Seed and zonal geraniums are iron-efficient crops that are prone to iron/manganese toxicity when the media-pH gets too low. Once plants show toxicity symptoms of necrotic spots and marginal burn (Figure 1), the affected leaves do not completely heal. The only options become shipping lower-quality plants–to take additional time to produce healthy new growth that will cover the older damaged foliage–or throwing plants away.
Tips For Applying Flowable Lime
Tips for Applying Potassium Bicarbonate