Hydrangea Wilting Daily in Toronto: Heat Stress, Not Disease

Mophead hydrangeas in Toronto (Zone 6a) that shrivel by afternoon and recover by evening are showing heat-induced transpiration loss, not illness. The large leaves lose water faster than roots can replace it in afternoon sun.

Immediate Relief

• Ensure soil is uniformly moist (not soggy) at all times.
• Water deeply in early morning.
• Apply 3″ mulch to conserve moisture.

Nutrition

Feed with Miracid (acidic fertilizer) per label—hydrangeas love acidity. It also supplies phosphorus for flowers.

Long-Term

If the site gets >4 hours of hot afternoon sun, consider moving to a spot with morning sun only. Established plants tolerate more sun if roots stay cool and wet.

Daily wilt/recovery is common in summer; consistent moisture prevents damage.