Libertia: planting, growing

Botany

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The Libertia, sometimes called New Zealand Iris, is a rhizomatous perennial belonging to the Iridaceae family. Native to the grassy meadows of New Zealand, Australia, and the Chilean Andes, it is easy to acclimatise in many regions that are not too cold.

The genus Libertia comprises around twenty perennial species, including Libertia formosa and Libertia grandiflora, both hardy down to -10/-12°C. The Libertia peregrinans is more tender and will acclimatise better in our coastal regions. The Libertia ixioides has produced beautiful cultivars selected for their unique tricolour foliage, offering a wide range of variegations.

It grows moderately quickly from a rhizomatous and suckering rootstock. It forms a compact, upright clump that spreads in all directions, reaching heights of 40 cm to 1.30 m for Libertia grandiflora, with a width of about 30 to 60 cm. Cultivars are generally less vigorous than their parents and offer intermediate heights of around 30 to 40 cm. Over time, the clump thickens thanks to its rhizomes.

Libertia is an interesting perennial for its very graphic, gramineous, evergreen foliage. It consists of linear, ribbon-like, thin and narrow leaves, erect and sword-shaped towards the sky, resembling those of irises. Imbricate in a fan shape, they evoke long ribbons measuring 30 to 70 cm in length and 0.3 to 1.5 cm in width.

Botanical plates: Libertia paniculata (left), and Libertia ixioides (right)

The type species, Libertia grandiflora and Libertia ixioides, which are very similar, have produced numerous cultivars offering sumptuously variegated or subtly striped colours. If Libertia grandiflora has dark green leaves, Libertia ixioides ‘Goldfinger®’ stands out with its yellow-green foliage striped with yellow and orange. The Libertia ixioides ‘Taupo Sunset®’ and ‘Taupo Blaze®’ charm with their long, multicoloured, changing leaves that blend bronze green, yellow, and orange, taking on purple-violet, red, or brown hues in the cold.

In late spring and early summer, the plant is illuminated by a very delicate white flowering. Carried by slender stems well above the foliage clump, loose panicles of 2 to 10 immaculate white flowers appear. They consist of 3 petals and 6 sepals measuring 1.5 to 3 cm in diameter, arranged in a staggered pattern and enclosed in bracts. The centre of the corolla releases a bouquet of yellow stamens.

This highly nectariferous flowering attracts numerous foraging insects, including bees and butterflies.

It is followed by the formation of decorative fruits, dehiscent capsules that are swollen and bright yellow, turning brown-black, containing round black seeds that germinate very easily.

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Species and varieties

The Main Ones

Our Favourites

Libertia grandiflora

This is the largest of the New Zealand Irises! It will look stunning in fresh rockeries, containers, borders, cascades, streams, banks, beds, or lagoons.

• Flowering time June, July
• Height at maturity 1 m

See the full description

Libertia formosa

This is the hardiest species! Ideal for edging pathways where its exotic appearance won't go unnoticed.

• Flowering time July, August
• Height at maturity 1,20 m

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Libertia peregrinans

It stands out with foliage painted in an astonishing bronze to orange colour.

• Flowering time July, August
• Height at maturity 45 cm

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Libertia ixioides Goldfinger

This variety is distinguished by the yellow-orange colour of its foliage. Both bright and dense, it is magnificent in water gardens or when combined in perennial beds!

• Flowering time July, August
• Height at maturity 40 cm

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Libertia ixioides Taupo Sunset

A remarkably colourful cultivar, whose grass-like foliage changes with temperature and season.

• Flowering time July, August
• Height at maturity 40 cm

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Libertia ixioides Taupo Blaze

It is very ornamental due to its variegated foliage! An attractive variety in many ways!

• Flowering time July, August
• Height at maturity 40 cm

See the full description

Planting Libertia

Where to Plant It?

