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How to grow irises - Iris 'Silver Edge'

How to grow iris

Learn how to grow the different types of iris, including border iris and bulb iris.

Irises are loved for their sumptuous, colourful, and beautifully marked flowers. The Iris genus comprises a wide range of types that can be grown in a variety of locations, from pond margins and damp soil to borders, banks, pots and rockeries. Iris is the name of the Greek goddess of the rainbow and, aptly, iris flowers offer a wonderful spectrum of colours. Iris flowers also have a long association with French and English royalty, thanks to the Fleur-de-Lis symbol. Grown in the right spot, irises are easy to grow and long-lived. Most iris flowers bloom in summer, apart from the earliest bulbous types, such as Iris reticulata, which flower in early spring.

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Types of iris to grow

Bearded iris flower
Bearded iris flower

Bulbous irises are lovely for bursts of seasonal colour, though their flowers last for a short time only, before they die back and return to dormancy. Popular bulbous irises include Iris danfordiae and Iris reticulata, which bloom as early as February, bearing exquisitely marked blooms on 10cm stems. Brightly coloured Dutch iris is sold as a cut flower and, when planted in gardens, blooms in summer, producing large flowers on tall, sturdy stems.

Border irises include bearded iris (Iris germanica) and Siberian iris (Iris sibirica). As their name suggests, they’re ideal for growing in borders. Bearded iris is by far the largest group and is derived from species found in Mediterranean and Middle East regions, so thrives in dry conditions. Siberian iris grow well in any reasonable soil. Both types bear showy flowers on stout, upright stems. Bearded iris is so called for the caterpillar-like line of hairs on their lower petals. Several flowers are borne on each sturdy, branched stem above clumps of sword-shaped grey-green leaves. Bearded irises are sub-divided into groups: miniature dwarf, standard dwarf, intermediate, border, miniature tall and tall.

Moisture-loving iris are hardy perennials with colourful blooms in late spring and early summer, bearing flowers on tall, stout stems above clumps of sword-shaped leaves. They need soil that stays moist and doesn’t dry out at any time of year, but particularly in summer. These iris are best for growing in the margins of ponds, and bog gardens. The most popular species of moisture-loving iris are Iris ensata, Iris laevigata and the yellow flag iris, Iris pseudacorus.


When to plant irises

Planting bulb iris in a pot
Planting bulb iris in a pot

Plant bulbous irises in autumn.

Plant border irises from late summer to autumn, or spring. Plant them so the top half of the fleshy root, or rhizome, is above ground and exposed to sun. Iris sibirica should be planted with the top of the rootball at ground level.

Plant moisture-loving iris spring, summer, or autumn.


Where to grow irises

Yellow flag iris, Iris pseudacorus
Yellow flag iris, Iris pseudacorus

Bulb iris need full sun and must have well drained soil or the bulbs can rot. Dwarf iris such as Iris reticulata, are ideal for growing in pots either outdoors, or under protection in a greenhouse or a cool well-lit room. Grow larger bulb iris in borders.

Border irises need full sun and free-draining soil, as the thick root is a water-storing device. Iris sibirica can tolerate a bit more shade than Iris germanica.

Grow moisture-loving irises in permanently damp soil, bog gardens, or shallow water at pond edges.


How to care for irises

Replanting divided bearded iris rhizomes
Replanting divided bearded iris rhizomes

Allow leaves of bulbous irises to die back naturally so the bulb can build up energy for next year. Ensure bulbs don’t get too wet, particularly in winter, which can cause rotting.

Bearded iris are long-lived but flowering declines once clumps become older and congested. Rejuvenate them by dividing and replanting the younger, outer parts of the clump in late summer, discarding the older pieces of root.

Divide large clumps of moisture-loving iris in late summer.

Advice on buying irises

  • Make sure you’re buying the right iris for your planting location. There’s no point in buying a bearded iris to grow around a pond or a moisture-loving iris for a dry, sunny border. Choose carefully and your iris will last for years
  • Irises are available to buy from garden centres but you’ll find a wider range at specialist nurseries

Where to buy irises

10 Irises to grow

Border iris:

1

Bearded iris ‘Edith Wolford’

Iris 'Edith Wolford'
Iris ‘Edith Wolford’

Iris ‘Edith Wolford’ is a bearded iris with bright yellow standards and violet, ruffled falls. It’s perfect for growing in a mixed herbaceous border or gravel garden.

H x S: 90cm x 20cm


2

Bearded iris ‘Feu du Ciel’

Iris 'Feu du Ciel'
Iris ‘Feu du Ciel’

Iris ‘Feu Du Ciel’ bears orange-yellow standards and falls with a darker orange beard, in contrast with green-grey, sword-shaped leaves.

H x S: 80cm x 20cm


3

Bearded iris ‘Wonders Never Cease’

Iris 'Wonders Never Cease'
Iris ‘Wonders Never Cease’

Iris ‘Wonders Never Cease’ bears pretty flowers with white standard petals and white-edged bronze fall petals with a bright yellow beard, on slender stems.

H x S: 80cm x 45cm

4

Siberian iris ‘Blue King’

Iris sibirica 'Blue King'
Iris sibirica ‘Blue King’

Siberian flag iris, Iris sibirica, produces small, delicate flowers and narrow, bright green foliage. Flower petals are purple with white and yellow markings. Iris sibirica ‘Blue King’ bears deep violet flowers with veined yellow throats.

H x S: 1.2m x 80cm


Bulbous iris:

5

Iris reticulata

Iris reticulata
Iris reticulata

Iris reticulata is an early flowering iris, bearing pale blue to deep violet blooms with central yellow splashes down the middle of each petal, from late winter to early spring.

H x S: 15cm x 10cm


6

Iris reticulata ‘Katharine Hodgkin’

Iris reticulata 'Katharine Hodgkin'
Iris reticulata ‘Katharine Hodgkin’

Iris reticulata ‘Katharine Hodgkin’ has larger flowers than most other dwarf irises. Each creamy white bloom is covered with distinctive blue veining.

H x S: 15cm x 10cm


7

Winter iris, Iris histrioides

Iris histrioides
Iris histrioides

Iris histrioides is a dwarf, bulbous iris bearing deep purple flowers with yellow markings, from late-winter. Perfect for winter pot displays.

H x S: 15cm x 10cm


8

Yellow flag iris

Yellow flag iris, Iris pseudacorus
Yellow flag iris, Iris pseudacorus

Yellow flag iris, Iris pseudacorus, is a vigorous water iris, typically found growing at the edges of large, sunny ponds. It bears large clumps of green leaves from which elegant, yellow flowers appear in late-spring.

H x S: 1.2m x 1m


9

Stinking iris, Iris foetidissima

Iris foetidissima
Iris foetidissima

Iris foetidissima is the perfect iris for a shady spot, particularly beneath trees, where other plants struggle. It has architectural evergreen foliage and dull purple flowers, but it comes into its own in autumn when its large seedpods split open to reveal rows of orange-red seeds that remain well into winter.

H x S: 75cm x 45cm


10

Japanese water iris, Iris ensata

Iris ensata
Iris ensata

Japanese water iris, Iris ensata, has variegated foliage and rich purple flowers. Perfect for growing at the pond edge, it will gradually spread to form a large clump.

H x S: 75cm x 50cm

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