How to Save Dying Roses in Summer Heat
This summer has been unusually hot, and many rose enthusiasts have noticed health issues with their roses. For example, the rose in the image below exhibits yellowing of new leaves, curled or dried-out terminal buds, and scorched tips and edges on older leaves, resembling fertilizer damage. What could be causing these symptoms?
Common causes of root damage in roses
When roses exhibit the above symptoms in summer, the underlying cause is usually root damage. Root damage is often caused by the following factors:
1. Drought and water shortage
In summer, high temperatures cause rapid water evaporation, especially for outdoor potted roses, whose soil tends to dry out easily. If watering is not timely, the rose’s fine roots may be damaged due to water shortage, and combined with intense sunlight, the leaves may become severely dehydrated, leading to scorched tips or edges, resembling symptoms of fertilizer damage.
Solutions:
- If the rose has dense foliage, it is best to water it once in the morning and once in the evening during summer to ensure the soil remains moist.
- However, this requires the potting soil to have good drainage to prevent waterlogging and root rot. If the soil drains poorly, watering should be done with caution.
2. Excessively high potting soil temperature
Most roses that encounter issues in summer are potted plants, as the smaller pots cause direct sunlight to rapidly increase the temperature of the pot walls. Since rose roots typically grow close to the pot walls, high temperatures can scald the root system, reducing its ability to absorb nutrients. Additionally, excessively high soil temperatures can lead to yellowing leaves and stunted growth.
Solutions:
- Move the potted plant to a shaded area or use a shade net to lower the temperature.
- Choose light-colored pots to reduce heat absorption.
3. Watering at midday
Watering roses at midday in summer is a major no-no, for two reasons:
- Large temperature difference: High-temperature potting soil coming into contact with cold water can shock the root system.
- Stifling heat and oxygen deprivation: After watering, soil moisture heats up under the intense sun, leaving the root system submerged in warm water, which can lead to oxygen deprivation and root rot.
Solutions:
- Water in the early morning or evening whenever possible.
- However, if the plant is severely dehydrated, watering at midday is necessary to prevent the rose from dying due to drought.
How to help roses survive the summer safely?
1. Shade and cool
This summer is exceptionally hot, so it is recommended to provide shade for roses or limit sunlight to the morning to reduce water evaporation and watering pressure.
2. Physical cooling
Water spraying: Around 4 PM, spray water on the pot walls and ground to lower the ambient temperature.
Adjust placement:
- Prioritize placing them on grass or soil, which are cooler than concrete surfaces.
- If grass is unavailable, use wooden flower stands to avoid ground heat radiation and improve ventilation.
3. Adjust Fertilization Strategy
During summer heatwaves, potted shrub roses should cease receiving quick-release fertilizers to prevent fertilizer damage causing black stems.
Summary: The key to summer rose care is maintaining healthy root systems. By implementing proper watering, shading for cooling, and adjusting management practices, roses can successfully endure the summer heat. We hope these suggestions help your roses thrive even in the hottest summer months!
