Tips for Keeping Dahlias Thriving When the Heat Is On – Bear Creek Farm

Understanding how to care for dahlias in both consistently hot climates and during temporary heat waves is essential to maintaining their health and beauty. Let’s explore strategies for each situation.

Living in the Hottest Place

For gardeners in regions where high temperatures are common, long-term planning and strategic maintenance are essential.

1. Site Selection and Shade Provision:

   • Strategic planting: In hot tropical climates, planting areas that provide natural afternoon shade are a good choice. Placing dahlias near tall plants or buildings can provide relief from the harsh midday sun.
   • Shade Cloth: A shade cloth to protect the dahlias during high temperatures is another way as it reduces the stress of the sun and prevents the heating of the leaves.

2. Irrigation and Soil Management:

   • Deep Watering: Establish a deep watering schedule to keep the roots moist. Watering early in the morning reduces evaporation and ensures that moisture reaches the roots.
   • Covering with holes: Spread a thick layer of organic mulch around the base of your dahlias to retain moisture and keep the soil cool. Mulch also helps suppress weeds that compete for water.

3. Earth Amendments:

   • Improving Soil Structure and Fertility: Improve your soil with organic matter to improve its structure, nutrients, and bacterial activity. Well-formed soil with a good organic content supports healthy roots and better water penetration, preventing root rot, a common problem in hot and humid conditions.

4. Nutrient Management:

   • Balanced Nutrition: Provide regular, balanced fertilization to support vigorous growth and flowering. Choose a low-nitrogen or no-nitrogen fertilizer to avoid overblooming without blooming.

5. Heat Tolerant Varieties:

   • Wide Selection: For dahlia growers in warmer states, choosing heat-tolerant varieties can make a big difference. These varieties are bred to withstand high temperatures and continue to bloom despite the heat. For more information on heat tolerant dahlia varieties, you can check out the Dahlia Society of Georgia.

Managing Temporary Heatwaves

When faced with an unexpected heatwave, immediate protective measures are essential.

1. Temporary Dimming:

   • Movable Shade Solutions: Use temporary structures such as garden umbrellas or portable shade cloths to protect dahlias during the hottest part of the day.
   • Natural Shade: If possible, move potted dahlias to shady areas until the heatwave passes.

2. Irrigation Increased:

   • Frequent Watering: During heat waves, increase the frequency of watering to keep the soil moist but not waterlogged. Watering in the morning and evening is very effective.
   • Misting: Lightly misting the foliage can help cool the plants and reduce heat stress. However, avoid misting in the sun to prevent leaf burn.

3. Monitoring and Care:

   • Check Soil Moisture: Regularly check soil moisture levels to avoid both drought stress and waterlogging. Adjust your watering schedule based on these observations.
   • Pest Monitoring: Heatwaves can make dahlias more susceptible to pests such as spiders. Keep a close eye on your plants and take action at the first signs of infection.

4. Emergency Measures:

   • Heatwave length: For short heatwaves, focus on keeping dahlias comfortable rather than making permanent changes. Temporary solutions are usually sufficient to overcome a short period of high temperatures.

Understanding Dahlia Growth and Stress

Interestingly, dahlias stop growing and may not bloom when temperatures reach 90 degrees Fahrenheit. Symptoms of heat stress include stunted flowers and susceptibility to pests and diseases. Despite this, it is important not to lose hope. When temperatures drop, dahlias usually begin to bloom.

Despite the opposition, dahlias grow best in the absence of light. The plant’s phytochromes detect darkness, stimulate the production of growth hormones and cause dahlias to grow when they need light. Maximum growth occurs before dawn, using stored glucose from photosynthesis as food. This scientific phenomenon emphasizes a beautiful metaphor for resilience—dahlias grow stronger in the dark, preparing for the light.

Closing the Gap: Consistency in Care

While strategies vary depending on whether you’re dealing with a persistent high fever or a short-term spike, some principles remain the same:

• General Monitoring: Always keep an eye on the condition of your dahlias, especially during extreme weather changes. Quick action can prevent small problems from becoming major problems.
• Adaptability: Be prepared to adjust your maintenance procedures as needed. Adaptability is the key to successful gardening, especially in variable environments.
• Information and Preparation: Understanding the specific needs of dahlias and staying informed about weather forecasts allows you to plan and react effectively.