Kohlrabi vs New Zealand Flax Plant Comparison
Compare these two plants side by side — care needs, key differences, and which is right for your home.
Kohlrabi
Brassica oleracea var. gongylodes
Kohlrabi is a biennial vegetable cultivated as an annual, known for its swollen, globular stem that grows above ground. It features a crisp, mild flavor similar to a turnip or cabbage. The plant has long-stalked leaves emerging from the bulbous stem. It is primarily grown outdoors in gardens and farms for its edible stem and leaves. While it can be started indoors, it requires full sun and ample space to thrive, making it challenging to grow to maturity indoors. People grow kohlrabi for its unique texture and flavor in salads, stir-fries, and other culinary applications.
New Zealand Flax
Phormium tenax
Phormium tenax, commonly known as New Zealand Flax, is a large, evergreen perennial plant forming clumps of long, strap-like leaves. It's native to New Zealand and is primarily an outdoor plant, valued for its dramatic architectural form and fiber production. The leaves can grow up to 3 meters long and come in various colors, from green to bronze and variegated forms. While it can be grown indoors, it requires very bright light and significant space, making it challenging for most homes. People grow it for its striking appearance in gardens and landscapes.
Quick Plant Comparison
| Feature | Kohlrabi | New Zealand Flax |
|---|---|---|
| Light | Full sun (at least 6 hours of direct sunlight daily) | Full sun to partial shade outdoors. Indoors, requires extremely bright, direct sunlight for several hours daily. |
| Watering | Every 2-3 days outdoors, depending on weather conditions | Every 1-2 weeks, depending on light and temperature. Less frequent in winter. |
| Humidity | 40-60% | 30-50% |
| Temperature | 15-24°C | 10-27°C |
| Care Level | Expert | Expert |
| Growth Rate | Moderate | Moderate |
| Max Height | 30-45 cm (outdoors) | 1-2 meters indoors (much larger outdoors) |
| Pet Safety | ✅ Safe | ❌ Toxic To Pets |
| Soil | Well-draining, fertile soil rich in organic matter | Well-draining soil is crucial. A mix of potting soil, sand, and perlite is suitable. |
| Beginner Friendly | ❌ No | ❌ No |
| Weekly Maintenance | 15-30 minutes weekly | 30 minutes weekly |
🔬 Botanical Information — Comparing These Plants
Kohlrabi
| Scientific Name | Brassica oleracea var. gongylodes |
|---|---|
| Family | Brassicaceae |
| Native To | Northern Europe |
| Also Known As | German turnip, turnip cabbage |
| Leaves | The leaves of kohlrabi are typically bluish-green, broad, and have a slightly waxy texture. They are attached to the stem by long, slender stalks. The leaf shape can vary, but they are generally oval or rounded with slightly serrated edges. |
| Flowers | Kohlrabi will flower in its second year if allowed to overwinter. The flowers are typical of the Brassica family, with four petals arranged in a cross shape, usually yellow or white. Flowering is rare when grown as an annual for its bulb. |
New Zealand Flax
| Scientific Name | Phormium tenax |
|---|---|
| Family | Asphodelaceae |
| Native To | New Zealand |
| Also Known As | New Zealand Flax, Harakeke |
| Leaves | Long, strap-like leaves that can grow up to 3 meters long. The leaves are stiff and leathery, with a smooth texture. Colors range from green to bronze, red, and variegated forms. |
| Flowers | Rarely flowers indoors. Outdoors, it produces tall flower stalks with reddish-brown flowers in summer. |
📏 Size & Growth — Plant Comparison
Kohlrabi
New Zealand Flax
🌱 Propagation — Comparing Plant Growth
Kohlrabi
Methods: Seed
Difficulty: Easy
Tips: Start seeds indoors 4-6 weeks before the last frost or direct sow outdoors after the last frost. Keep soil consistently moist.
New Zealand Flax
Methods: Division, Seed
Difficulty: Moderate
Tips: Division is best done in spring. Carefully separate the rhizomes and plant them in well-draining soil. Seeds can be sown in spring after soaking them in water for 24 hours.
