Coffee Grounds and Pine Needles for Blueberries

Question

May I ask a question about acidifying soil? We have 52 blueberry bushes planted in our nice Indiana clay loam, which has a pH of 6-6.5. Blueberries like it from 4.5-5. I have read that coffee grounds are really low in pH and would like to use them with our pine needles to organically acidify the soil. (The pH of pine needles is 6-6.5). My question is, is it better to mix the coffee grounds and pine needles in a compost pile and let it decompose first, or can I place them both directly on the blueberries? Some folks say that in the process of decomposing, the grounds and needles can actually leach nitrogen from the soil. Others say that in a compost pile, coffee grounds lose their low pH. Are the coffee grounds and pine needles sufficient in themselves to feed the blueberries, or do we need a real fertilizer to do that job? Any light you can shed would be greatly appreciated.

Answer 1

It should be ok to place the coffee grounds and pine needles around the area as is, no need to compost first as they will not harm the plants and will eventually break down into the soil. These articles should help you with that: https://www.gardeningknowhow.com/composting/ingredients/coffee-grounds-gardening.htm , https://www.gardeningknowhow.com/edible/fruits/blueberries/lower-soil-ph-blueberries.htm