Calla vs Cosmos Plant Comparison
Compare these two plants side by side — care needs, key differences, and which is right for your home.
Calla
Zantedeschia aethiopica
Zantedeschia aethiopica, commonly known as Calla Lily, is a rhizomatous herbaceous perennial prized for its elegant, trumpet-shaped spathes (modified leaves) that surround a central spadix. While often called a lily, it is not a true lily. It grows from rhizomes, producing large, arrow-shaped, glossy green leaves. It is primarily an outdoor plant, thriving in moist conditions. People grow it for its striking flowers, often used in bouquets and floral arrangements. It can be grown indoors, but requires specific conditions to thrive and may not flower as readily as outdoors.
Cosmos
Cosmos bipinnatus
Cosmos bipinnatus is an annual flowering plant typically grown outdoors. It features delicate, fern-like foliage and daisy-like flowers in shades of pink, purple, white, and occasionally yellow or orange. Plants typically reach heights of 1 to 6 feet. Cosmos are popular for their long blooming season, attracting pollinators like bees and butterflies. They are primarily grown for ornamental purposes in gardens and meadows, adding color and texture to landscapes. While relatively easy to grow outdoors, they are not well-suited for indoor cultivation due to their high light requirements and large size.
Quick Plant Comparison
| Feature | Calla | Cosmos |
|---|---|---|
| Light | Bright, indirect light to full sun outdoors. Indoors, provide bright indirect light, ideally near an east- or west-facing window. | Full sun (at least 6-8 hours of direct sunlight daily) |
| Watering | Every 3-7 days during the growing season, less frequently in winter. | Every 1-2 weeks, depending on weather and soil drainage |
| Humidity | 40-60% | 30-50% |
| Temperature | 18-24°C | 18-27°C |
| Care Level | Moderate | Expert |
| Growth Rate | Moderate | Fast |
| Max Height | Indoors: 0.6-1 meter | N/A (Outdoor plant, unsuitable for indoor growing) |
| Pet Safety | ❌ Toxic To Pets | ✅ Safe |
| Soil | Well-draining potting mix rich in organic matter. A mix of peat moss, perlite, and compost is suitable. | Well-draining soil; sandy or loamy soil is ideal |
| Beginner Friendly | With Caution | ✅ Yes |
| Weekly Maintenance | 10 minutes weekly | 5 minutes weekly |
🔬 Botanical Information — Comparing These Plants
Calla
| Scientific Name | Zantedeschia aethiopica |
|---|---|
| Family | Araceae |
| Native To | South Africa |
| Also Known As | Calla Lily, Arum Lily, Trumpet Lily |
| Leaves | Large, arrow-shaped, glossy green leaves. The leaves can be up to 45 cm long and 25 cm wide. Some varieties have speckled or variegated leaves. |
| Flowers | Can flower indoors with proper care, but more reliably flowers outdoors. The 'flower' is a modified leaf called a spathe, which is typically white, but can also be pink, yellow, orange, or purple. The spadix, the yellow spike in the center, is where the true flowers are located. |
Cosmos
| Scientific Name | Cosmos bipinnatus |
|---|---|
| Family | Asteraceae |
| Native To | Mexico |
| Also Known As | Cosmos, Garden Cosmos, Mexican Aster |
| Leaves | The leaves of Cosmos bipinnatus are finely divided and fern-like, giving the plant a delicate and airy appearance. They are typically green in color and arranged oppositely along the stems. The leaves are relatively small, adding to the plant's overall graceful form. |
| Flowers | Cosmos rarely, if ever, flower indoors due to insufficient light. Outdoors, they produce daisy-like flowers with a central disc and ray florets in shades of pink, purple, white, and occasionally yellow or orange. The flowers are typically 2-4 inches in diameter and bloom profusely throughout the summer and fall. |
📏 Size & Growth — Plant Comparison
Calla
Cosmos
🌱 Propagation — Comparing Plant Growth
Calla
Methods: Division, Seed
Difficulty: Moderate
Tips: Divide rhizomes in early spring before new growth begins. Ensure each division has at least one eye (bud). Plant divisions in well-draining soil and keep moist. Seed propagation is possible but slower.
