Soil Compaction and Poor Drainage
Heavy, compacted clay soils or beds that pool water after rain can suffocate sunflower roots—leading to stunted growth or wilted foliage even on bright days. I tried planting along a low-lying border and watched water settle around my sunflowers after every storm, turning their base into a mini-pond!
Loosen the planting area to a depth of at least 12 inches, mixing in coarse sand, compost, or perlite to improve structure. Building raised beds or mounding soil into gentle hills also encourages excess water to drain away, while giving roots breathable air and fluffy texture to explore.