Sulphur or Acidic Fertilizer for Blueberries?

6 years ago

I have 2 blueberry plants: 1 is just a growing branch with a few flowers, and 1 that's already fruiting. I transferred them to my garden but then I realized my soil isn't acidic enough for them. I want them to live a long time so should I use sulphur to quickly lower the pH or can acidic fertilizer work just as well? Or should I repot them into acidic soil?

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Comments (6)

Barrie, (Central PA, zone 6a)
6 years ago
Your use of acidic fertilizer should be restricted to nutrient needs or you can kill the plants. Even Sulfur should not be applied in very large quantities if your soil requires a lot of adjusting. You could pot plants or you could just buy some chelated iron to spray on the plants 4-6 times through the growing season. That should keep plants from being iron deficient for the present until soil pH is sufficiently lowered that plants can draw up enough iron.
Adam B
6 years ago
You could also amend the soil around the plants with peat to help temporarily reduce the pH
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Wow... good point Al. I totally forgot about that. *whoosh* OW - Don't you mean.. lower to 6? If you have a way to directly measure the pH, then it doesn't really matter what kind of water you use. Just add the vinegar or acetic acid until you get the desired pH for the irrigation water. If you don't want to mess with the irrigation water, and you're okay with an imprecise change, you could use acidified cotton burr compost. It contains sulfur that is at least partially metabolized, and is often used as an acidifying soil amendment for Roses and Azaleas. It's commonly used both in the ground, and in containers. I don't know much about it, but you can find plenty of information online. I'm confused, are soil from your land in the containers? Or do you also want to try growing blueberries in the ground, and want to acidify the soil quickly? If you're using raised beds and adding a lot of new soil / amendments, most good nurseries sell an Azalea or Rose bedding mix that is fairly acidic. The quick fix is ammonium sulfate, but it's extremely hard for the non-professional to use properly, and is very detrimental to your soil biology. No amendment or product can really change your soil's pH permanently - you have to keep treating it at least every season.
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fruitnut: no problem, I am not even sure if blueberries are able to uptake heavy metals. I know they are indifferent to aluminum. Was just wondering about the runoff from the potted plants. About lead in IroniteÂyes I have heard that. I will not use it because of that fact. It might be safe for a lawn, but suppose next year you want to put a garden there, or use the clippings for mulch. Which leads me to olpeaÂs comment; yes most industrial grade agents contain some heavy metals and possible PBBÂect. Just how many PPM would depend on the manufacture, and with most industrial liquids made in China or Mexico where product safety is the last thing on their mindsÂÂah I would just pick up some sulfur as opposed to sending battery acid out for lab analysis. I mean hey, I am feeding this stuff to my kids and eating it myself....so cost plays second fiddle, to safety IMHO.
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These are interesting further comments! Thanks! They have made me think & now have more questions (sorry!). I'm still siting the bb before double potting in 1/2 wine barrels in next week. Since they don't look rootbound, will hold off actual repotting until dormancy as long as they look healthy. I haven't decided on a soil mix yet. I know Username's works & it looks like bb really like a lot of organic matter. My intuitive response would be to use this kind of soil mix (I get all excited abt. compost, earthworms, etc. although I haven't yet learned how to make compost in our vy. hot dry climate). My other choice would be a (very)simplified version of the fast-draining soil mixes discussed on the Container forum. Since I haven't been able to find the aggregate that forms an important part of those mixes, I experimented by just cutting either potting soil or amendment 50/50 with fine bark mulch. I then potted up my bareroots in it. It seemed so counterintuitive, but everything (so far) has thrived. It seems (for this hot, dry climate) to avoid having the outer soil area overheat & dry out while inner area remains damp to wet. Yes, it sure does need a lot of watering! It seems, however, to be much less tricky to water, i.e., you can water a bit early without danger of overwatering. I had lost a couple of rosebushes from overwatering here in the desert. Lest anyone reading this thinks abt. using same type of mix, let me point out that I still need to study the possible components of soil mixes & that problems w. the mix I have used may develop! Best to study to mixes others have used successfully over longer period of time. Username, do you think it would be necessary to repot bb using mix you described in year--couple years, i.e., would soil start to compact? If anyone would like to suggest alternatives to peat moss which they have used, I'd love to consider them. Kimmsr, would you mean leaves which are then composted? I ought to have quite a few of them when my espaliered pear and apple trees have grown a bit. Nandina, thanks!! Sunshine Blue sounds like a dandy--it's on my list for next year. You are right, the name of the game with the climate here is experiment! Squarefooterg, That's interesting! How are the ground citrus peels used? Thank you all!
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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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Ike Stewart
6 years ago
I guess the first question is did you amend the soil in the planting hole, mixing in peat with pine bark fines along with the native soil can go a long way in managing growing in soil conditions that have a pH above the ideal range for blueberries. The second question is how high is the pH of your native soil? Are we talking 6.0, 7.0 7.5, ...?

If the native soil is over about 6.0 you really should adjust the soil over a period of a year or more before putting the blueberries in ground. Sulfur is a not directly highly acidic, it must be broken down over time by bacteria to form Sulfuric Acid. Some types of acidic fertilizers are faster acting in their acidification of the soil, but even here too fast of pH change is bad for the plants. This leaves you with drip acification of irrigation water, which requires careful control and monitoring to keep the pH in the correct range.
Paul Menten
5 years ago
last modified: 5 years ago
Sulfur kills fungi and I believe that blueberries want fungi in their root system. So don’t use sulfur. I would try mulching underneath the blueberry plants with a very heavy layer of woody mulch.

I had good luck with Pineneedles and woodchips from my chipper shredder.
gardengal48 (PNW Z8/9)
5 years ago
Mulch will do nothing to contribute to soil pH one way or the other. That it has any sort of impact on soil pH is a gardening myth. And applications of garden sulfur IS the recommended method to lower soil pH but it takes time to work (several months) and may be inadequate for the purpose if current soil pH is too high. And will also be only a temporary fix....the soil will tend to revert to its natural pH eventually.

To best accommodate plants that require significantly acidic soils - like blueberries - in soils that are on the higher end of the range, it is suggested to grow them in containers or raised beds where the soil can be tailored to meet their needs. Acidic fertilizers will help to maintain the proper level of acidity while providing nutrients but they won't make any dramatic change to existing soil pH.
Paul Menten
5 years ago
last modified: 5 years ago
Regarding the role of organic matter and pH; while it may be true that mulch does not alter pH much, that is not its role in soil. OM acts as a buffer, allowing chemical reactions that would not otherwise happen because of pH.

Another role of OM in soil is to support fungi. Fungi will feed plant roots Phosphorus. Sulfur is a fungicide. No to Sulfur, yes to lots of woody mulch.

edit: High pH is characteristic of clay soil. Consider amending the soil by adding silt and sand, which are acidic.

Sulphur or Acidic Fertilizer for Blueberries?

Comments (6)

Barrie, (Central PA, zone 6a)

Adam B

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Ike Stewart

Paul Menten

gardengal48 (PNW Z8/9)

Paul Menten

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