How to Grow Dutch Iris: A Guide for UK Gardeners

Dutch Iris (Iris x hollandica) are a long time favourite of ours, they have a long history of cultivation and have been a staple cut flower for decades. Their vibrant flowers – some of the richest blues and purples you can grow - pair beautifully with alliums, camassias, and ornamental grasses. Perfect for cut flower arrangements, these bulbs are easy to grow, making them an excellent choice for throwing in your garden or forcing for early spring.

How to Plant Dutch Iris Bulbs

When to Plant
The best time to plant Dutch Iris bulbs is autumn (September to November), before the first frost. This gives the bulbs time to establish roots before winter.

Where to Plant

• Choose a sunny location with well-drained soil.

• They thrive in moderately fertile soil, but heavy clay can be improved with grit or well-rotted compost.

• Although they prefer full sun, Dutch Iris will tolerate light dappled shade.

Planting Depth & Spacing

• Depth: Plant bulbs 15cm deep in the soil.

• Spacing: Allow approximately 20 bulbs per square metre for a natural look.

Planting Tips:

1. Loosen the soil and add compost if needed.

2. Place bulbs pointed side up, ensuring good contact with the soil.

3. Water well after planting to encourage root development.

Caring for Dutch Iris

Once planted, Dutch Iris require minimal care, but a few key steps will ensure healthy growth and abundant flowering.

Feeding & Watering

• Foliage appears in late winter – start feeding with a high potash fertiliser, such as liquid seaweed, to promote strong blooms.

• Water during dry spells, but avoid overwatering as bulbs dislike soggy soil.

Deadheading & Cutting Back

• After flowering, allow the foliage to die back naturally.

• Only cut leaves when they turn straw-like – this helps bulbs store energy for next year’s flowers.

Storage & Overwintering

• Dutch Iris bulbs are hardy in most parts of the UK and can be left in the ground.

• If lifting, dry them thoroughly and store in a cool, dry place before replanting in autumn.

Common Problems, Pests & Diseases

Like many garden plants, Dutch Iris can be affected by pests and diseases. Here’s how to spot and prevent issues.

1. Fungal & Bacterial Diseases

• Leaf Spot – