How to Increase Soil Acidity for Acid-Loving Plants

Will spreading pine needles around the base of my blueberry bushes increase the acidity of the soil? I know they like acid soil.

Answer: Soil is typically acidic, neutral or alkaline. To have acidic soil you need a pH lower than 7. (The scale is measured from 0 to 14 with a pH of 7 being neutral. Above 7 is alkaline, or basic.)

Unfortunately spreading pine needles around the base of your blueberry bushes will not increase the acidity of your soil. It is very important to have the right acidity in order to ensure your plants thrive. Here are a few methods that will help make your soil more acidic:

• Test soil: The first step is to test the acidity of your soil to see how much you have to lower the pH. You can find testing kits at most local gardening centers. For optimal success, blueberry bushes should have a pH around 4.5 to 5.5. Other acid-loving plants include rhododendrons, azaleas and hollies.
• Soil amendments: Once you know your pH you can determine if you need any additives to help obtain the level you desire. Remember: which additives and how much you use, as well as how and when you use them, will depend on how much lower your pH needs to be. Good pH-lowering amendments include: sphagnum peat moss*, elemental sulfate, sulfur and acidic fertilizers such as nitrogen fertilizer –make sure to read the label to confirm that it is acidic. You can also add aluminum sulfate and iron sulfate, which will quickly lower your pH, however you have to be cautious of applying these nutrients because they can be harmful to your plants. (Side note: If the leaves are yellowing and your pH is fine, then acidity most likely isn’t a problem, something else is. Your plant may have an iron deficiency, you could have issues with disease and/or pests or you are watering too much/too little.) Coffee grounds can help maintain a lower pH, too.
• Miscellaneous maintenance: In addition to the right soil, make sure you have a sunny location, water regularly, have lots of rich organic matter and have good drainage to further encourage your plants to thrive. You may also find that over time the pH of the soil begins to creep back up. You might continue to add amendments, or as an alternative you could try growing your blueberry bushes in large containers or raised beds/mounded soil so that you can completely control the soil mix and pH from day one. They are shallow rooted.

With the right acidity, maintenance, love and care you can help ensure that your acid-loving plants, such as blueberries, flourish beautifully.

*In recent years peat moss has fallen out of favor because harvesting it may contribute to global warming (carbon is released into the atmosphere) and it may not be a sustainable crop because it grows very slowly in peat bogs. Coir is a good alternative, though it is not quite as acidic.

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