False Dragonhead vs Lemon Grass Plant Comparison
Compare these two plants side by side — care needs, key differences, and which is right for your home.
False Dragonhead
Physostegia virginiana
Physostegia virginiana, commonly known as False Dragonhead or Obedience Plant, is a rhizomatous perennial herb typically found in moist meadows and along stream banks. It features upright, square stems and lance-shaped, toothed leaves. The plant produces dense spikes of tubular, two-lipped flowers in shades of pink, purple, or white during late summer and early fall. While admired for its late-season blooms and ease of cultivation, its aggressive spreading habit via rhizomes can make it challenging to manage in smaller gardens. It is primarily grown outdoors in gardens and naturalized areas.
Lemon Grass
Cymbopogon citratus
Lemon Grass is a tall, perennial grass characterized by its fragrant, lemon-scented leaves and stalks. It typically grows in dense clumps, reaching heights of up to 1.8 meters (6 feet) outdoors. The plant is primarily cultivated for culinary and medicinal purposes, with its stalks and leaves used to flavor dishes, teas, and herbal remedies. While it can be grown indoors, it requires very bright light and may not thrive as well as it does outdoors. People grow it for its unique flavor and aroma, as well as its potential health benefits.
Quick Plant Comparison
| Feature | False Dragonhead | Lemon Grass |
|---|---|---|
| Light | Full sun to partial shade. Requires at least 6 hours of direct sunlight for optimal flowering. | Full sun (at least 6-8 hours of direct sunlight daily) |
| Watering | Every 7-10 days, depending on weather and soil drainage. | Every 2-3 days during the growing season, less frequently in winter (every 7-10 days) |
| Humidity | 30-50% | 40-60% |
| Temperature | 15-27°C | 18-30°C |
| Care Level | Expert | Expert |
| Growth Rate | Fast | Fast |
| Max Height | Grown indoors, rarely flowers and reaches 30-60 cm. Outdoors, 60-120 cm. | 0.6-1.2 meters (2-4 feet) indoors, up to 1.8 meters (6 feet) outdoors |
| Pet Safety | ❌ Toxic To Pets | ❌ Toxic To Pets |
| Soil | Well-drained soil, loamy or sandy soil is best. Tolerates a range of soil types. | Well-draining, loamy soil. A mix of potting soil, sand, and perlite is suitable. |
| Beginner Friendly | ❌ No | ❌ No |
| Weekly Maintenance | 30 minutes weekly during growing season (including watering, weeding, and pruning). | 15 minutes weekly |
🔬 Botanical Information — Comparing These Plants
False Dragonhead
| Scientific Name | Physostegia virginiana |
|---|---|
| Family | Lamiaceae |
| Native To | Eastern and Central North America |
| Also Known As | False Dragonhead, Obedience Plant |
| Leaves | Lance-shaped, toothed leaves that are arranged oppositely along the square stems. The leaves are typically green and can be up to 15 cm long. |
| Flowers | Rarely flowers indoors. Outdoors, it produces dense spikes of tubular, two-lipped flowers in shades of pink, purple, or white during late summer and early fall. |
Lemon Grass
| Scientific Name | Cymbopogon citratus |
|---|---|
| Family | Poaceae |
| Native To | Southeast Asia (India, Sri Lanka, Malaysia, Thailand) |
| Also Known As | Lemon Grass, Lemongrass, Oil Grass, Fever Grass, Tanglad |
| Leaves | The leaves of Lemon Grass are long, slender, and blade-like, typically reaching lengths of 30-90 cm (12-35 inches). They are a vibrant green color and have a slightly rough texture. The leaves have a prominent midrib and taper to a sharp point. When crushed, they release a strong lemon scent. |
| Flowers | Lemon Grass rarely flowers indoors. Outdoors, it may produce flower spikes in warm climates, but flowering is infrequent and not the primary reason for cultivation. The flowers are small and inconspicuous. |
📏 Size & Growth — Plant Comparison
False Dragonhead
Lemon Grass
🌱 Propagation — Comparing Plant Growth
False Dragonhead
Methods: Division, Seed, Stem cuttings
Difficulty: Easy
Tips: Divide rhizomes in spring or fall. Stem cuttings can be taken in late spring or early summer. Seeds can be sown in spring or fall.
