Hi
@RealOAK5! This could be: 1/ Roots related issue: root-bound, root-rot. 2/ Calcium deficiency. 3/ Manganese deficiency. The last two options could come from a wrong pH, are you applying the optimal pH range for your plants (6.0~6.5)? This can also come from a nutrient-lockout / salt-buildup. Do you check the EC of your feedings? How often do you feed and how often do you give plain pH'd water? Now for the 1st option about roots, is your garden deep enough for roots to spread? Do you have a concrete slab under the medium, if so at what depth? Let's investigate all together and I'm confident we will find a solution. Happy growing 👊