The New Zealand Iris is a beautiful, moderately hardy perennial. Somewhat frost-sensitive, it can withstand temperatures down to -7°C in the ground, sometimes even lower (up to 10°C), when mulched in well-drained, porous soil. It is easy to grow in the ground in regions where frosts are not too harsh. Wind and spray resistant, it makes a good plant for coastal areas, thriving in high humidity. In harsher climates, it can be planted in a pot and brought indoors for the winter.

It should be planted in full sun in any ordinary, fresh but well-drained soil, preferably fertile and humus-bearing, even if dry, and free of lime.

It will ideally settle at the edge of a water feature, on the banks of a pond, either as a solitary plant or in groups, but also along pathways. After a few years, it will gradually spread, and its silhouette will become more pronounced: ensure you provide enough space.

Libertias beautifully accompanying a Judas tree (Photo: Chuck), and Libertias grandiflora by the water’s edge (Photo: L. Enking)

When to Plant It?

Planting of Libertia is preferably done in spring, from March to April or from July to September.

How to Plant It?

In well-drained soil, Libertia will be more resistant to frost.

In the Ground

• Loosen the soil well
• Dig a hole 2 to 3 times the size of the root ball
• Add a good layer of gravel at the bottom of the hole to improve drainage
• Plant in a mixture of garden soil and a bit of compost
• Fill the hole and then lightly compact it with your foot
• Mulch around the base with wood chips and water generously at planting, then regularly during the first year

In a Pot

The substrate should be rich enough and very draining to ensure good root aeration and avoid moisture that could cause rot. Place it in a sunny location, in a large pot of at least 50 cm in diameter.

• Spread a good layer of drainage material (gravel or clay balls) at the bottom of the container
• Plant in a mixture of potting soil and slightly sandy garden soil
• Mulch around the base
• In summer, water as soon as the substrate is dry (about once a week)

→ Learn more about growing Libertia in pots in our advice sheet.

Maintenance, pruning and care

Libertia is a perennial that is easy to grow in regions where frosts are not too harsh. It is also a plant that is resistant to diseases as well as to parasitic issues.

During the first two summers, ensure it does not lack water: the root should remain cool. Once well established, it will tolerate a periodically dry soil. You will then only water in case of prolonged drought.

Cut the flower spikes at the end of flowering to prevent self-sowing and trim any damaged or wilted foliage during the season.

In very cold climates, protect the stump with a dry mulch to insulate it from severe frosts.

New Zealand irises grown in pots require more attention. Water generously during the growth period: the soil should never dry out completely nor be waterlogged.

Bring the pot indoors to protect it from frost in autumn in cold regions and reduce water supply in winter, allowing the soil to dry out between waterings.

Multiplication

Dividing clumps of Libertia allows for the multiplication of the plant, as with all perennials, the young plants tend to lose vigour over the years. Carry out in spring.

1. Using a spade, dig out clumps while avoiding damaging the roots.
2. Replant the clumps in individual pots or in the ground in a well-draining mix.
3. Fill in, firm down well, and then water regularly until growth resumes.

Associate

With its opulent, graphic foliage that remains beautiful all year round, Libertia lends itself to numerous uses; in rockeries, containers, borders of beds or paths, cascades, streams, and banks. It allows for a beautiful garden even in winter with its persistent foliage. It integrates into all contemporary gardens, wild or natural gardens, and even in water gardens, providing relief, colour, and depth throughout the four seasons. It structures the decor, adding an exotic or contemporary touch to the garden or terrace.

In a mineral and minimalist garden, it is easy to pair with Asian plants, such as Japanese Herbs, Phormium, or with grasses like Calamagrostis x acutiflora ‘Karl Foerster’, creating stunning displays of persistent foliage.

In a seaside garden, it will be perfect with Pittosporum tenuifolium ‘Tom Thumb’.

In a perennial bed, it will accompany heathers, Hostas, Lithodora, Sisyrinchium, Camassia, Crocosmia, Liatris, or even red clover.

On a not too arid slope, it will thrive alongside periwinkles and hellebores.

Clumps of libertias in a bed accompanied by poppies (Photo: L. Enking)

→ Discover more association ideas with Libertias