✨ Benefits & Features — Comparing Plant Value
Kohlrabi
Kohlrabi is unique due to its edible, swollen stem that grows above ground, unlike root vegetables. Its mild flavor and crisp texture make it a versatile ingredient in various dishes. The plant also offers edible leaves, adding to its appeal.
- ✓ Provides fresh, nutritious vegetables
- ✓ Adds visual interest to the garden
- ✓ Encourages healthy eating habits
- ✓ Offers a unique culinary ingredient
- ✓ Supports sustainable living
- 🐾 Pet Safe
New Zealand Flax
New Zealand Flax is known for its long, strap-like leaves and dramatic architectural form. It is a versatile plant that can be used in a variety of landscaping applications. The plant's fibers were traditionally used by the Maori people for weaving.
- ✓ Adds a dramatic architectural element to indoor or outdoor spaces.
- ✓ Provides a bold statement with its striking foliage.
- ✓ Offers a connection to New Zealand's natural heritage.
- ✓ Can be used as a privacy screen outdoors.
- ✓ Relatively low-maintenance once established (outdoors).
- ⚠️ Toxic to pets
📅 Maintenance Schedule — Plant Care Comparison
Kohlrabi
New Zealand Flax
🌞 Light Requirements
Kohlrabi
Full sun (at least 6 hours of direct sunlight daily)
Low light tolerant: ❌ No
New Zealand Flax
Full sun to partial shade outdoors. Indoors, requires extremely bright, direct sunlight for several hours daily.
Low light tolerant: ❌ No
💧 Watering Needs
Kohlrabi
Water deeply when the top inch of soil feels dry. Avoid overwatering, which can lead to rot. Consistent moisture is important for bulb development. Signs of underwatering include wilting leaves and stunted growth. Overwatering can cause yellowing leaves and a mushy stem.
New Zealand Flax
Water thoroughly when the top inch of soil is dry. Overwatering can lead to root rot, especially indoors. Allow the soil to dry slightly between waterings. Signs of underwatering include drooping leaves; overwatering includes yellowing leaves and a soggy soil.
🌡️ Temperature & Humidity
Kohlrabi
Temperature: 15-24°C
Humidity: 40-60%
New Zealand Flax
Temperature: 10-27°C
Humidity: 30-50%
🤔 Which Plant Is Right For You?
Kohlrabi
Brassica oleracea var. gongylodesGardeners looking for a unique and nutritious vegetable to grow outdoors.
✅ Choose This Plant If...
- You have a sunny garden space.
- You enjoy growing your own vegetables.
- You want a unique and nutritious addition to your diet.
- You are looking for a relatively fast-growing crop.
- You enjoy the taste of cabbage and turnips.
❌ Skip This Plant If...
- You lack sufficient outdoor space.
- You cannot provide at least 6 hours of direct sunlight daily.
- You are looking for a low-maintenance indoor plant.
New Zealand Flax
Phormium tenaxExperienced plant enthusiasts with very bright indoor spaces or those looking for a striking outdoor plant.
✅ Choose This Plant If...
- You have a very bright, sunny indoor space and want a statement plant.
- You live in a mild climate and want a striking evergreen for your garden.
- You appreciate plants with architectural form and interesting foliage.
- You are interested in the traditional uses of plants and their cultural significance.
- You are an experienced plant owner looking for a challenging indoor plant project.
❌ Skip This Plant If...
- You have limited indoor space.
- You have pets that might ingest the plant.
- You struggle to provide bright, direct sunlight.
- You are a beginner plant owner.
- You tend to overwater your plants.
🎯 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
Kohlrabi Care Tips
Kohlrabi is primarily an outdoor plant that requires full sun and consistent moisture. Growing it indoors is challenging due to the high light requirements and space needed for bulb development. It's best suited for experienced gardeners with outdoor space.
- Start seeds indoors for an earlier harvest.
- Ensure well-draining soil to prevent rot.
- Provide consistent moisture for optimal bulb development.
- Fertilize regularly during the growing season.
- Protect from pests like aphids and cabbage worms.
