Lowering Soil ph

Asked May 4, 2018, 3:36 PM EDT

Hi, I had my vegetable garden soil (raised bed) tested this year by the Univ. of Delaware. The soil ph is 7.3 I would like to lower that by about a unit for my tomato plants. I'm thinking of using elemental sulfur but am wondering how much to add as a side dressing in order to lower the ph. The tomatoes are about to be planted and I want to be careful not to burn the roots. Is elemental sulfur a good option or should I consider something else? Also how much should I add? Thanks very much, Lisa

Montgomery County Maryland

1 Response

Your soil pH at 7.3 would be fine for growing tomatoes. If you have been adding compost to your soil and there is a good amount of organic matter, you really don't need to apply a soil amendment at planting time. If, however, you do want to lower the pH, fall would be the best time to work sulfur into the soil. Use a combination of elemental sulfur and iron sulfate. Iron sulfate will cause pH to drop more quickly than elemental sulfur and should be applied according to the rate and directions on the product label. Avoid using aluminum sulfate because aluminum becomes more available with declining pH values and may lead to plant toxicity problems.