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I've got 3 Jersey blueberry shrubs planted in my greenhouse, in the ground. They are 3' wide and 2' tall, producing berries nicely. They'll be bigger in the years to come but this year I planted squash in the soil between them that are very healthy. The blueberries are showing signs of nutrient deficiency (rosy colored leaves) I'd like to lower the pH (it is 7 in this bed, the rest of my beds are 6.5) just around the blueberries themselves. What would be some ways of doing this? Can I use a very diluted amount of vinegar. If I lower the pH to 6.5 just for this year will that be O.K.? What is a good compromise that satisfies both plants? What other vegetables enjoy acidic soil?

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    Out of curiosity, why do you want the amendment so localised if you're expecting further growth around the blueberries in coming years? Also, I think squash usually do well down to about 6.0 pH, so if you're just going for a short term/quick amendment that shouldn't be a concern. – Laughing_Jack Jul 23 '14 at 20:32
  • Localized just for this season. If squash do well down to 6.0 then I think this answers most of my question. What can I use to lower the pH temporarily that is simple, I've got around the house. Living on a tight budget...how about vinegar? Thanks, Jack! – stormy Jul 23 '14 at 20:50
  • My blueberries love a mulch of pine needles and used coffee grounds. Peat moss works well too. – WebChemist Jul 24 '14 at 5:12
  • I've got plenty of pine needles. How long does it take to compost pine needles, I'd rather not use non-decomposed organic matter. But I could get started decomposing them? Thanks, I'll let you know what I find out! – stormy Jul 25 '14 at 21:37
  • Guess that depends on your climate, watering, local bacteria and fungi, etc. I noticed mine where showing signs of pH induced nutrient deficiency last year, so I gave them elemental sulfur for a quick fix then threw down few handfuls of dry needles left over from our christmas tree. That was over a year ago and the top layer still hasnt decomposed but some of the underlayer has, hard to tell exactly how much. But I haven't had to do much since but water and the occasional liqiud fish fertilizer. The thick layer of whole needles does a decent job of weed supression too. – WebChemist Jul 27 '14 at 0:22
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The best way to decrease the pH of your soil is to add organic matter that the acid producing microbes like, though that also takes time. To increase the acidity in soil more quickly than that it's usually recommended that you add sulfur (elemental sulfur or a sulfate) or ammonium phosphate. Vinegar will change the pH, but it is a very short-lived benefit and you have to be careful that you don't overdo it. In particular, if you have water-starved plants and you add a lot of vinegar the plants will tend to suck up more vinegar than you want.

You might try to incorporate a combination of things so that your short-term problems are addressed while still adding the sulfur that would feed for medium term and organics for the longer term. Exactly what you do would be determined by the type of sulfur you have available and also what organics you can use. Consult the fertilisers to see how long their uptake is to determine when to stop using vinegar. For organics, I usually just plan on 1 year before they start affecting my soil.

The concentration that I've seen around for vinegar is about 2 Tbsp per gallon of water when you water the plants, though you might want to go with a slightly weaker concentration initially. If you have a home tester for pH, even one that doesn't normally give you 'correct' results, it would be beneficial to test the soil just after watering with just water, then just after watering with the vinegar added the next time. You'll be looking for the change here in pH, not the absolute number, so most any tester that measures it at all would be helpful.

  • This is great Jack! I've got pumice/sand for soil. This is my first year and have added quite a bit of compost to the soil, microbes and mycorrhizae. The soil will be better/different next year. I keep compost on top of the soil and it amazing how the microbes are going through it! My plants are never starved for water. I have to water almost every day! I have a great tester...cost over $300 bucks years ago. I want to try the vinegar, perhaps half of what you recommend to start. Your answer is great, thanks! – stormy Jul 24 '14 at 1:56

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