I've read that oak leaves have some acidifying properties either as they break down or after composting. Not sure which one it is. I'm sure there is more info on the net about this subject. Most blues like 5.5 to 4.5 pH but don't if oak leafs alone will achieve such a low pH. It's worth look though.

It seems like unamended soils in my part of North Carolina generally have a pH between 5 and 6, so some marginally effective amendments might be sufficient here. One of the reasons I'm asking is because I've mostly just grown rabbiteye types so far, but I'm interested in highbush varieties for the potential to begin the season 2+ weeks earlier than the earliest rabbiteye cultivars. From what I understand they're not as well adapted to my conditions, though, and I think they're also less tolerant of slightly higher pH conditions that might not bother rabbiteyes, so it seems like I'm going to need to be more careful about pH if I'm going to successfully expand into highbush types.

Floyd,

It is very hard to answer your question because it really depends on your water. While you may never get the PH as low as you want the plants may grow fine even without a soil PH of 5 as long as you use rain water on the bushes or are lucky enough to have low bicarbonate well water. If on the other hand your well water is hard and rich in bicarbonates it won't matter what organics you use your PH will be too high and the bushes will suffer.

If you could locate an area where there is a heavy layer of volcanic ash, and if you could dig up and remove the ash legally, then you could use this free material as a soil amendment to lower pH. Agricultural sulfur, in 50 lb bags, was being sold at 45 cents/pound at the farmer's co-op in Marshall, Wisconsin, in 2012. The sulfur is from Canada, where it is separated from natural gas, as sulfur dioxide, and then reduced to sulfur. So it is a recycled material, in that sense. Many people have successfully fertilized blueberry shrubs with composted manure, but some caution is needed-too much nitrogen fertilizer will damage the shrubs.

Floyd,

Like you, I wanted to start picking berries before my Climax rabbiteyes were ripe, so I tried Spartan and O'Neal. The Spartan were not happy with my soil, and died in a few years. The O'Neal did great in the same soil as my rabbiteyes, and ripened a week or so before the Spartan, and about 3 weeks before Climax.

Benny

There is a sulphur hot spring the wife likes to go to for health & relaxation - I gave a gallon of that to our blueberry and it responded very well.

Coffee grounds and pine needles may help somewhat.

Also, as a general principle, more organic matter will buffer the effects of ph that is either too high or too low for most plants.

Coffee grounds are an interesting possibility, not that they're "local," but I potentially have access to large quantities of coffee grounds. Can anyone tell me (or point me to) more about coffee grounds as a fertilizer/amendment?

Floyd,

The coffee grounds are great but they won't help to acidify your soil much. While coffee is quite acidic most of that is extracted in the brewing process. The coffee from drip brewing will retain the most acid and from good espresso machines will have almost no acid left. In any event if your water is high in bicarbonates it won't matter as your PH will rise.

The other problem with coffee grounds is the acid is an organic acid so the bacteria in the soil will consume it and it disappears. The grounds are still good for the soil though.

Here you can get Tiger 90 pelleted sulfur 50 pounds for $10. That would be from Helena chemical which is a nationwide company. Look them up and see if you have an outlet near you.

Bamboo, thanks very much for the advice, but I wouldn't say I even have a problem to correct. I'm mainly just wanting to just deepen my understanding, particularly of non-purchased options for soil acidification, and in any case, dollar costs really aren't my concern at all. Not to hijack my own thread and make it too much about my own personal circumstances (as opposed to the more general questions), but I'm very satisfied with how my rabbiteyes are doing, and if the pH isn't in the ideal range for them, it's very close, and so long as they keep performing as well as they have been I probably won't even bother to check. I will probably check before I buy any more highbush plants. (I did receive two northern highbush plants randomly several years ago, and they didn't survive, but a number of factors, including transplanting due to a move, could have played into that.) Also, although I watered a fair bit the first year or two, I don't hardly water my blueberries at all any more. I may have only watered them two or three times this past year (albeit an overall wet growing season.) If bicarbonates were a problem, I could easily use rainwater for all my blueberry watering, but as little as I've been watering I don't know if it would even matter. What about coffee grounds, though, even if not for the purpose of acidification? Would it be good just to put them around the plants like mulch? Can I overdo it?

Yukkuri made a real good point about organic matter.....

I reacall from watching the Back to Eden film that his blueberries were doing quite well without concern for ph factor. I put the link below. If you have not seen how he prunes his apples, it really is amazing.
Carol

Here is a link that might be useful: Back to Eden film

Floyd,

If you are only watering a few times a year the water won't matter, rain water is best. The coffee grounds are great....you could put them around the plants 6" deep if you want, wish I could get them delivered by the truckload. BB also love sawdust so if you have a mill near you most times the chips are free for the taking.

Far as the organics......my plants get 10" of wood chips a year.....that is how fast they break down in the subtropics. While the chips are great they don't buffer the PH. Some people that say oh my plants do fine being kept in PH 6.5 but they have never seen the massive difference of highbush BB kept at or near their ideal PH. The organics keep the roots cool and moist but as far as the PH? They make little difference.

Floyd

The larger pieces of sawdust from a round blade work well, however the fine dust or pieces from a band saw mill will form a hard layer on top and water will not penetrate it.

Benny

I gave up on sawdust because bermuda grass seems to just love it, to root all in and through it really aggressively. I started using pine needles for mulch a couple years ago, and for me pine needles are worlds better than sawdust as a mulch. I suppose something like sawdust or coffee grounds could be put around the plants as an amendment and then pine needles could be put on top of that for a mulch, though.