Flowering Onion vs Pickerel Weed Plant Comparison
Compare these two plants side by side — care needs, key differences, and which is right for your home.
Flowering Onion
Allium spp.
Flowering onions, or ornamental alliums, are bulbous perennials grown for their showy, spherical flower heads composed of numerous small, star-shaped flowers. They come in various sizes and colors, ranging from white and pink to purple and deep burgundy. Most are outdoor plants, thriving in gardens and borders. While some smaller varieties can be grown in containers, they are not ideally suited for indoor environments due to their high light requirements and dormancy needs. People grow them for their striking blooms, architectural interest, and ability to attract pollinators.
Pickerel Weed
Pontederia cordata
Pickerelweed is an aquatic perennial herb typically found in shallow water habitats like ponds, marshes, and streams. It features distinctive heart-shaped leaves and a prominent flower spike that blooms in summer. The plant grows from rhizomes, forming dense colonies. While primarily an outdoor plant, it is occasionally grown in large water gardens or aquariums. It is valued for its attractive foliage and flowers, which attract pollinators and provide habitat for aquatic wildlife.
Quick Plant Comparison
| Feature | Flowering Onion | Pickerel Weed |
|---|---|---|
| Light | Full sun (at least 6-8 hours of direct sunlight per day) | Full sun to partial shade |
| Watering | Every 1-2 weeks during the growing season, less frequently during dormancy. | Daily to maintain water levels |
| Humidity | 40-60% | 60-90% |
| Temperature | 15-25°C | 15-27°C |
| Care Level | Expert | Expert |
| Growth Rate | Moderate | Fast |
| Max Height | Variable, depending on the species, but typically 30-150 cm outdoors. Indoors, expect smaller sizes if grown in containers. | 0.3-1 meter (outdoor, less in containers) |
| Pet Safety | ❌ Toxic To Pets | ❌ Toxic To Pets |
| Soil | Well-draining soil, such as a mix of potting soil, sand, and perlite. | Heavy clay soil or aquatic planting mix |
| Beginner Friendly | ❌ No | ❌ No |
| Weekly Maintenance | 10 minutes weekly during the growing season. | 30 minutes weekly (including algae control, pruning, and water level maintenance) |
🔬 Botanical Information — Comparing These Plants
Flowering Onion
| Scientific Name | Allium spp. |
|---|---|
| Family | Amaryllidaceae |
| Native To | Various species originate from different regions, including Europe, Asia, and North America. |
| Also Known As | Flowering Onion, Ornamental Onion, Allium |
| Leaves | The leaves are typically linear or strap-shaped, often with a bluish-green hue. They emerge from the base of the plant and may wither as the plant flowers. |
| Flowers | Flowering onions produce showy, spherical flower heads composed of numerous small, star-shaped flowers. The flowers come in various colors, including white, pink, purple, and burgundy. They rarely flower indoors due to light requirements. |
Pickerel Weed
| Scientific Name | Pontederia cordata |
|---|---|
| Family | Pontederiaceae |
| Native To | North America, South America |
| Also Known As | Pickerelweed, Pickerel Weed, Heartleaf Pickerelweed |
| Leaves | Heart-shaped (cordate) leaves, typically 10-25 cm long and 5-15 cm wide. The leaves are smooth, glossy green, and have prominent veins. They are attached to long petioles that emerge from the rhizomes. |
| Flowers | Produces a dense spike of small, violet-blue flowers in summer. The flowers are about 1 cm long and have six petals. They are arranged spirally around the spike and bloom sequentially from the bottom up. Rarely flowers indoors. |
📏 Size & Growth — Plant Comparison
Flowering Onion
Pickerel Weed
🌱 Propagation — Comparing Plant Growth
Flowering Onion
Methods: Bulb offsets, Seed
Difficulty: Moderate
Tips: Separate bulb offsets from the main bulb in the fall and replant them. Sow seeds in the spring after a period of cold stratification.
