Arborvitae vs Ornamental Onion Plant Comparison
Compare these two plants side by side — care needs, key differences, and which is right for your home.
Arborvitae
Thuja occidentalis
Thuja occidentalis, commonly known as American Arborvitae, is a coniferous evergreen tree or shrub. It typically grows outdoors to a height of 30-60 feet, forming a dense, pyramidal shape. The foliage consists of scale-like leaves arranged in flattened sprays. While valued for its use in hedges, screens, and ornamental plantings in landscapes, it is not naturally suited for indoor environments due to its high light and humidity requirements and large size. People grow it for its attractive foliage, fast growth, and tolerance of various soil conditions.
Ornamental Onion
Allium spp.
Ornamental onions are bulbous perennials grown for their showy, spherical flower heads in shades of purple, pink, white, and yellow. The foliage is typically grass-like or strap-shaped and often dies back before or during flowering. They range in size from a few inches to several feet tall, depending on the species. These plants are primarily grown outdoors in gardens and borders for their architectural interest and pollinator-attracting blooms. While some smaller varieties can be grown in containers, they are generally not suited for indoor cultivation due to their high light requirements and dormancy needs.
Quick Plant Comparison
| Feature | Arborvitae | Ornamental Onion |
|---|---|---|
| Light | Full sun to partial shade. Requires at least 6 hours of direct sunlight daily for optimal growth. | Full sun (at least 6-8 hours of direct sunlight daily) |
| Watering | Every 1-2 weeks, depending on weather and soil drainage. | Every 1-2 weeks during the growing season, less frequently during dormancy. |
| Humidity | 40-60% | 30-50% |
| Temperature | 10-24°C | 10-24°C |
| Care Level | Expert | Expert |
| Growth Rate | Moderate | Moderate |
| Max Height | Rarely grown indoors; outdoors 9-18 meters | 0.15-1.5 meters (depending on species) |
| Pet Safety | ❌ Toxic To Pets | ❌ Toxic To Pets |
| Soil | Well-draining, slightly acidic soil. A mix of loam, sand, and peat moss is suitable. | Well-draining soil, such as a mix of garden soil, sand, and compost. |
| Beginner Friendly | ❌ No | ❌ No |
| Weekly Maintenance | 30 minutes monthly (outdoor) | 5 minutes weekly during the growing season. |
🔬 Botanical Information — Comparing These Plants
Arborvitae
| Scientific Name | Thuja occidentalis |
|---|---|
| Family | Cupressaceae |
| Native To | Eastern North America |
| Also Known As | American Arborvitae, Eastern Arborvitae, White Cedar, Swamp Cedar |
| Leaves | Scale-like, flattened, and arranged in overlapping sprays. Typically bright green, but can turn bronze in winter. Aromatic when crushed. |
| Flowers | Inconspicuous flowers that are rarely seen. Primarily grown for its foliage. |
Ornamental Onion
| Scientific Name | Allium spp. |
|---|---|
| Family | Amaryllidaceae |
| Native To | Various species originate from different regions across the Northern Hemisphere, including Europe, Asia, and North America. |
| Also Known As | Ornamental Onion, Flowering Onion, Allium |
| Leaves | The leaves are typically grass-like or strap-shaped, ranging in color from green to bluish-green. They emerge from the base of the plant and often die back before or during flowering. The leaves have a characteristic onion-like scent when crushed. |
| Flowers | Ornamental onions produce showy, spherical flower heads composed of numerous small, star-shaped flowers. The flowers come in a variety of colors, including purple, pink, white, and yellow. They bloom in late spring or early summer and attract pollinators. |
📏 Size & Growth — Plant Comparison
Arborvitae
Ornamental Onion
🌱 Propagation — Comparing Plant Growth
Arborvitae
Methods: Stem cuttings, Seed
Difficulty: Moderate
Tips: Take semi-hardwood cuttings in late summer. Dip in rooting hormone and plant in well-draining soil. Keep moist and provide indirect light.
