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Sulphur or Acidic Fertilizer for Blueberries?

Suzanne Zone 10b
2 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?

Comments (6)

  • Barrie, (Central PA, zone 6a)
    2 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
    2 years ago

    You could also amend the soil around the plants with peat to help temporarily reduce the pH

  • Ike Stewart
    2 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
    2 years ago
    last modified: 2 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)
    2 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
    2 years ago
    last modified: 2 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.

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