Pickerel Weed
Methods: Division of rhizomes, Seed
Difficulty: Easy
Tips: Divide rhizomes in spring or early summer. Ensure each division has healthy roots and shoots. Plant in aquatic soil and keep submerged in water. Seeds can be sown in shallow water in spring.
✨ Benefits & Features — Comparing Plant Value
Flowering Onion
Flowering onions are known for their distinctive spherical flower heads, which can range in size from a golf ball to a softball. They offer a unique architectural element in the garden and attract beneficial insects.
- ✓ Attracts pollinators to the garden
- ✓ Deer-resistant, protecting other plants
- ✓ Adds architectural interest with unique flower shapes
- ✓ Provides long-lasting blooms for visual appeal
- ✓ Low-maintenance once established
- ⚠️ Toxic to pets
Pickerel Weed
Pickerelweed is a native aquatic plant that provides important habitat and food sources for wildlife. Its distinctive heart-shaped leaves and purple flower spikes make it an attractive addition to water gardens. It is also known for its ability to help filter and oxygenate water.
- ✓ Provides habitat for aquatic wildlife
- ✓ Attracts pollinators such as bees and butterflies
- ✓ Helps to filter and oxygenate water in ponds and aquariums
- ✓ Adds visual interest with its unique foliage and flowers
- ✓ Contributes to a natural and balanced ecosystem in aquatic environments
- ⚠️ Toxic to pets
📅 Maintenance Schedule — Plant Care Comparison
Flowering Onion
Pickerel Weed
🌞 Light Requirements
Flowering Onion
Full sun (at least 6-8 hours of direct sunlight per day)
Low light tolerant: ❌ No
Pickerel Weed
Full sun to partial shade
Low light tolerant: ❌ No
💧 Watering Needs
Flowering Onion
Water thoroughly when the top inch of soil is dry. Avoid overwatering, which can lead to bulb rot. Reduce watering during dormancy. Signs of overwatering include yellowing leaves and a mushy bulb. Underwatering is indicated by wilting leaves and stunted growth.
Pickerel Weed
Requires consistently moist to wet conditions. If grown in a container, ensure the pot is sitting in a tray of water or submerged in a larger water feature. Overwatering is not a concern as it is an aquatic plant. Underwatering will cause the leaves to wilt and brown.
🌡️ Temperature & Humidity
Flowering Onion
Temperature: 15-25°C
Humidity: 40-60%
Pickerel Weed
Temperature: 15-27°C
Humidity: 60-90%
🤔 Which Plant Is Right For You?
Flowering Onion
Allium spp.Gardeners looking for striking, low-maintenance perennials 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
- You appreciate unique, globe-shaped flowers
- You have a sunny garden space
- You want a low-maintenance perennial that returns year after year
❌ Skip This Plant If...
- You have pets that might ingest the plant
- You don't have a sunny outdoor space
- You are looking for an easy indoor plant
Pickerel Weed
Pontederia cordataExperienced gardeners with ponds, water gardens, or large aquariums who want to add a native aquatic plant.
✅ Choose This Plant If...
- You have a pond or water garden and want a native plant.
- You want to attract pollinators and wildlife to your water feature.
- You need a plant that can tolerate consistently wet conditions.
- You appreciate the unique heart-shaped foliage and flower spikes.
- You are an experienced gardener looking for a rewarding aquatic plant challenge.
❌ Skip This Plant If...
- You do not have a suitable aquatic environment (pond, water garden, large aquarium).
- You are looking for a low-maintenance indoor plant.
- You have pets that might ingest the plant, as it is toxic to them.
🎯 Quick Verdict
⚡ Key Differences Between These Plants
Flowering Onion needs full sun (at least 6-8 hours of direct sunlight per day), while Pickerel Weed prefers full sun to partial shade.
Flowering Onion has moderate growth, while Pickerel Weed grows fast.