Ornamental Onion
Methods: Bulb offsets, Seed
Difficulty: Moderate
Tips: Divide bulb offsets in the fall after the foliage has died back. Sow seeds in the spring or fall.
✨ Benefits & Features — Comparing Plant Value
Arborvitae
Its dense, evergreen foliage provides year-round privacy and screening. It is relatively fast-growing compared to other evergreens. The scale-like leaves are aromatic when crushed.
- ✓ Provides privacy and screening.
- ✓ Offers year-round greenery.
- ✓ Attracts birds and wildlife.
- ✓ Relatively low-maintenance once established.
- ✓ Can be used to create formal hedges or natural screens.
- ⚠️ Toxic to pets
Ornamental Onion
Ornamental onions are known for their striking, spherical flower heads that come in a variety of colors and sizes. They are also deer-resistant and attract pollinators, making them a valuable addition to any garden. Their foliage often dies back before flowering, adding to their unique appeal.
- ✓ Attracts pollinators to the garden
- ✓ Deer-resistant, protecting other plants
- ✓ Adds unique architectural interest
- ✓ Low-maintenance once established
- ✓ Provides long-lasting blooms
- ⚠️ Toxic to pets
📅 Maintenance Schedule — Plant Care Comparison
Arborvitae
Ornamental Onion
🌞 Light Requirements
Arborvitae
Full sun to partial shade. Requires at least 6 hours of direct sunlight daily for optimal growth.
Low light tolerant: ❌ No
Ornamental Onion
Full sun (at least 6-8 hours of direct sunlight daily)
Low light tolerant: ❌ No
💧 Watering Needs
Arborvitae
Water deeply when the top inch of soil feels dry. Avoid overwatering, which can lead to root rot. In containers, ensure proper drainage. Signs of underwatering include browning foliage and drooping. Overwatering symptoms include yellowing leaves and a musty smell from the soil.
Ornamental Onion
Water thoroughly when the top inch of soil is dry during the growing season. Reduce watering after flowering and during dormancy. Overwatering can lead to bulb rot, especially in poorly draining soil. Underwatering can cause stunted growth and poor flowering.
🌡️ Temperature & Humidity
Arborvitae
Temperature: 10-24°C
Humidity: 40-60%
Ornamental Onion
Temperature: 10-24°C
Humidity: 30-50%
🤔 Which Plant Is Right For You?
Arborvitae
Thuja occidentalisLandscapers and gardeners looking for a fast-growing evergreen for hedges, screens, or ornamental plantings in outdoor settings.
✅ Choose This Plant If...
- You need a fast-growing evergreen screen or hedge for your yard.
- You want to attract birds to your garden.
- You have well-draining soil and plenty of sunlight.
- You live in a climate with cold winters and hot summers.
- You want a low-maintenance plant once established outdoors.
❌ Skip This Plant If...
- You live in an apartment or have limited outdoor space.
- You have pets that might ingest the foliage.
- You cannot provide at least 6 hours of direct sunlight daily.
- You are looking for an easy indoor plant.
Ornamental Onion
Allium spp.Gardeners looking for striking, low-maintenance plants to add architectural interest and attract pollinators to their outdoor spaces.
✅ Choose This Plant If...
- You want a deer-resistant plant for your garden.
- You want to attract pollinators like bees and butterflies to your yard.
- You appreciate unique, architectural flower shapes.
- You are looking for a low-maintenance perennial.
- You have a sunny garden space with well-draining soil.
❌ Skip This Plant If...
- You have pets that may ingest the plant.
- You lack a sunny outdoor space.
- You are looking for a plant that thrives indoors.
🎯 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
Arborvitae Care Tips
American Arborvitae is primarily an outdoor plant and is very difficult to maintain indoors due to its high light and humidity requirements. It needs full sun and well-draining soil. Indoor cultivation is not recommended.
