Calla Lilies: A Comprehensive Guide to Growing Them Outdoors

Introduction

Calla lilies, with their elegant trumpet-shaped flowers and glossy foliage, are a popular choice for ornamental gardens. While they are often associated with indoor cultivation, certain varieties of calla lilies can thrive outdoors in the right conditions. This in-depth guide will provide you with all the essential information you need to successfully grow calla lilies outdoors, from selecting suitable varieties to providing proper care.

Selecting Calla Lily Varieties for Outdoor Cultivation

Hardy Calla Lilies

For reliable outdoor growth, choose hardy calla lily varieties that can withstand cold temperatures. These varieties typically belong to the genus Zantedeschia aethiopica and include:

• Z. aethiopica ‘Green Goddess’
• Z. aethiopica ‘Crowborough’
• Z. aethiopica ‘White Giant’

Tender Calla Lilies

Tender calla lily varieties, such as those in the genus Calla, are not as cold-hardy and may require protection or overwintering indoors in colder climates. Some popular tender calla lilies include:

• Calla palustris
• Calla rehmannii
• Calla Elliottiana

Preparing the Soil and Planting Calla Lilies Outdoors

Soil Requirements

Calla lilies prefer rich, well-drained soil with a pH between 5.5 and 6.5. Amend the soil with organic matter, such as compost or peat moss, to improve drainage and fertility.

Planting Time

Plant calla lilies outdoors in the spring after the last frost date. If you live in a cold climate, you may want to start them indoors 6-8 weeks before the last frost.

Planting Depth and Spacing

Plant calla lily bulbs 2-4 inches deep and 6-12 inches apart. Point the growing tip of the bulb upward.

Caring for Calla Lilies Outdoors

Watering

Calla lilies need moderate watering, especially during hot, dry weather. Water deeply and allow the soil to dry out slightly between waterings.

Fertilizing

Fertilize calla lilies monthly with a balanced fertilizer. Use a fertilizer that is high in phosphorus and potassium, such as a 5-10-5 formula.

Mulching

Mulch around calla lilies with organic matter, such as bark or shredded leaves, to retain moisture and suppress weeds.

Deadheading

Remove spent flowers to encourage continued blooming.

Overwintering Calla Lilies in Cold Climates

Hardy Calla Lilies

Hardy calla lilies can survive winter in USDA hardiness zones 6 and higher. In colder zones, mulch heavily or dig up the bulbs and store them in a cool, dry place over winter.

Tender Calla Lilies

Tender calla lilies must be dug up and overwintered indoors in cold climates. Dig up the bulbs in the fall and store them in a cool, dark place with temperatures between 40-50°F.

Common Problems and Solutions

Yellowing Leaves

Yellowing leaves can indicate overwatering or nutrient deficiency. Check the soil moisture and adjust watering accordingly. Fertilize calla lilies monthly with a balanced fertilizer.

Brown Spots on Leaves

Brown spots on leaves may be caused by fungal diseases, such as leaf spot or botrytis. Treat with a fungicide and remove infected leaves.

Aphids

Aphids are small, sap-sucking insects that can infest calla lilies. Control aphids with insecticidal soap or neem oil.

Conclusion

Growing calla lilies outdoors can be a rewarding experience, adding beauty and elegance to your garden. By selecting suitable varieties, preparing the soil properly, and providing appropriate care, you can enjoy the graceful blooms of calla lilies for seasons to come. Remember to pay attention to the specific needs of your chosen calla lily variety, whether hardy or tender, to ensure optimal growth and performance.