results. Blueberry posts seem to stimulate more interest than any other fruit. Good luck!!

The Fruitnut

Fruitnut, have no fear. As long as the blueberries do well they can stay where they are. If however chlorosis shows up despite my best efforts, that is when I will move them to the more controlled environment.

Rosefolly

I can verify from long experience, 12 years, that adding 5% white vinegar to hard water will successfully lower pH, and enable the blueberry shrubs to grow and thrive, with no yellow leaves. I would prefer to use sulfuric acid, but it is not readily available where I live, so I use regular vinegar from the grocery store. Our shrubs are set out in highclay soil, amended with either peat moss or compost, and also granulated sulfur, aka soil sulfur.

eric, thanks for sharing. how often do you do this? I imagine you cannot water your plants with vinegar everyday.

I'd like to try this, being a little too nervous to use battery acid! How much vinegar do you add to a gallon of water?

I've been using the water from my dehumidifier, thinking that will not have any hard minerals. Is that a correct assumption?

Margie

Margie:

Water that has condensed on your dehumidfier is distilled water. It will have no minerals that will hurt blueberries. Same as rainwater.

The Fruitnut

What effect will mulching with coffee grounds have on pH? We have several roasters around and grounds are easy to come by in fairly large quantities.

Thanks!

Nate

yeehaw502, used coffee grounds have a pH of 6.8 to 7. They will do little to change the pH. But they are a good source of nitrogen. I use them in my blueberries for that reason. I use pine bark, peat and sulfur powder in my soil. I am thinking of using suluric acid in my irrigation system to lower the pH faster, until the sulfur kicks in and lowers the soil pH on it's own. I am wondering if the sulfuric acid will cause damage to the microorganisms that feed off of the sulfur?

Vinegar has a Ph of about 2.5. One gallon, about 8 lbs., of cider would drop 800 lbs. of neutral soil to a Ph of about 4.5. (i.e, diluting an acid by 100x raises its Ph by two points) Since a cubic foot of soil typically weighs about 80 lbs +- a gallon of vinegar would acidify about 10 cubic feet of soil, or 10 square feet to a depth of one foot to a Ph of about 4.5. Therefore one gallon of vinegar would acidify about 3.3 feet of a 3' wide row of neutral soil. If the soil was already somewhat acidic, I would start with about 1/2 gallon per 3' of row.

Please note that although a desirable blueberry Ph range of about 4.0-to 5.0 appears to be a narrow range, it is actually a 10x range of acidity, so even if your calculation are off by a substantial amount, you should still end up within the acceptable Ph range. Each .3 change in the Ph roughly doubles or halves the acidity/alkalinity. A .6 point change roughly quadrupoles the acidity/alkalinity. A .9 Ph change changes the acidity/alkalinity by about 8x.

The acid ions in the vinegar (or battery acid) will bond with the clay particles and/or humus and not leach out to any degree. That is why soils in the eastern US are usually acidic, even in soils of limestone origin. Over time, the alkaline ions leach out of the soil leaving the acidic ions bound to the soil particles.

Although this is a very outdated/stale posting, it is important to note that blueberries do not require highly acidic soil to grow and produce well. That is pretty much a gardening myth! I live in area of very high blueberry production, both commercially grown berries and also the largest wholesale grower of blueberry plants in the country, supplying both retail nurseries and home gardeners. There is a large, established blueberry farm just down the street from me.

Native soils here are acidic but only slightly so....typically right around 6.0-6.3. And yet bueberries thrive here with no additional amending to further acidify the soil. Too much attention is devoted to supplying just the right pH to grow these plants when the emphasis should be on adequate soil fertility and sufficient water. LIke most plants, blueberries will thrive in a relatively wide range of soil pH. As long as you target towards 6.0 or lower you should be fine. But even slightly higher will not be a big handicap.

Just to add to this last comment, some varsities of blueberries are more tolerant to pH and other variations than others. In my region both Southern Highbush, and Rabbiteye blueberry varieties are grown, and out the the two general types the Rabbiteyes are far more hardy, not just in their accepted pH range, but in their need for irrigation and other conditions. I have 2 mature 30+ year unknown Rabbiteye blueberry bushes that went for over 10 years (maybe 15) with no attention at all that are still productive, though pruning and fertilizing the last few years have done wonders to improving their productivity. The unaugmented native soil pH here is about 5.7 , and is a fine sandy loam soil that is generally low to very low major nutrients, only iron is high.

Every year,we cut the boughs off our Christmas tree and place all around our blueberry bushes.. we get berries the size of