Lemon Grass
Methods: Division, Seed
Difficulty: Easy
Tips: Divide mature clumps in spring or summer. Ensure each division has healthy roots and shoots. Plant in well-draining soil and keep moist. Seeds can be sown indoors in early spring.
✨ Benefits & Features — Comparing Plant Value
False Dragonhead
The 'obedient' flowers can be positioned and will often stay in place. It is a late-season bloomer, providing color when many other plants are finished flowering. Its aggressive spreading habit can be both a benefit (for ground cover) and a challenge.
- ✓ Attracts pollinators to the garden.
- ✓ Provides late-season color.
- ✓ Relatively easy to grow in the right conditions.
- ✓ Can be used in cut flower arrangements.
- ✓ Adds a naturalistic touch to the landscape.
- ⚠️ Toxic to pets
Lemon Grass
Lemon Grass is known for its distinct lemon scent and flavor, which is due to the presence of citronellal and geraniol. It is a fast-growing grass that can reach impressive heights under optimal conditions. Unlike many ornamental grasses, it is primarily grown for its culinary and medicinal uses.
- ✓ Adds a unique flavor to culinary dishes
- ✓ Provides a refreshing aroma
- ✓ May have medicinal properties
- ✓ Acts as a natural insect repellent
- ✓ Enhances the aesthetic appeal of a garden or patio
- ⚠️ Toxic to pets
📅 Maintenance Schedule — Plant Care Comparison
False Dragonhead
Lemon Grass
🌞 Light Requirements
False Dragonhead
Full sun to partial shade. Requires at least 6 hours of direct sunlight for optimal flowering.
Low light tolerant: ❌ No
Lemon Grass
Full sun (at least 6-8 hours of direct sunlight daily)
Low light tolerant: ❌ No
💧 Watering Needs
False Dragonhead
Water deeply when the top inch of soil feels dry. Avoid overwatering, which can lead to root rot. Signs of underwatering include wilting leaves, while overwatering can cause yellowing leaves and a soggy soil.
Lemon Grass
Keep the soil consistently moist, but not waterlogged. Allow the top inch of soil to dry out slightly between waterings. Overwatering can lead to root rot, while underwatering will cause the leaves to dry out and turn brown. Ensure good drainage.
🌡️ Temperature & Humidity
False Dragonhead
Temperature: 15-27°C
Humidity: 30-50%
Lemon Grass
Temperature: 18-30°C
Humidity: 40-60%
🤔 Which Plant Is Right For You?
False Dragonhead
Physostegia virginianaGardeners looking for a late-season blooming perennial to attract pollinators in a sunny location.
✅ Choose This Plant If...
- You want a late-season bloomer for your garden.
- You want to attract butterflies and hummingbirds.
- You have a sunny location with well-drained soil.
- You are prepared to manage its aggressive spreading habit.
- You enjoy the unique 'obedient' characteristic of the flowers.
❌ Skip This Plant If...
- You have limited space in your garden due to its aggressive spreading.
- You are looking for a low-maintenance plant.
- You have pets that might ingest it.
- You want a plant suitable for indoor growing.
Lemon Grass
Cymbopogon citratusExperienced gardeners who can provide ample sunlight and manage its growth.
✅ Choose This Plant If...
- You want a fragrant herb for cooking and teas
- You have a sunny outdoor space
- You enjoy the challenge of growing plants that require specific conditions
- You want a natural insect repellent
- You are interested in the potential health benefits of Lemon Grass
❌ Skip This Plant If...
- You have pets that may ingest it
- You lack a very sunny location
- You don't want to deal with a plant that spreads via rhizomes
🎯 Quick Verdict
⚡ Key Differences Between These Plants
Both plants have similar basic care requirements but differ in appearance and specific needs. Compare plants carefully to find the best fit for your space.
💡 Pro Tips For Comparing These Plants
False Dragonhead Care Tips
False Dragonhead is primarily an outdoor plant and is challenging to grow indoors due to its high light requirements and aggressive spreading habit. It needs full sun and well-drained soil. Indoor cultivation is not recommended.
- Plant in full sun for best flowering.
- Divide plants every 2-3 years to control spread and rejuvenate growth.
