What is the best fertilizer to use for blueberry plants in the spring? Also how soon can I plan in soil that I used gypsun in to break down clay filled soil?
Marion County Oregon blueberries
Depending on whether you are using organic or synthetic options there are a lot of choices. You just want to make sure your fertilizer choice employs ammonium (not nitrate) as the preferred form of nitrogen. So a good synthetic source is ammonium sulfate, for instance.
Gypsum is an effective amendment for sodic soils (soils high in salts), but it does not alleviate compaction or improve structure in clay soils free of salts. Because of all our winter rain, soils in the Valley do not accumulate salts the way salts in eastern Oregon soils may do. In areas with sodic soils, gypsum (calcium sulfate) is effective at removing salt and building structure. The amendment of choice here is a disease and weed-free source of organic matter, like yard debris compost. You have added calcium and sulfate to the soil, mind, which may not be a bad thing.
I include a link to the OSU Extension publication "Growing blueberries in the home garden" for further information.