Why should I avoid summer shrub planting?
Written by
Michael Sullivan
Reviewed by
Prof. Martin Thorne, Ph.D.Planting during the summer causes extreme stress for shrubs that can be lethal. When temperatures exceed 85°F (29 °C), the soil becomes hotter than even the most resilient roots can withstand. Plants then enter a survival mode, maintaining their foliage while abandoning further root development. This basic stress response kills chances for long-term establishment.
Heat Mitigation
- Plant during cool morning hours before 10am
- Use shade cloth (50% density) for first 3 weeks
- Apply reflective mulch to lower soil temperature
Hydration Management
- Water at 6am, 12pm, and 5pm during heat waves
- Use drip irrigation with timer controls
- Add water-absorbing polymers to root zone
Root Protection
- Soak rootballs in cool water before planting
- Apply anti-transpirant sprays to reduce moisture loss
- Avoid fertilizer to prevent salt burn
Root burn takes place once soil temperatures rise above 90°F (32°C). That means it literally bakes tender root hairs that are responsible for water uptake. Damaged, those roots will not recover. For my thermometer readings, unshaded soil was taking readings of 100°F (38°C) on 80°F (27°C) days.
Plants make a survival decision under heat stress. They reallocate cellular energy investment in root development to ensure survival and maintain foliage health. This leads to a death spiral, where inadequate roots cannot sustain the foliage, and the plant ultimately collapses. I've seen hydrangeas look perfectly fine for weeks on end, but they dropped suddenly, except for one afternoon.
In the summer, the watering requirements become unsustainable. New plantings and shrubs require 3-5 gallons a day and often require several waterings. Even then, surface-ground dry content, seepage, and evaporation mean it never quite saturates deeply. My rain gauge regularly shows that 80% of the morning water has evaporated by noon on extremely hot days.
Container crops have it slightly better, but still struggle. The root system is more established and can handle stress marginally better, but it still requires constant attention and care. I saved hedge roses that were in pots by soaking them twice a day, but they still were stunted for years afterward.
Read the full article: When to Plant Shrubs: Complete Guide
