Arum lilies and Calla lilies are not the same plant, even among gardeners who know the difference. Although the two are related and bear a strong resemblance, they differ in some important ways. Understanding these differences can help in determining which is best for your garden. By learning about their specific needs and traits, you can choose the right lily for your climate and garden, ensuring a beautiful and healthy display.
Arum lilies (Zantedeschia aethiopica) and Calla lilies (Zantedeschia elliottiana and Zantedeschia rehmannii) belong to the family Araceae. Arum lilies are native to southern Africa, specifically Lesotho, South Africa, and Eswatini. They are known for their large, white spathes and central yellow spadix. Calla lilies, on the other hand, are also native to southern Africa. There are species that are known for their bright colors, from yellow to pink and purple, and hybrids of these species are often found in gardens. These species have been introduced worldwide and are popular in ornamental gardening.
With their sculptural blooms and lush foliage, both arum lilies and calla lilies make striking statements in the garden. But despite their visual similarities, these plants have key differences.
Understanding these distinctions will help you determine which lily best suits your landscape needs and growing conditions This guide covers everything you need to know about choosing, cultivating and enjoying these beautiful botanicals.
Appearance and Growth Habit
Arum lilies are clump-forming perennials with broad, arrowhead-shaped leaves. Flower stalks emerge in summer, topped with a showy white spathe surrounding a spiky central spadix.
- Reach 2-4 feet tall and 2 feet wide.
- Hardy in USDA zones 7-10.
- Grow in part to full shade.
- Spread rapidly in ideal conditions.
Calla lilies have heart-shaped leaves and smaller blooms on shorter stems. The spathe comes in many colors beyond white
- Grow 1-3 feet tall and 1-2 feet wide.
- Tend to be annual/tender perennials in zones 8-11.
- Require full sun to part shade.
- Spread slowly.
Flower Structure
The flowers of both plants feature:
- A modified leaf called a spathe. It wraps around or overlays the bloom.
- A spadix, the spike of small, tightly packed actual flowers.
For arum lilies, the spadix protrudes prominently above the surrounding spathe. Calla lily spadices are fully enclosed in the spathe.
Available Colors
Arum lily spathes come primarily in white, with some green or pink tinged varieties.
Calla lily spathes span a rainbow of hot to pastel tones:
- Red, orange, yellow, pink, purple, black
- Bi-colors like purple picotee
- White, green
Ideal Growing Conditions
Arum lilies thrive in:
- Part to full shade
- Consistently moist, rich soil
- Hot humid climates (Zones 7-10)
Calla lilies grow best in:
- Full sun to part shade
- Well-drained soil
- Warm zones 8-11
- Can be grown as annuals/potted plants in cooler climates
Arum lilies tolerate soggy soil, even standing water. Callas need soil to dry out between waterings.
Maintenance and Care
For arum lilies:
- Provide supplemental water in dry periods
- Divide crowded clumps every 2-3 years
- Cut off spent flower stems
- May require reduced irrigation in winter
For calla lilies:
- Water when top inch of soil is dry
- Fertilize monthly in spring/summer
- Cut back stems and leaves after flowering
- Dig up bulbs in fall if not winter hardy
Growth Rate and Spread
Left undisturbed, arum lilies spread aggressively by both bulb offsets and seed. They can quickly overwhelm a space.
Calla lilies multiply slowly, mainly by small new bulbs called cormels that form around the parent. Manageable expansion rate.
Invasiveness and Environmental Impact
In ideal growing conditions, arum lilies readily spread into natural areas and become invasive. For this reason they are prohibited or controlled in parts of Australia and New Zealand.
Calla lilies are non-invasive and eco-friendly, making them a sound choice for gardeners concerned about habitat preservation.
Uses in the Landscape
Arum lilies make excellent:
- Backdrops along fences or property lines
- Living screens for privacy
- Naturalistic masses near water features
Calla lilies shine as:
- Poolside plantings
- Container plants on patios, decks
- Borders along paths and walkways
- Cut flowers
Design Styles Suited To Each Lily
Arum lilies fit seamlessly into:
- Woodland gardens
- Asian-inspired designs
- Tropical gardens
- Wetland landscapes
Calla lilies enhance:
- Cottage gardens
- Mediterranean gardens
- Modern floral designs
- Container plantings
Takeaways
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Arum lilies are hardy, shade lovers that spread vigorously. Calla lilies require sun and expand slowly.
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Arum lily spathes come in white, green, pink. Calla lily spathes offer a rainbow of vibrant hues.
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Calla lilies are the eco-friendly choice. Arum lilies can become invasive.
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Choose arum lilies for woodland areas, callas for border plantings and containers.
