Thanks, Al. I just may experiment with this method with a couple of my containers and see what happens. Interestingly, the EarthBox people sanction the one-time addition of a small amount of hydrated lime added directly to the water reservoir as an emergency correction for tomato BER (I forgot the actual amount, it's in the EarthBox forums). They note that this is not an immediate fix but should help within a week or two. I tried it last year with some tomatoes in real EBs that had terrible midseason BER with the first fruits set (I did add the suggested amount of dolomite lime at planting, but it's common to get BER in my EBs, especially early on). The problem did go away within a couple of weeks of adding the lime to water, and the plants did just fine. It is impossible to know whether the lime treatment fixed the BER or whether it went away on its own, as it often does. But it didn't seem to hurt, anyway. Eric

The closest large seller of farm fertilizer is about 50 mi south of here, but I can arrange a stop there on my way to getting pastured meat in the Fall. There used to be one not 15 miles from here but no more. As some of you know, my pH=9.2 water coupled with pH=7.7 soil can be a handful. Only grapes need it in the orchard, and I give it to tomatoes and potatoes in the garden, and of course I add more organic matter than most (21% OM in the garden). Anyhow, IIRC in late 2011 one 50lb bag of sulfur was $20. I had to sign a declaration that it and the rest of the stuff was intended for food production not to pay the sales tax. If you have relatively large holdings, it pays to go to such a place. A single 50 lbs urea bag allows many years of fertilization between trips. The 2011 trip was concomitant to starting the orchard in horrible, lifeless, compacted P=7ppm soil, so I got 25lbs of superP, 100 lbs of sulfur, microminerals solution to be added in the sprayer, and 50lbs of urea which will take me to 2020 or so. I have now added over 30 tons of wood chips to the orchard, and the soil is less horrible, but to start it you have to do a first amending.

Going with the second post - pH in container plantings is not really an issue. The vast majority of potting soils are pretty close to neutral and the frequency of the fertilizing required plus frequent watering with extremely variable pH tap water pretty much makes this issue moot. pH can be adjusted/altered with virtually every watering! But doesn't really make much difference anyway given nutrient availability. Al at the Container Gardening forum is pretty much considered the fountain of all knowledge re: container gardening :-) It's pretty hard to find fault with anything he has to say.

@Jonah Henry - you have a point and an implied question I can't answer - you wrote "I don't think garden DL is 7 pH. I think it's higher than that at least 8." The one bit that jumped back into my head just now is that pH is defined as the concentration of hydrogen ions in a solution - in other words, it doesn't generally make sense to talk about the pH of a solid, like powdered dolomite lime. (You can find colourful analogies about this, eg pH of a solid makes as much sense as the length of a liquid...) So I think that if DL isn't / doesn't tend to be soluble above 6.5, as your texts refer to, perhaps it would be fair to say it's not relevant what the hypothetical pH is - save that the hypothetical or latent higher pH might be the buffering capacity you referred to, but doesn't mean it will become alkaline with excess DL. That said, I know enough chemistry to know this is way above my knowledge level and there are probably a million different ways my phrasing of this is wrong. Relevant here, for example, that highly reactive powders may not have a pH per se (because solids) but doesn't mean they won't react to (go into solution in) air or moisture in air or water of any kind that they contact. Or more generally that how / when they'll be soluble is not a simple question. (And that's before even asking the question about gases or solids that act like liquids in certain respects/conditions but let's hope eg supercritical steam or magma are not conditions one will encounter in container gardening).