The Complete Guide to Flax Varieties for New Zealand Gardens

Flax - or Phormium, if we're being proper about it - is absolutely iconic in New Zealand gardens. Walk down any street and you'll spot it: dramatic sword-like leaves creating structure, adding height, or providing bold colour. But here's the thing - not all flax is created equal, and choosing the wrong variety for your space is a recipe for frustration. Let's sort out which flax actually suits your garden, because there's a world of difference between varieties.

You've probably seen massive flax specimens that have outgrown their spots, dominating entire garden beds and requiring constant cutting back. That's usually someone who planted Phormium tenax when they needed something compact. Or perhaps you've noticed flax that looks permanently bedraggled and sad - probably a tender variety struggling in cold conditions. Getting the right flax for the right spot makes all the difference between a garden feature and a garden problem.

Understanding the Two Main Species

Before we dive into cultivars, let's clarify the basics. There are two native flax species, and they're rather different characters.

Phormium tenax (Harakeke or Swamp Flax): This is the big one - the proper architectural specimen that can reach 2-3 metres tall. It evolved in swamps and wetlands, so it tolerates wet conditions brilliantly. The leaves are broader and more upright than cookianum. It's tougher, harder, and better for exposed sites. This is what Māori used traditionally for weaving - those strong, fibrous leaves are genuinely tough.

If you've got space, wet soil, or exposed conditions, tenax is your plant. If you've got a small garden, it's probably not - unless you fancy spending your weekends cutting it back.

Phormium cookianum (Wharariki or Mountain Flax): Smaller, more graceful, with narrower leaves that arch attractively rather than standing bolt upright. Typically reaches 1-1.5 metres tall. Evolved in drier, more mountainous areas, so it's less tolerant of wet feet but handles drier conditions better. The leaves are more flexible - you can bend them without snapping, unlike tenax which can be quite rigid.

For most home gardens, cookianum or its hybrids are more appropriate. The scale is manageable and the arching habit is actually rather lovely.

Large Flax Varieties (2+ Metres)

These are statement plants for larger gardens, farm settings, or where you need serious impact. Plant them and mean it - they'll dominate.

Phormium tenax (Straight Species): The classic green swamp flax. Grows 2-3 metres tall and wide. Absolutely indestructible - handles coastal winds, wet soils, drought once established, and basically anything you throw at it. Bronze flower stems can reach 4 metres. Brilliant for shelter belts, large borders, or feature plantings where you want presence. Not subtle, but genuinely magnificent at full size. Full sun to part shade. Tolerates wet soil.

Phormium tenax 'Purpureum': Similar size to the species but with burgundy-purple foliage. Stunning impact, especially with evening light behind it. Equally tough and adaptable. Use where you want drama and have the space to accommodate it. Tends to look its best in full sun where the colour deepens. Tolerates wet conditions.

Phormium 'Sundowner': Large hybrid reaching 2 metres. Bronze-green leaves with pink-red margins - the variegation is genuinely stunning. One of the most popular large cultivars because the colour is so distinctive. Slightly less tolerant of wet feet than straight tenax, prefers reasonable drainage. Full sun for best colour. Hardy to about -10°C.

Phormium 'Platts Black': Dark burgundy foliage that's almost black in certain lights. Reaches about 2 metres. The darkest of the large varieties - brilliant for creating contrast or moody drama. Full sun to maintain colour; in shade it becomes more green-burgundy. Reasonably hardy.

Medium Flax Varieties (1-1.5 Metres)

This size range works in many home gardens. Still provides presence and structure without overwhelming the space.

Phormium 'Yellow Wave': Bright yellow-green foliage with lime margins. Reaches about 1.2-1.5 metres. Absolutely brilliant for bringing light to gardens. The colour is cheerful without being garish. Arching habit from its cookianum parentage. Excellent drainage essential - this one really doesn't like wet feet. Full sun to part shade. Hardy to about -8°C.

Phormium 'Apricot Queen': Olive-green leaves with apricot-orange margins. Reaches 1-1.5 metres. The colour combination is subtle and sophisticated - lovely in autumn light. Arching habit. Prefers good drainage. Full sun brings out the best colouring. Reasonably hardy to about -8°C.

Phormium 'Bronze Baby': Despite the name, this isn't particularly small - reaches about 1-1.2 metres. Bronze-red foliage provides year-round colour. More upright than arching. Reasonably tough and adaptable. Full sun to part shade. Hardy to about -10°C.

Phormium 'Duet': Cream and green striped foliage reaches about 1.2 metres. The variegation is clean and crisp - looks smart in formal settings or modern gardens. More upright habit. Prefers good drainage. Full sun to light shade. Moderately hardy to about -8°C.

Phormium 'Jester': Pink, bronze, and green striped foliage - genuinely striking colouration. Reaches 1-1.2 metres. The pink tones are most intense in full sun and cool weather. Excellent drainage essential. This one can sulk in heavy, wet soils. Full sun. Moderately hardy to about -5°C - one of the more tender varieties.