- Water deeply but infrequently, allowing the soil to dry slightly between waterings.
- Monitor for powdery mildew and rust, and treat promptly.
- Use barriers or containers to restrict its aggressive spreading.
Lemon Grass Care Tips
Lemon Grass is primarily an outdoor plant that requires full sun and consistent moisture. Growing it indoors can be challenging due to its high light requirements. It also spreads via rhizomes, so it may outgrow its container quickly. Regular division and repotting are necessary.
- Provide at least 6-8 hours of direct sunlight daily
- Ensure well-draining soil to prevent root rot
- Water deeply when the top inch of soil is dry
- Fertilize regularly during the growing season
- Divide the plant every 1-2 years to control its spread
⚠️ Common Problems & Solutions — Plant Care Comparison
False Dragonhead
Lemon Grass
❓ Frequently Asked Questions — Comparing These Plants
False Dragonhead
What are the light requirements for False Dragonhead?
False Dragonhead requires a minimum of six hours of direct sunlight daily for optimal growth and abundant flowering. A location with full sun is ideal, but it can tolerate partial shade, especially in hotter climates. In areas with intense afternoon sun, providing some afternoon shade can prevent leaf scorch. Insufficient light can lead to leggy growth, reduced flowering, and weaker stems. When planting, consider the amount of sunlight the area receives throughout the day. If growing indoors, place the plant near a sunny window, preferably south-facing. Rotate the plant regularly to ensure even light exposure on all sides. Supplemental lighting may be necessary during winter months or in areas with limited sunlight.
How do I care for False Dragonhead?
False Dragonhead thrives in full sun to partial shade, requiring at least 6 hours of sunlight daily for optimal blooming. Plant in well-draining soil that is consistently moist, but not waterlogged. Water deeply when the top inch of soil feels dry. Fertilize in spring with a balanced fertilizer to encourage healthy growth and abundant blooms. Deadhead spent flowers regularly to promote continuous blooming and prevent self-seeding, which can be aggressive in some cultivars. Divide clumps every 2-3 years in spring or fall to maintain vigor and prevent overcrowding. Provide support for taller varieties to prevent them from flopping over. Monitor for pests such as aphids and spider mites, and treat as needed. Prune back stems in late fall or early spring to prepare for the next growing season. Provide adequate air circulation to prevent fungal diseases. Amend heavy clay soils with organic matter to improve drainage.
How do I propagate False Dragonhead?
False Dragonhead can be easily propagated by division, stem cuttings, or seeds.
Lemon Grass
What are the light requirements for Lemon Grass?
Lemon Grass requires at least 6 hours of bright, indirect sunlight daily. Direct sunlight can scorch the leaves, so it’s best to place it near an east- or west-facing window where it receives filtered light. If you don’t have enough natural light, you can supplement with a grow light. Rotate the plant regularly to ensure even growth on all sides. Inadequate light can lead to leggy growth and reduced essential oil production, affecting the plant’s fragrance. Avoid placing Lemon Grass in a dark or shaded area.
How do I care for Lemon Grass?
Lemon Grass thrives in bright, indirect sunlight and requires well-draining soil. Water regularly, keeping the soil consistently moist but not waterlogged. During the growing season (spring and summer), fertilize monthly with a balanced liquid fertilizer. Prune regularly to maintain shape and encourage new growth. Lemon Grass prefers warm temperatures and high humidity; consider using a humidifier or placing the plant on a pebble tray filled with water. Repot annually in the spring to provide fresh soil and space for growth. Protect from frost and cold temperatures, as it is not cold-hardy. Monitor for pests such as aphids or spider mites and treat accordingly.
How do I propagate Lemon Grass?
Lemon Grass can be easily propagated through division, stem cuttings, or air layering. For division, carefully separate the plant into smaller clumps, ensuring each clump has healthy roots. For stem cuttings, take a 4-6 inch cutting from a healthy stem, remove the lower leaves, and plant it in moist soil. Keep the soil consistently moist until roots develop. For air layering, make a small cut on a stem, wrap it with moist sphagnum moss, and cover with plastic wrap. Once roots develop, cut the stem below the roots and plant it in soil. Propagation is best done in the spring or summer.
Last updated: April 18, 2026 — Plant care data reviewed and verified by our editorial team.