Lowering pH per Soil test results

Asked October 31, 2019, 6:25 PM EDT

I planted several acid loving shrubs (eg, Camellia, Osmanthus, Pieris) in two garden beds a few weeks ago. I just got back soil test results from U of Del. showing very high pH levels (6.8 and 7.0 for the 2 beds). Is it okay to add sulfur to lower the pH now, or is it better to wait until Spring?

Montgomery County Maryland

4 Responses

Those plants would be most happy growing in a soil with a pH between roughly 5 and 6.
This page from Cornell does a good job of explaining how best to adjust the pH to a lower number. Sulfur takes longer than aluminum sulfate or ammonium sulfate.
See here: https://hgic.clemson.edu/factsheet/changing-the-ph-of-your-soil/


My question was about timing- can I add it now or need to wait til spring

My question was about timing- can I add it now or need to wait til spring

Hi- we apologize for not answering your question completely.

  • Apply sulfur now as it can take months to lower the soil pH.
  • We recommend that you use either elemental sulfur ("flowers of sulfur") or iron sulfate, or a combination of the two products. Both can be found in most garden centers and large hardware/home improvement stores. Please use the information (#5) on this Penn State web page to determine the amount to apply: https://agsci.psu.edu/aasl/online-report/home-garden
  • We recommend that you not use aluminum sulfate or ammonium sulfate to lower soil pH. Ammonium sulfate is an excellent fertilizer and it will help lower soil pH. However, it should be applied in spring based on soil test results and recommendations.