Cassia vs Purple Fountain Grass Plant Comparison
Compare these two plants side by side — care needs, key differences, and which is right for your home.
Cassia
Senna spp. (formerly Cassia spp.)
Senna encompasses a diverse genus of flowering plants, ranging from small shrubs to medium-sized trees. Many species are known for their vibrant yellow flowers, often produced in large clusters, creating a visually striking display. The leaves are typically pinnately compound. While some species are cultivated for ornamental purposes, others have traditional medicinal uses. Senna plants are generally outdoor plants, thriving in warm climates with plenty of sunlight. Indoor cultivation is challenging due to their size and high light requirements.
Purple Fountain Grass
Pennisetum setaceum 'Rubrum'
Purple Fountain Grass is a striking ornamental grass prized for its arching, burgundy-purple foliage and bottlebrush-like flower plumes. It typically grows in a mounded form, reaching several feet in height and width. While technically a perennial in warmer climates, it is often grown as an annual in cooler regions due to its sensitivity to frost. It is primarily an outdoor plant, grown for its dramatic texture and color in gardens and landscapes. People grow it for its ornamental value, adding movement and visual interest to borders, containers, and mass plantings.
Quick Plant Comparison
| Feature | Cassia | Purple Fountain Grass |
|---|---|---|
| Light | Full sun (at least 6-8 hours of direct sunlight daily) | Full sun (at least 6 hours of direct sunlight per day) |
| Watering | Varies depending on climate and pot size, but typically every 1-2 weeks during the growing season. | Every 7-10 days, depending on weather and soil drainage |
| Humidity | 40-60% | 20-50% |
| Temperature | 18-30°C | 18-30°C |
| Care Level | Expert | Expert |
| Growth Rate | Moderate To Fast | Moderate |
| Max Height | Outdoor: Varies greatly by species, from 1-15 meters. Indoor: Highly unlikely to reach full size, but can reach 1-2 meters with difficulty. | Outdoor: 0.6-1.5 meters. Indoor (unlikely to thrive): 0.3-0.6 meters |
| Pet Safety | ❌ Toxic To Pets | ✅ Safe |
| Soil | Well-draining soil mix, such as a combination of potting soil, perlite, and sand. | Well-draining soil, such as a sandy loam or a potting mix amended with perlite |
| Beginner Friendly | ❌ No | ❌ No |
| Weekly Maintenance | 30 minutes weekly (including watering, fertilizing, and pruning) | 15 minutes weekly |
🔬 Botanical Information — Comparing These Plants
Cassia
| Scientific Name | Senna spp. (formerly Cassia spp.) |
|---|---|
| Family | Fabaceae |
| Native To | Various species originate from tropical and subtropical regions worldwide, including the Americas, Africa, and Asia. |
| Also Known As | Senna, Cassia, Golden Shower Tree, Popcorn Cassia, Candle Bush |
| Leaves | Typically pinnately compound leaves, with multiple leaflets arranged along a central stem. Leaflet shape and size vary by species. The leaves are often a vibrant green color. |
| Flowers | Senna plants produce showy, often bright yellow flowers in clusters. Flowering typically occurs during the warmer months. Indoor flowering is rare. |
Purple Fountain Grass
| Scientific Name | Pennisetum setaceum 'Rubrum' |
|---|---|
| Family | Poaceae |
| Native To | Hybrid cultivar; species native to Africa, Southwest Asia |
| Also Known As | Purple Fountain Grass, Red Fountain Grass |
| Leaves | The leaves are long, narrow, and arching, with a deep burgundy-purple color. They have a fine texture and create a graceful, flowing appearance. |
| Flowers | It produces bottlebrush-like flower plumes that are initially a deep burgundy-purple, fading to a tan color as they mature. Flowering typically occurs in summer and fall. It is unlikely to flower indoors. |
📏 Size & Growth — Plant Comparison
Cassia
Purple Fountain Grass
🌱 Propagation — Comparing Plant Growth
Cassia
Methods: Seed, stem cuttings
Difficulty: Moderate
Tips: For seeds, scarify the seed coat and soak in warm water for 24 hours before planting. Stem cuttings should be taken from semi-hardwood growth and rooted in a well-draining medium.
Purple Fountain Grass
Methods: Seed, Division
Difficulty: Moderate
Tips: Divide clumps in spring or early summer. Sow seeds indoors 6-8 weeks before the last frost.