- Plant in well-draining soil to prevent root rot.
- Water deeply during dry periods, especially in the first year.
- Prune regularly to maintain shape and density.
- Protect from heavy snow and wind in winter.
- Monitor for pests and diseases and treat promptly.
Ornamental Onion Care Tips
Ornamental onions are primarily outdoor plants that require full sun and well-draining soil. They are not well-suited for indoor cultivation due to their high light requirements and dormancy needs. Indoor growing is challenging due to providing sufficient light and managing the dormancy period.
- Plant bulbs in well-draining soil to prevent rot.
- Provide full sun for optimal flowering.
- Allow foliage to die back naturally after flowering.
- Divide bulbs every few years to prevent overcrowding.
- Avoid overwatering, especially during dormancy.
⚠️ Common Problems & Solutions — Plant Care Comparison
Arborvitae
Ornamental Onion
❓ Frequently Asked Questions — Comparing These Plants
Arborvitae
What are the light requirements for Arborvitae?
Arborvitae thrives in bright, indirect light. Direct sunlight can scorch its delicate foliage, so avoid placing it directly in front of south-facing windows. East- or west-facing windows provide optimal light conditions. If you notice the foliage becoming pale or sparse, it may indicate insufficient light. Supplement with artificial grow lights if natural light is limited, especially during winter months. Rotate the plant regularly to ensure all sides receive adequate light. Monitor the plant’s growth and adjust its position as needed to maintain healthy foliage. Insufficient light can lead to legginess and poor growth.
How do I care for Arborvitae?
Indoor Arborvitae require bright, indirect light; avoid direct sunlight, which can scorch the foliage. Water thoroughly when the top inch of soil feels dry, ensuring proper drainage to prevent root rot. Maintain moderate humidity levels; consider using a humidifier or placing the pot on a pebble tray. Fertilize sparingly during the growing season (spring and summer) with a balanced, slow-release fertilizer. Repot every 2-3 years or when the plant becomes root-bound, using a well-draining potting mix. Prune regularly to maintain shape and remove any dead or yellowing foliage. Provide adequate air circulation to prevent fungal diseases. Monitor for pests such as spider mites and aphids, and treat promptly with insecticidal soap. Keep the plant in a stable temperature range, avoiding extreme fluctuations. Rotate the plant occasionally to ensure even growth. Dust leaves regularly to allow for better light absorption.
How do I propagate Arborvitae?
Arborvitae can be propagated through stem cuttings or air layering.
Ornamental Onion
What are the light requirements for Ornamental Onion?
Ornamental Onions require at least 6-8 hours of direct sunlight per day to thrive and produce abundant blooms. Insufficient light can result in weak stems, fewer flowers, and overall poor growth. When grown indoors, place them near a south-facing window where they can receive maximum sunlight exposure. If natural light is limited, supplement with grow lights to ensure adequate illumination. Rotate the plant regularly to ensure even light distribution on all sides. Monitor the plant for signs of light stress, such as pale leaves or elongated stems, and adjust its position accordingly.
How do I care for Ornamental Onion?
Ornamental Onions thrive in well-draining soil and full sun. Plant bulbs in the fall for spring blooms, or in early spring for summer blooms. Water thoroughly after planting and then moderately throughout the growing season, allowing the soil to dry slightly between waterings. Fertilize in early spring with a balanced fertilizer to encourage strong growth and abundant blooms. Deadhead spent flowers to prevent seed production and encourage further blooming. In colder climates, provide winter protection by mulching around the base of the plant. Divide clumps every few years to prevent overcrowding and maintain vigor. With proper care, your Ornamental Onions will provide years of stunning floral displays. Maintain good airflow to prevent fungal diseases.
How do I propagate Ornamental Onion?
Ornamental Onions can be propagated by division, stem cuttings, or keiki (small plantlets that grow on the flower stalk).
Last updated: May 20, 2026 — Plant care data reviewed and verified by our editorial team.