Why Are My Blueberry Leaves Turning Yellow?
The most common cause is soil pH that is too high. Blueberries need acidic soil (pH 4.5 to 5.5), and most Santa Cruz County garden soil sits between 6.0 and 7.0, which locks out iron and causes yellow leaves with green veins, a condition called iron chlorosis.
This is not actually an iron deficiency in the soil. The iron is there, but at higher pH levels, the plant's roots cannot absorb it. UC ANR's blueberry growing guide emphasizes that maintaining low pH is the single most important factor for healthy blueberry production. You can lower soil pH over time by working in sulfur (follow package rates, since over-application burns roots) and mulching heavily with acidic materials like pine needles or aged sawdust. For container blueberries, use an azalea/rhododendron potting mix, which is pre-acidified.
Other causes of yellow blueberry leaves include overwatering (blueberries want consistently moist but never waterlogged soil) and nitrogen deficiency. If the entire leaf turns pale yellow-green rather than showing green veins on yellow leaves, nitrogen is more likely the issue. Feed with an acid-forming fertilizer designed for blueberries or azaleas.
In coastal Santa Cruz, blueberries actually do well because they prefer mild summers and consistent moisture. The main stumbling block is always pH. Gardeners in the fog belt who grow blueberries in containers with acidified mix often have better results than those planting directly in the ground, where our naturally higher-pH soil fights you continuously.
This week: Test your blueberry soil pH with an inexpensive probe or test kit from any garden center. If it reads above 5.5, apply soil sulfur according to the package directions and mulch with pine needles.
Our free Troubleshooting Guide covers nutrient deficiency symptoms and soil correction strategies for common Santa Cruz garden problems.
