Optimal Temperature and Storage Methods for Arum and Calla Lily Bulbs

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Arum lilies (Zantedeschia aethiopica) and Calla lilies (Zantedeschia spp.) are prized for their stunning flowers and lush foliage. To ensure successful growth and storage, it is crucial to understand the ideal temperature conditions and proper storage techniques for their bulbs. This comprehensive guide covers everything from greenhouse temperature management to best practices for storing bulbs during the dormant season, incorporating expert insights from various sources.

Temperature Management for Arum and Calla Lilies

Greenhouse Conditions

Proper temperature management in the greenhouse is essential for the healthy growth of Arum and Calla lilies.

  • Initial Growth Phase: After planting the tubers, maintain the greenhouse temperature between 62°F to 68°F (17°C to 20°C). This warmth helps the tubers to emerge more effectively.
  • Post-Emergence Phase: Once the tubers have emerged, reduce the temperature to around 58°F to 60°F (14°C to 16°C). This adjustment helps sustain healthy growth without promoting excessive elongation of the stems.

Humidity Control

Maintaining the right humidity levels in the greenhouse is equally important:

  • Initial Humidity: Aim for humidity levels around 80% during the early stages of growth. This can be achieved by ensuring good air circulation and a cracked vent.
  • Consistent Venting: During the day, keep venting consistent to maintain humidity levels around 60% to 65%. This balance helps prevent fungal diseases and promotes robust plant health.

Storage of Arum and Calla Lily Bulbs

Proper storage of lily bulbs during their dormant period is essential to preserve their viability and prepare them for the next planting season.

Preparation for Storage

  • Cleaning Bulbs: After digging up the bulbs, gently clean off any soil. Avoid washing the bulbs with water as this can increase the risk of rot.
  • Drying Bulbs: Allow the bulbs to air dry in a shaded, well-ventilated area for a few days. This drying process helps to harden the outer skin, making them less susceptible to rot during storage.

Storage Conditions

  • Temperature: Store the bulbs in a cool, dry place where temperatures are maintained between 41°F to 50°F (5°C to 10°C). Avoid exposing the bulbs to freezing temperatures, which can damage them.
  • Humidity: Keep the storage area relatively dry to prevent mold growth. High humidity levels can encourage fungal diseases.

Storage Containers

  • Material: Use breathable materials such as cardboard boxes, paper bags, or mesh bags for storage. These materials allow air circulation around the bulbs, reducing the risk of moisture buildup.
  • Medium: Pack the bulbs in peat moss, vermiculite, or sawdust. These materials help to absorb excess moisture and keep the bulbs dry.

Tips for Successful Overwintering

Monitoring and Maintenance

  • Regular Checks: Periodically check the bulbs during storage for any signs of rot or mold. Remove any affected bulbs immediately to prevent the spread of disease.
  • Ventilation: Ensure that the storage containers are kept in a well-ventilated area to maintain a dry environment.

Preparing for Replanting

  • Inspection: Before replanting in the spring, inspect the bulbs thoroughly. Discard any that appear soft, moldy, or damaged.
  • Soil Preparation: Prepare the planting site with well-draining soil enriched with organic matter. This creates an optimal environment for the bulbs to thrive once replanted.

Growing and Caring for Arum and Calla Lilies

Soil Preparation and Planting

  • Soil Type: These lilies thrive in well-draining soil enriched with organic matter. A pH range of 6.0 to 6.5 is ideal.
  • Planting Depth and Spacing: Plant bulbs about 5-10 cm deep and space them 30-40 cm apart to allow for adequate air circulation and growth.

Watering and Fertilization

  • Consistent Moisture: Keep the soil consistently moist but avoid waterlogging. Using drip irrigation or soaker hoses can help maintain the right moisture levels.
  • Balanced Fertilizer: Apply a balanced, slow-release fertilizer every few weeks during the growing season. Switch to a high-potassium fertilizer during the flowering phase to support bloom longevity.

Pest and Disease Management

  • Pests: Watch for aphids, thrips, and spider mites. Use insecticidal soap or neem oil to control infestations.
  • Diseases: Prevent fungal diseases by ensuring good air circulation and avoiding overhead watering.


Managing the temperature and storage conditions for Arum and Calla lily bulbs is crucial for their successful cultivation and longevity. By following the detailed guidelines provided, gardeners can ensure their lilies remain healthy during the dormant period and are ready to bloom beautifully in the next growing season. Proper temperature control in the greenhouse and careful storage practices will result in robust, vibrant lilies year after year.

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