Is humidity a significant factor in growing lavender successfully?

Yes, humidity is a very significant factor in growing lavender successfully. In fact, for many gardeners, especially those in regions outside of its native Mediterranean climate, managing humidity is one of the most critical aspects of lavender care.

Here's why:

1. Fungal Diseases: Lavender's native environment is typically hot and dry. It evolved to thrive in low-humidity conditions. When exposed to prolonged high humidity, especially combined with heat, lavender becomes highly susceptible to various fungal diseases like:

   • Powdery Mildew: A white, powdery growth on leaves.

   • Botrytis (Gray Mold): Causes brown, decaying spots on leaves and flowers.

   • Root Rot: The most common killer of lavender. High humidity often goes hand-in-hand with insufficient soil drainage, creating constantly wet conditions around the roots which leads to fungal decay.

2. Reduced Air Circulation: High humidity exacerbates problems when air circulation around the plants is poor. Moisture sits on the leaves and within the dense foliage, creating an ideal breeding ground for fungi.

3. Impact on Plant Health and Flavor: While lavender can survive in more humid climates, it may not thrive as vigorously, produce as many blooms, or have as concentrated a fragrance and flavor (especially for culinary varieties). The stress from humidity can weaken the plant.

Strategies for Growing Lavender in Humid Climates:

If you live in a humid area (like many parts of the southeastern U.S. or coastal regions), successful lavender cultivation requires extra care:

• Choose Humidity-Tolerant Varieties:

  • Lavandins (Lavandula x intermedia): Hybrids like 'Phenomenal' and 'Grosso' are often more robust and show better tolerance to heat and humidity than pure English lavenders. 'Phenomenal' is particularly noted for its resilience.

  • Spanish Lavender (Lavandula stoechas): Some varieties are more tolerant of heat and humidity, making them a good choice for southern regions.

  • French Lavender (Lavandula dentata): Also exhibits some heat and humidity tolerance.

• Excellent Drainage is Non-Negotiable: This is paramount in any climate, but especially in humid ones.

  • Amend Soil: Incorporate plenty of grit, sand, or small gravel into heavy clay soils to improve drainage.

  • Raised Beds or Mounds: Planting lavender in raised beds or on small mounds helps ensure water drains away quickly from the root crown.

  • Containers: Growing in terracotta pots (which allow for good airflow through the sides) with a very gritty, fast-draining potting mix is often the best strategy in humid areas, as it offers maximum control over drainage and moisture.

• Maximize Air Circulation:

  • Spacing: Plant lavender with ample space between individual plants to allow for good airflow. Don't crowd them.

  • Pruning: Regular pruning helps maintain an open, airy structure, which improves air circulation through the plant.

• Watering Practices:

  • Infrequent, Deep Watering: Once established, lavender is drought-tolerant. Allow the soil to dry out completely between waterings.

  • Avoid Overhead Watering: Water at the base of the plant using drip irrigation or a soaker hose, rather than overhead, which leaves foliage wet. This is crucial in humid environments.

• Mulch Wisely: Use inorganic mulches like pea gravel or small stones instead of organic mulches (like wood chips or straw) which can hold moisture and promote fungal growth around the base of the plant.

In summary, while lavender can be grown in moderately humid conditions with careful management, low humidity is inherently the ideal climate for this plant, significantly reducing the risk of common diseases and promoting overall health and vigor.

Lavender Farm in Door County Wisconsin. You can buy lavender products online at islandlavender.com