New Zealand Flax Care Tips
New Zealand Flax is primarily an outdoor plant and requires expert care to thrive indoors. It needs very bright light, well-draining soil, and careful watering to avoid root rot. Due to its size and light requirements, it's not well-suited for most indoor environments.
- Provide at least 6 hours of direct sunlight daily indoors.
- Ensure excellent drainage to prevent root rot.
- Water deeply but infrequently, allowing the soil to dry slightly between waterings.
- Fertilize regularly during the growing season.
- Monitor for pests and diseases and treat promptly.
⚠️ Common Problems & Solutions — Plant Care Comparison
Kohlrabi
New Zealand Flax
❓ Frequently Asked Questions — Comparing These Plants
Kohlrabi
What are the light requirements for Kohlrabi?
Kohlrabi thrives in full sun, requiring at least 6 hours of direct sunlight per day to produce healthy bulbs. Insufficient light can lead to leggy growth and smaller, less flavorful bulbs. In hotter climates, providing some afternoon shade can prevent the plant from bolting (prematurely going to seed). When growing indoors, place Kohlrabi near a south-facing window or use grow lights to supplement natural light. Rotate the plants regularly to ensure even light exposure on all sides. Monitor the leaves for signs of insufficient light, such as pale color or elongated stems, and adjust the light accordingly.
How do I care for Kohlrabi?
Kohlrabi requires well-draining soil rich in organic matter. Plant seeds directly in the garden or start indoors 4-6 weeks before the last frost. Space plants 6-8 inches apart in rows 12-18 inches apart. Water regularly, keeping the soil consistently moist but not waterlogged. Fertilize every 2-3 weeks with a balanced fertilizer, paying attention to potassium levels to promote strong bulb development. Kohlrabi prefers full sun but can tolerate partial shade, especially in warmer climates. Harvest when the bulb reaches 2-3 inches in diameter for the best flavor and texture. Protect from pests like cabbage worms and aphids with appropriate organic pest control methods. Rotate crops annually to prevent soilborne diseases.
How do I propagate Kohlrabi?
Kohlrabi is typically propagated by seed, but it is possible to propagate it through vegetative methods, although less common.
New Zealand Flax
What are the light requirements for New Zealand Flax?
New Zealand Flax prefers bright, indirect light. Placing it near an east-facing window is ideal, as it receives gentle morning sun. A south-facing window can also work, but be sure to filter the light with a sheer curtain to prevent leaf burn. Insufficient light can lead to leggy growth and faded leaf colors. Rotate the plant regularly to ensure even light exposure on all sides. If natural light is limited, supplement with grow lights to maintain healthy growth. Consider the intensity and duration of light, aiming for at least 6 hours of bright, indirect light per day. Consistent light exposure is crucial for vibrant foliage.
How do I care for New Zealand Flax?
New Zealand Flax thrives with bright, indirect light; avoid direct sunlight to prevent scorching. Water thoroughly when the top inch of soil feels dry, ensuring good drainage to prevent root rot. Maintain moderate humidity levels. Ideal temperatures range from 60-80°F (15-27°C). Fertilize during the growing season (spring and summer) with a balanced liquid fertilizer diluted to half strength every 4-6 weeks. Repot every 2-3 years or when the plant becomes root-bound, using a well-draining potting mix. Prune dead or damaged leaves regularly to maintain appearance and promote healthy growth. Provide adequate ventilation to prevent fungal diseases. Monitor for pests such as spider mites and treat promptly. Stable conditions are key to success.
How do I propagate New Zealand Flax?
New Zealand Flax can be propagated through stem cuttings or division. For stem cuttings, take a healthy cutting from a mature plant, ensuring it has at least one node. Remove the lower leaves and place the cutting in water or directly into a well-draining potting mix. Keep the cutting moist and in a warm, bright location until roots develop. For division, carefully separate the root ball of a mature plant into smaller sections, ensuring each section has healthy roots and foliage. Plant each section in its own pot with well-draining potting mix. Water thoroughly and keep in a warm, bright location. Propagation is best done in spring or summer. Use rooting hormone to improve success rates.
Last updated: April 21, 2026 — Plant care data reviewed and verified by our editorial team.