Hydrangea Blooms Turning Green/Brown: Fertilizer and pH Issues

Hydrangeas bloomed pink/purple, then faded to green-yellow-brown after Holly-tone application. Leaves healthy but outgrowing blooms. Other side has smaller blooms hidden under leaves.

Diagnosis

• Excess nitrogen: Holly-tone may have too much N — promotes leaves over flowers. Use high P-K fertilizer (10-20-20 or 0-10-10) or triple phosphate — but too late this year.
• Color change: Not all hydrangeas turn blue with acidity. Those that do need much more acid than Holly-tone provides. Aluminum sulfate (4x expected amount) + acid fertilizer may work over a month.
• Hidden blooms: Likely same nitrogen issue — excessive foliage hides flowers.