Now that you know the key similarities and differences, decide which lily fits your site and style! Both deliver distinctive beauty uncommon in the garden.
Growing Conditions and Care
Arum lilies do best in shady, damp places, so they do well when planted near ponds, marshes, and other places that stay wet all the time. They prefer rich, well-draining soil and can tolerate heavy clay soils as long as they are kept moist. These lilies are hardy and can withstand temperatures as low as -23°C, making them suitable for cooler climates. In places where they might spread quickly, it is important to control their growth by getting rid of their seed heads and stopping their rhizomes from spreading.
Calla lilies prefer sunny locations with well-draining soil. They do not do well in very wet conditions like Arum lilies do. Instead, they do better in garden beds and containers where the soil moisture can be controlled. They are less cold-hardy, typically surviving in temperatures down to -12°C. In cooler climates, Calla lilies are often grown as tender bulbs or houseplants to protect them from frost. They benefit from a balanced fertilizer during the growing season to support their vibrant blooms.
Arum lilies are more cold-tolerant and can thrive in wetter, shadier environments compared to Calla lilies. Their ability to grow in marshy conditions makes them versatile but also potentially invasive in suitable habitats. On the other hand, calla lilies need more sunlight and soil that doesn’t stay soggy. This makes them less able to handle wet conditions but perfect for garden beds and pots. Their wide range of bright colors and small size make them more useful for ornamental gardening, especially in places where they won’t be exposed to harsh winters.
Arum Lilies (Zantedeschia aethiopica): Arum lilies propagate through both seeds and vegetative means. The seeds are dispersed by birds and water, which can lead to rapid spread in suitable environments. Vegetative propagation occurs via rhizomes, which are underground stems that produce new shoots. Rhizomes can be divided and transplanted, making this a common method for gardeners. Because they can spread quickly through rhizome offsets, they can quickly form dense colonies if they are not managed properly.
Calla Lilies (Zantedeschia elliottiana and Zantedeschia rehmannii): Calla lilies primarily propagate through tubers, which are swollen underground stems. Tubers can be divided and replanted, and this method is commonly used to propagate new plants. Some species can also propagate through seeds, but this is less common in horticultural practice. The tubers are typically planted in the spring, and they require a period of dormancy during the winter.
Arum lilies have a significant potential for invasiveness, particularly in wet and marshy areas. Their ability to propagate through both seeds and rhizomes allows them to spread quickly. In regions like Western Australia, they have become problematic weeds, outcompeting native vegetation and disrupting local ecosystems. Arum lilies grow in dense colonies that can block waterways, change the flow of water, and hurt the variety of plants and animals that live in wetland areas. To keep them from spreading too far, you should get rid of their seed heads after they flower and stop the rhizomes from spreading.
Calla lilies, on the other hand, are less likely to spread because they grow more slowly and like well-drained soil. They do not thrive in the same wet conditions that facilitate the rapid spread of Arum lilies. Additionally, their propagation through tubers means they do not spread as aggressively. Calla lilies are generally not seen as a threat to native ecosystems because of this. They can be planted in a wide range of garden settings without worrying about them spreading.
Flowering and Visual Appeal
Both Arum and Calla lilies produce inflorescences that consist of a spathe and spadix. The spathe is a large, colorful bract that surrounds the spadix, a central spike covered with tiny flowers. The spathe of an Arum lily is usually pure white and can grow up to 25 cm long. It stands out against the yellow spadix in a striking way. Depending on the species and cultivar, calla lilies have a wider range of spathe colors, such as yellow, pink, purple, and even dark maroon.
Arum Lilies:
- The spathes are mostly white, but some types have hints of pink or green.
- The spadix is usually yellow.
- The leaves are big, wide, and dark green, and they make a lush background for the flowers.
Calla Lilies:
- Wide range of spathe colors, including yellow (Z. elliottiana), pink, and purple (Z. rehmannii).
- Spadices are typically yellow but can vary.
- Leaves often have white spots on them, which makes them look even more interesting.
- Calla lilies are small and come in many colors, which makes them useful for decorating gardens and flower arrangements.
Arum Lilies:
- Bloom from late winter to late spring.
- They can make inflorescences more than once a year in places with enough moisture and mild temperatures.
Calla Lilies:
- Primarily bloom in the summer.
- Flowering can last into late summer if the plants are grown in the best conditions, with enough sunlight and soil that doesn’t stay soggy.
Knowing when these flowers bloom can help gardeners plan their layouts so that both Arum and Calla lilies bloom continuously throughout the growing season, making the most of their unique looks.
Calla Lily Care Guide – Picking, Placing, and Parenting Your Plant
FAQ
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