Compact Flax Varieties (Under 1 Metre)

These are the varieties that actually work in most home gardens. They provide flax's structural qualities without the overwhelming size.

Phormium 'Emerald Gem': Dark green upright foliage stays neat at just 50-60cm. One of the best compact varieties for general garden use. Unfussy about conditions within reason - handles sun to part shade, reasonable soils, and stays truly compact without needing cutting back. Hardy to about -10°C. Brilliant for borders, pots, or repeated plantings.

Phormium 'Tom Thumb': Bronze-burgundy foliage forms neat clumps about 50cm tall. More arching than 'Emerald Gem'. Popular for good reason - the colour is rich, the size is manageable, and it's relatively unfussy. Full sun for best colour. Good drainage preferred. Hardy to about -8°C.

Phormium 'Pink Stripe': Green leaves with pink margins stay compact at about 50-60cm. The pink is subtle rather than bright - quite sophisticated. More upright than arching. Prefers good drainage and full sun. One of the more tender compacts - hardy to about -5°C. Better suited to warmer regions or very sheltered spots.

Phormium 'Jack Spratt': Extremely narrow, almost grass-like bronze leaves create unique texture. Stays very compact at just 40-50cm. Completely different effect to typical flax - much softer appearance. Excellent drainage essential - this one will rot in heavy, wet soils. Full sun to part shade. Hardy to about -8°C.

Phormium 'Amazing Red': Burgundy-red foliage with bronze tones. Compact at 60-70cm. Strong colour throughout the year, intensifying in cold weather. More upright than arching. Reasonable drainage needed. Full sun. Hardy to about -8°C. Brilliant for pots or bold colour statements.

Variegated Beauties

Variegated flax brings light and lift to gardens. The colour breaks provide year-round interest.

Phormium 'Cream Delight': Green and cream striped foliage reaches about 1 metre. One of the best variegated varieties - the contrast is clean, the plant is relatively tough, and it doesn't burn as easily as some variegates in strong sun. Part shade to full sun. Good drainage. Hardy to about -8°C.

Phormium 'Maori Sunrise': Bronze-pink and olive striped foliage reaches about 80cm. The colouring is complex and changes with seasons - pinks intensify in cold weather. Absolutely stunning but needs good drainage and isn't particularly hardy - about -5°C. Best in warmer regions or very sheltered spots. Full sun.

Phormium 'Rainbow Queen': Pink, bronze, and yellow striped foliage reaches about 1-1.2 metres. Colour carnival - brilliant for modern gardens or where you want something bold. More upright. Good drainage essential. Full sun. Moderately hardy to about -6°C.

Phormium 'Tricolor': Green, cream, and pink striped foliage reaches about 80cm-1 metre. Classic variegated variety that's been around for years. The pink edges are most intense in cold weather. Good drainage. Full sun to part shade. Hardy to about -7°C.

Choosing the Right Flax for Your Site

Wet soil or boggy conditions: Choose Phormium tenax (green or purple). These evolved in swamps and actually enjoy wet feet. Most cultivars and cookianum varieties will rot in consistently wet soils.

Dry, well-drained soil: Choose cookianum varieties or hybrids with arching habits. 'Yellow Wave', 'Apricot Queen', and most variegated varieties prefer good drainage. Avoid tenax in very dry soils - it prefers more moisture.

Coastal exposure: Tenax varieties and larger hybrids like 'Sundowner' handle coastal winds and salt spray brilliantly. Smaller, more tender varieties can get damaged by salt-laden winds.

Frost-prone areas: Stick with hardier varieties - tenax species, 'Purpureum', 'Bronze Baby', 'Emerald Gem'. Avoid tender cultivars like 'Jester', 'Pink Stripe', and 'Maori Sunrise' unless you're prepared for potential frost damage.

Small gardens: Choose genuinely compact varieties - 'Emerald Gem', 'Tom Thumb', 'Jack Spratt'. Resist the temptation to plant large varieties intending to "keep them trimmed" - you'll spend your life cutting them back.

Pots: Compact varieties work brilliantly in containers. 'Emerald Gem', 'Tom Thumb', and 'Amazing Red' all tolerate container culture well. Large varieties become pot-bound quickly and need constant root pruning.

Planting and Establishing Flax

Site preparation: Most flax prefers full sun, though larger varieties tolerate part shade. Dig a hole twice the width of the pot but the same depth. Work compost into heavy clay soils to improve drainage, especially for cultivars that don't like wet feet.

Planting: Remove the plant from its pot and gently tease out any circling roots. Plant at the same depth as it was in the pot - not deeper. Firm soil around roots and water thoroughly. Mulch around the plant but keep mulch away from the crown to prevent rot.

