Large hydrangea bush shrub growing in sunny summer garden covered with large pink mophead flowers in acid soil
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The Downsides To Growing Hydrangeas In Your Garden
They Won’t Bloom
Hydrangeas may fail to bloom due to improper pruning or excess nitrogen. Pruning old wood species at the wrong time can cut off the next season’s flowers.
For old wood varieties, only remove dead or sick limbs. Ensure the plant gets morning sun and afternoon shade to flower. Use an 8-16-6 fertilizer to prevent excess nitrogen.
No Change In Color
Changing soil pH to alter hydrangea flower color only works on bigleaf and mountain species. Lowering the pH makes them blue while raising it turns them pink.
Use sulfur or aluminum sulfate to lower pH and limestone or hydrated lime to raise it. If it doesn’t work, avoid altering soil alkalinity further to prevent problems.
Droopy Leaves
Hydrangea leaves often wilt in extreme heat. To avoid this, ensure they get morning sun and afternoon shade. Add a 2-3 inch mulch layer to retain soil moisture.
Water when the soil feels dry 1-2 inches deep. If only the flowers droop, reduce fertilizer, as too much nitrogen causes thin stalks that can't support large hydrangea blossoms.
Holes In Leaves
Caterpillars and Japanese beetles cause holes in hydrangea leaves. You can remove them by shaking the plant in the morning or treating it with neem oil.
Slugs also tend to bite the leaves. Prevent them by raking fallen leaves and using beer traps. Bury a tuna can with beer near your hydrangea to catch and remove slugs.
Brown Spotted Leaves
The spots indicate a fungal disease caused by the Cercospora hydrangea fungus. To prevent it, always water the base of the plant and avoid wetting the leaves.
Treating the plant with fungicide biweekly early in the spring will prevent spotted leaves. Choose a product that contains chlorothalonil, mancozeb, or thiophanate-methyl.