Blueberry Problems (Iron Chlorosis)

Our blueberries are not doing too well. After a little research I think they are suffering from Iron Chlorosis.

Blueberries are acid loving plants. They thrive in soil with a PH between 4 and 5. I tested the soil PH using a simple test with baking soda and vinegar with a result indicating the soil is neutral (PH around 7). We used peat moss and pine mulch when we planted them but it apparently was not enough to lower the soil PH enough for them.

Below are pictures of our blueberries. Notice the yellowing of the leaves - this is an indication of iron chlorosis. The yellow leaves could be an indication of nitrogen deficiency, but the results of the soil PH test lead me to believe it is iron chlorosis.

We will have to take more drastic measures to reduce our soil PH closer to 5. Luckily the vinegar test did not indicate that there was free lime in the soil (the vinegar would have fizzed when added to the soil if there was free lime in the soil). Free lime in the soil makes it even harder to lower the soil PH. The Colorado State University Extension CMG Garden Notes #222 Soil PH states [o]n soils with free lime, a gardener will not effectively lower the PH.

Considering the significant decrease in PH we are going to need to make, we are looking into using elemental sulfur, iron sulfate, or aluminum sulfate to lower the PH closer to 5. I do not think we could reduce the PH enough usingpine needles, pine bark, or peat moss without the help of elemental sulfur, iron sulfate, or aluminum sulfate.