✨ Benefits & Features — Comparing Plant Value
Cassia
Senna plants are known for their vibrant yellow flowers and their traditional medicinal uses. Many species were formerly classified under the genus Cassia, leading to some confusion in nomenclature.
- ✓ Provides vibrant color to the garden.
- ✓ Attracts pollinators like bees and butterflies.
- ✓ Can be used for traditional medicinal purposes (with caution).
- ✓ Offers shade in warm climates.
- ✓ Provides a sense of accomplishment for experienced gardeners.
- ⚠️ Toxic to pets
Purple Fountain Grass
Its deep purple foliage and graceful, arching habit make it a standout in any garden. The bottlebrush-like flower plumes add further visual interest and movement.
- ✓ Adds visual interest and texture to the garden
- ✓ Attracts birds
- ✓ Drought tolerant
- ✓ Deer resistant
- ✓ Provides movement in the landscape
- 🐾 Pet Safe
📅 Maintenance Schedule — Plant Care Comparison
Cassia
Purple Fountain Grass
🌞 Light Requirements
Cassia
Full sun (at least 6-8 hours of direct sunlight daily)
Low light tolerant: ❌ No
Purple Fountain Grass
Full sun (at least 6 hours of direct sunlight per day)
Low light tolerant: ❌ No
💧 Watering Needs
Cassia
Water thoroughly when the top inch of soil is dry. Allow the soil to dry out slightly between waterings. Overwatering can lead to root rot, while underwatering can cause leaf drop and stunted growth. Ensure good drainage.
Purple Fountain Grass
Water deeply when the top inch of soil feels dry to the touch. Avoid overwatering, which can lead to root rot. Signs of underwatering include drooping or browning leaves. Signs of overwatering include yellowing leaves and soggy soil.
🌡️ Temperature & Humidity
Cassia
Temperature: 18-30°C
Humidity: 40-60%
Purple Fountain Grass
Temperature: 18-30°C
Humidity: 20-50%
🤔 Which Plant Is Right For You?
Cassia
Senna spp. (formerly Cassia spp.)Experienced gardeners in warm climates who want a vibrant flowering shrub or small tree for their outdoor space.
✅ Choose This Plant If...
- You live in a warm climate with plenty of sunshine and want a vibrant flowering plant for your garden.
- You are an experienced gardener looking for a challenging and rewarding plant to grow.
- You are interested in the traditional medicinal uses of Senna (under the guidance of a qualified herbalist).
- You have a large outdoor space that can accommodate the plant's mature size.
- You are prepared to provide the plant with the specific care it needs, including full sun and well-draining soil.
❌ Skip This Plant If...
- You live in a cold climate with limited sunlight.
- You have pets or small children who may be at risk of poisoning.
- You are a beginner gardener looking for an easy-to-care-for plant.
- You have limited space and cannot accommodate the plant's mature size.
- You are not prepared to provide the plant with the specific care it needs.
Purple Fountain Grass
Pennisetum setaceum 'Rubrum'Gardeners looking for a dramatic ornamental grass to add color and texture to their landscape.
✅ Choose This Plant If...
- You want a striking focal point in your garden.
- You need a drought-tolerant plant for a sunny location.
- You desire a plant with beautiful purple foliage and plumes.
- You want to attract birds to your garden.
- You need a deer-resistant plant.
❌ Skip This Plant If...
- You live in a cold climate and don't want to treat it as an annual.
- You don't have a sunny location.
- You are looking for a low-maintenance indoor plant.
🎯 Quick Verdict
⚡ Key Differences Between These Plants
Cassia needs full sun (at least 6-8 hours of direct sunlight daily), while Purple Fountain Grass prefers full sun (at least 6 hours of direct sunlight per day).
Cassia has moderate to fast growth, while Purple Fountain Grass grows moderate.
💡 Pro Tips For Comparing These Plants
Cassia Care Tips
Senna plants are primarily outdoor plants that require full sun and well-draining soil. Indoor cultivation is extremely challenging due to their high light requirements and potential size. They are also toxic to pets, making them unsuitable for households with animals. Requires careful monitoring of watering and fertilization.
- Provide full sun for optimal flowering.
- Ensure well-draining soil to prevent root rot.
- Water deeply but infrequently, allowing the soil to dry out slightly between waterings.
- Fertilize regularly during the growing season.
- Prune after flowering to maintain shape and encourage new growth.
Purple Fountain Grass Care Tips
Purple Fountain Grass is primarily an outdoor plant and will struggle indoors due to its high light requirements. It needs full sun and well-draining soil. While it can be grown in containers, it requires regular watering and fertilization. Overwintering indoors is possible in colder climates, but the plant may not thrive.