💡 Pro Tips For Comparing These Plants
Flowering Onion Care Tips
Flowering onions are primarily outdoor plants requiring full sun and well-draining soil. Indoor cultivation is challenging due to their high light needs and dormancy requirements. They are toxic to pets, so caution is needed if grown in areas accessible to animals. Regular watering and occasional fertilization are necessary for optimal growth.
- Plant bulbs in well-draining soil to prevent rot
- Provide full sun for optimal flowering
- Water deeply but infrequently, allowing the soil to dry out between waterings
- Fertilize in early spring and after flowering to promote bulb growth
- Remove spent flower heads to encourage bulb development
Pickerel Weed Care Tips
Pickerelweed is best suited for outdoor water gardens or large aquariums. It requires full sun and consistently wet conditions. Indoor cultivation is challenging due to the need for specialized aquatic environments and intense lighting. It is an aggressive spreader and needs containment.
- Ensure consistent water levels, especially during hot weather.
- Provide full sun for optimal flowering.
- Use aquatic plant fertilizer to promote healthy growth.
- Control algae growth to prevent it from smothering the plant.
- Protect rhizomes from freezing in colder climates.
⚠️ Common Problems & Solutions — Plant Care Comparison
Flowering Onion
Pickerel Weed
❓ Frequently Asked Questions — Comparing These Plants
Flowering Onion
What are the light requirements for Flowering Onion?
Flowering Onions need ample sunlight to produce vibrant blooms. Aim for at least 6 hours of direct sunlight per day. If growing indoors, place them near a south-facing window where they can receive the most sunlight. Insufficient light can result in weak stems, pale foliage, and a lack of flowers. If natural light is limited, supplement with grow lights to provide the necessary intensity. Rotate the plant regularly to ensure even light exposure on all sides. Consider using a light meter to measure the light intensity and adjust the plant’s position accordingly.
How do I care for Flowering Onion?
Flowering Onions thrive in well-draining soil and require full sun to partial shade for optimal growth and flowering. Water thoroughly when the top inch of soil feels dry, allowing excess water to drain away. Avoid overwatering, as this can lead to bulb rot. Fertilize during the growing season (spring and summer) with a balanced, slow-release fertilizer or a liquid feed diluted to half strength every 2-4 weeks to promote abundant blooms. Deadhead spent flowers to encourage further blooming and prevent seed production. Protect from frost in colder climates by mulching heavily or moving potted plants indoors. Repot every 2-3 years as needed, using a pot slightly larger than the previous one. Ensure good air circulation around the plants to prevent fungal diseases.
How do I propagate Flowering Onion?
Flowering Onions can be propagated through division, a relatively simple method. In the fall, after the foliage has died back, carefully dig up the bulbs. Separate the smaller bulblets from the main bulb. Replant the bulblets in well-draining soil, spacing them a few inches apart. Water thoroughly and mulch to protect them from frost. They may take a year or two to reach flowering size. Stem cuttings and keiki propagation are not applicable to Flowering Onions, as they are bulbous plants. Division is the primary method for increasing your stock of these beautiful plants. Ensure the bulblets have some roots attached for best results.
Pickerel Weed
What are the light requirements for Pickerel Weed?
Pickerel Weed thrives best in full sun, requiring at least six hours of direct sunlight daily. However, it can also tolerate partial shade, especially during the hottest part of the day. Insufficient light can lead to leggy growth, reduced flowering, and overall weaker plants.
How do I care for Pickerel Weed?
Pickerel Weed thrives in shallow water or moist soil. Plant in a pond, water garden, or a container submerged in water. Full sun to partial shade is ideal. Ensure the water is clean and well-oxygenated. Add aquatic plant fertilizer sparingly during the growing season (spring and summer). Remove dead leaves and flowers regularly.
How do I propagate Pickerel Weed?
Pickerel Weed can be easily propagated through division or cuttings.
Last updated: April 20, 2026 — Plant care data reviewed and verified by our editorial team.