Cosmos
Methods: Seed
Difficulty: Easy
Tips: Sow seeds directly into the garden after the last frost or start indoors 4-6 weeks before the last frost. Lightly cover seeds with soil and keep moist until germination.
✨ Benefits & Features — Comparing Plant Value
Calla
The Calla Lily is not a true lily, but a rhizomatous perennial with a unique spathe and spadix flower structure. Its elegant, trumpet-shaped flowers make it a popular choice for bouquets and floral arrangements. It requires a dormant period in winter to promote flowering in the following season.
- ✓ Aesthetically pleasing flowers.
- ✓ Can be used for cut flower arrangements.
- ✓ Adds a touch of elegance to any room.
- ✓ Can improve mood and reduce stress.
- ✓ Provides a sense of accomplishment through successful care.
- ⚠️ Toxic to pets
Cosmos
Cosmos are known for their delicate, fern-like foliage and daisy-like flowers that come in a variety of colors. They are also highly attractive to pollinators, making them a valuable addition to any garden. Their long blooming season provides continuous color throughout the summer and fall.
- ✓ Attracts pollinators to your garden.
- ✓ Provides beautiful cut flowers.
- ✓ Adds vibrant color to your outdoor space.
- ✓ Easy to grow and maintain.
- ✓ Supports local ecosystems.
- 🐾 Pet Safe
📅 Maintenance Schedule — Plant Care Comparison
Calla
Cosmos
🌞 Light Requirements
Calla
Bright, indirect light to full sun outdoors. Indoors, provide bright indirect light, ideally near an east- or west-facing window.
Low light tolerant: ❌ No
Cosmos
Full sun (at least 6-8 hours of direct sunlight daily)
Low light tolerant: ❌ No
💧 Watering Needs
Calla
Keep the soil consistently moist, especially during the growing season. Water thoroughly when the top inch of soil feels dry. Reduce watering in the dormant period. Overwatering can lead to rhizome rot, indicated by yellowing leaves and a foul odor. Underwatering results in wilting and browning leaf tips.
Cosmos
Water deeply when the top inch of soil feels dry. Avoid overwatering, which can lead to root rot. Cosmos are relatively drought-tolerant once established. Signs of underwatering include wilting and drooping leaves. Overwatering can cause yellowing leaves and stem rot.
🌡️ Temperature & Humidity
Calla
Temperature: 18-24°C
Humidity: 40-60%
Cosmos
Temperature: 18-27°C
Humidity: 30-50%
🤔 Which Plant Is Right For You?
Calla
Zantedeschia aethiopicaExperienced plant enthusiasts seeking a flowering plant with elegant blooms, willing to provide specific care requirements.
✅ Choose This Plant If...
- You appreciate elegant, trumpet-shaped flowers.
- You can provide bright, indirect light and consistent moisture.
- You are willing to provide a dormant period in winter.
- You are experienced with plant care and can address potential problems.
- You want a plant that can be used for cut flower arrangements.
❌ Skip This Plant If...
- You have pets that may ingest the plant.
- You cannot provide bright light or consistent moisture.
- You are a beginner plant owner.
- You prefer low-maintenance plants.
Cosmos
Cosmos bipinnatusGardeners looking for easy-to-grow, colorful annuals that attract pollinators.
✅ Choose This Plant If...
- You want a low-maintenance plant for your garden.
- You want to attract butterflies and bees to your yard.
- You need a plant that blooms for a long period.
- You want to add vibrant colors to your outdoor space.
- You want easy-to-grow cut flowers.
❌ Skip This Plant If...
- You don't have a sunny outdoor space.
- You want a plant that thrives indoors.
- You live in a very cold climate with a short growing season.
🎯 Quick Verdict
⚡ Key Differences Between These Plants
Calla is rated Moderate care level, while Cosmos is Expert.
Calla has moderate growth, while Cosmos grows fast.
💡 Pro Tips For Comparing These Plants
Calla Care Tips
Calla Lilies require bright light and consistent moisture. They can be grown indoors, but may not flower as readily as outdoors. Ensure good drainage to prevent rhizome rot. Toxicity to pets is a significant concern. Requires a dormant period in winter.
- Provide a dormant period in winter by reducing watering and keeping the plant in a cool location.
- Ensure good drainage to prevent rhizome rot.
- Fertilize regularly during the growing season to promote flowering.