First year watering: Even drought-tolerant varieties need consistent watering for their first summer whilst establishing. Water deeply once or twice a week depending on conditions. By the second year, most established flax is remarkably drought-tolerant.

Feeding: Flax needs minimal feeding. A light application of general fertiliser in spring is sufficient. Over-feeding, especially with high-nitrogen fertilisers, produces soft, lush growth that flops rather than stands upright. Lean conditions keep growth compact and sturdy.

Maintenance and Problem Solving

Removing dead leaves: Flax naturally sheds older outer leaves. These become brown and tatty-looking. Pull them downward and outward - they should come away cleanly if truly dead. Some people pull them weekly, others once a season. It's largely about how tidy you want things to look.

Pruning: If your flax has outgrown its space, you have two options. First, remove entire outer fans (leaf sections) at the base - this reduces overall size whilst maintaining natural appearance. Second, cut the entire plant back to about 15cm above ground in early spring. It will reshoot, though it takes 1-2 years to look properly established again. This is drastic but sometimes necessary.

Flower spikes: Flax produces tall flower spikes with tubular red or yellow flowers. These are brilliant for native birds but do sap plant energy. After flowering, cut spikes down at the base if you want plants to stay more compact. Leave them if you value the bird attraction.

Flax weevil: This beetle's larvae bore into leaf bases and can damage or kill plants. Look for notches chewed in leaves or stunted growth. Remove badly affected fans. In severe cases, use a systemic insecticide labelled for flax weevil. Good garden hygiene (removing dead leaves regularly) reduces hiding places.

Yellowing leaves: Usually indicates too much water in poorly-draining soil, especially for varieties that prefer dry conditions. Improve drainage or choose more moisture-tolerant varieties. Occasionally it indicates potassium deficiency - a light application of potash can help.

Tip burn: Leaf tips turn brown and crispy. This is usually from dry soil (water more), cold damage (choose hardier varieties), or salt burn in coastal areas (rinse foliage occasionally with fresh water). Sometimes it's simply natural aging in older leaves.

Design Uses for Different Flax Types

Focal points: Use large, dramatic varieties like 'Sundowner' or 'Platts Black' as solo specimens. Position them where they'll be viewed from multiple angles. Evening light behind them is particularly effective.

Repeated rhythm: Use compact varieties like 'Emerald Gem' or 'Tom Thumb' as repeated elements - perhaps five planted at intervals along a border. This creates rhythm and cohesion whilst maintaining manageable scale.

Contrast plantings: Pair upright flax with mounding or spreading plants. The vertical swords contrast beautifully with rounded Coprosma or flowing grasses. Or combine variegated flax with solid green or burgundy foliage plants.

Container features: Compact varieties in large pots make excellent feature elements on patios or flanking doorways. Pair dark varieties like 'Tom Thumb' with silver containers, or variegated varieties with dark pots.

Mass plantings: In larger gardens, mass plantings of single varieties create impact. Five or seven 'Bronze Baby' planted together makes a bold statement. Don't mix too many varieties in mass plantings - it becomes messy rather than impactful.

Screening: Large tenax varieties planted 1-1.5 metres apart create effective screens relatively quickly. They're particularly good for coastal screening where many plants struggle.

Regional Considerations

Auckland and Northland: Your warm, humid conditions suit most flax varieties. You can grow tender cultivars like 'Jester' and 'Maori Sunrise' without worry. Ensure good drainage - humidity combined with poor drainage can cause fungal issues.

Wellington: Wind is your main challenge. Stick with tougher varieties - tenax species, 'Sundowner', 'Bronze Baby'. Compact varieties can get shredded in really exposed sites. Your cooler conditions mean tender varieties may struggle.

Canterbury and Otago: Cold winters mean choosing hardy varieties is essential. Tenax species, 'Purpureum', 'Bronze Baby', and 'Emerald Gem' all handle frosts well. Avoid tender cultivars unless in very sheltered city gardens. Your hot, dry summers suit most flax once established.

Coastal anywhere: Salt tolerance is key. Tenax varieties excel. Most hybrids tolerate coastal conditions reasonably well, though very exposed sites can damage tender varieties. Rinse salt off foliage occasionally during very dry periods.

Getting Your Flax Choice Right

The most important decision is honestly assessing your available space and choosing a variety that genuinely fits at mature size. That means compact varieties for most home gardens, medium varieties for larger borders, and large varieties only where you've truly got the room.

Consider your soil conditions - wet or dry - and choose accordingly. Factor in your climate and frost exposure. Think about the colour and how it works with surrounding plants.

Get these fundamentals right and flax becomes one of the most rewarding, lowest-maintenance structural plants you can grow. Get them wrong and you'll spend years fighting a losing battle with secateurs, trying to keep an oversized plant under control. Choose wisely, plant properly, and enjoy one of New Zealand's most spectacular garden plants.