- Plant in well-draining soil in a sunny location.
- Water deeply but infrequently, allowing the soil to dry out between waterings.
- Fertilize in spring with a balanced slow-release fertilizer.
- Cut back foliage in late fall or early spring.
- Protect from frost in colder climates.
⚠️ Common Problems & Solutions — Plant Care Comparison
Cassia
Purple Fountain Grass
❓ Frequently Asked Questions — Comparing These Plants
Cassia
What are the light requirements for Cassia?
Cassia thrives in bright, indirect light. A south-facing or west-facing window with filtered light is ideal. Insufficient light can result in leggy growth and reduced flowering. If natural light is limited, supplement with grow lights, positioning them 6-12 inches above the plant. Rotate the plant regularly to ensure even light exposure on all sides. Avoid direct sunlight, especially during the hottest part of the day, as it can scorch the leaves. Signs of inadequate light include pale leaves, elongated stems, and a lack of blooms. Adjust the plant’s location or supplement with artificial light accordingly.
How do I care for Cassia?
Caring for Cassia as an indoor tree involves providing it with ample bright, indirect light; direct sunlight can scorch the leaves. Water thoroughly when the top inch of soil feels dry, ensuring proper drainage to prevent root rot. Maintain a moderate humidity level, especially during winter when indoor air tends to be drier. Fertilize monthly during the growing season (spring and summer) with a balanced liquid fertilizer. Prune regularly to maintain its shape and encourage bushier growth. Repot every 2-3 years, or when the plant becomes root-bound, using a well-draining potting mix. Monitor for pests and diseases, addressing any issues promptly. Avoid sudden changes in temperature or environment, as Cassia prefers stable conditions. Provide support if the branches become too heavy with blooms.
How do I propagate Cassia?
Cassia can be propagated through stem cuttings or air layering. For stem cuttings, take a 4-6 inch cutting from a healthy stem. Remove the lower leaves and dip the cut end in rooting hormone. Plant the cutting in a well-draining potting mix and keep it moist. For air layering, make a small cut in a stem and wrap it with moist sphagnum moss. Cover the moss with plastic wrap and secure it with tape. Once roots develop, cut the stem below the roots and plant it in a pot. Both methods require warm temperatures and high humidity. Success rates are higher in spring or early summer. Be patient, as rooting can take several weeks.
Purple Fountain Grass
What are the light requirements for Purple Fountain Grass?
Purple Fountain Grass requires at least 6-8 hours of direct sunlight per day to thrive and develop its characteristic vibrant purple foliage and abundant flower plumes. Insufficient sunlight can lead to leggy growth, faded color, and reduced flowering. When planting, choose a location that receives full sun throughout the day. If growing in containers, rotate the plant regularly to ensure even sun exposure on all sides. In hotter climates, some afternoon shade may be beneficial to prevent scorching, but avoid placing it in deep shade, which will hinder its growth. Supplemental lighting may be necessary if grown indoors during winter months.
How do I care for Purple Fountain Grass?
Purple Fountain Grass thrives in full sun and well-draining soil. Water thoroughly when the top inch of soil feels dry, but avoid overwatering, which can lead to root rot. Fertilize monthly during the growing season (spring and summer) with a balanced fertilizer to promote healthy growth and vibrant blooms. Prune away dead or damaged foliage in late winter or early spring before new growth emerges. In colder climates, treat it as an annual or bring it indoors during the winter. Provide adequate air circulation to prevent fungal diseases. Regularly inspect for pests like aphids or spider mites, and treat accordingly. Avoid planting in overly compacted or poorly draining soil. Mulching around the base can help retain moisture and suppress weeds. Protect from strong winds.
How do I propagate Purple Fountain Grass?
Purple Fountain Grass can be propagated by division. In early spring, carefully dig up the plant and divide the root ball into smaller clumps, ensuring each clump has healthy roots and foliage. Replant the divisions in well-draining soil and water thoroughly. Keep the soil consistently moist until the new plants are established. Division is the most reliable method. Seed propagation is possible but can be inconsistent in producing plants true to the ‘Rubrum’ cultivar. Stem cuttings are not typically used for propagating this grass. Keikis are not applicable as this plant doesn’t produce them. Ensure good air circulation to prevent fungal diseases after dividing.
Last updated: April 25, 2026 — Plant care data reviewed and verified by our editorial team.