- Monitor for pests and diseases and treat promptly.
- Provide bright, indirect light for optimal growth and flowering.
Cosmos Care Tips
Cosmos are easy to grow outdoors in full sun and well-draining soil. They are not suitable for indoor growing due to their high light requirements and large size. Attempting to grow them indoors will likely result in leggy, weak plants with few flowers.
- Deadhead spent flowers regularly to encourage more blooms.
- Provide support for taller varieties to prevent them from flopping over.
- Water deeply but infrequently, allowing the soil to dry out slightly between waterings.
- Avoid over-fertilizing, as this can lead to excessive foliage growth and fewer flowers.
- Plant in well-draining soil to prevent root rot.
⚠️ Common Problems & Solutions — Plant Care Comparison
Calla
Cosmos
❓ Frequently Asked Questions — Comparing These Plants
Calla
What are the light requirements for Calla?
Calla lilies thrive in bright, indirect light. Direct sunlight can scorch their leaves, so avoid placing them in south-facing windows without some form of shading. An east- or west-facing window is ideal, providing ample light without the intensity of direct sun. If you notice the leaves becoming pale or the plant failing to bloom, it may not be receiving enough light. In such cases, consider supplementing with artificial grow lights. During the darker winter months, supplemental lighting is particularly beneficial to maintain healthy growth and encourage future blooms. Ensure the light is diffused to prevent leaf burn. Regular rotation of the plant ensures all sides receive adequate light, preventing uneven growth.
How do I care for Calla?
Calla lilies require bright, indirect light for optimal growth and blooming. Water thoroughly when the top inch of soil feels dry, ensuring proper drainage to prevent root rot. During the growing season (spring and summer), fertilize every 2-4 weeks with a balanced liquid fertilizer diluted to half strength to encourage flowering. Reduce watering and fertilization during the dormant period in fall and winter. Maintain a humidity level of 50-60%. Repot annually in spring using well-draining potting mix. Remove spent flowers to encourage more blooms. Monitor for pests like aphids and spider mites, and treat promptly if detected. Provide support for taller varieties to prevent them from bending. Rotate the plant regularly to ensure even growth and prevent leaning towards the light source. Protect from frost and freezing temperatures.
How do I propagate Calla?
Calla lilies can be propagated by division, stem cuttings (though less common), and keiki (small plantlets that sometimes form on the plant).
Cosmos
What are the light requirements for Cosmos?
Cosmos require a minimum of six to eight hours of direct sunlight per day to thrive and produce abundant blooms. Insufficient sunlight can result in leggy growth, weak stems, and reduced flowering. Choose a sunny location in your garden or on your balcony where the plants will receive ample sunlight throughout the day. If growing Cosmos indoors, place them near a south-facing window that provides the brightest light. Rotate the plants regularly to ensure even exposure to sunlight on all sides. If natural light is insufficient, supplement with grow lights to provide the necessary light intensity.
How do I care for Cosmos?
Cosmos thrive in full sun and well-draining soil. Water regularly, especially during dry periods, but avoid overwatering to prevent root rot. Fertilize lightly every few weeks with a balanced fertilizer, or a bloom-boosting formula during the flowering season, to encourage abundant blooms. Deadhead spent flowers regularly to promote continuous blooming. Cosmos are generally low-maintenance plants, but they may benefit from staking if they become tall and leggy. Prune them lightly to maintain their shape and encourage bushier growth. Protect them from strong winds, which can damage the delicate stems. Monitor for pests like aphids and treat them promptly if detected. Cosmos are generally annuals, but they may self-seed in some climates.
How do I propagate Cosmos?
Cosmos are most commonly propagated by seed. Sow seeds directly into the garden in spring after the last frost, or start them indoors 6-8 weeks earlier. For division, carefully dig up the plant in early spring or fall and separate the root ball into smaller clumps, ensuring each clump has healthy roots and foliage. Replant the divisions immediately in well-draining soil. Stem cuttings are not a common method for Cosmos, but can be attempted by taking 4-6 inch cuttings from new growth in spring, dipping them in rooting hormone, and planting them in moist potting mix. Keiki propagation is not applicable to Cosmos.
Last updated: May 1, 2026 — Plant care data reviewed and verified by our editorial team.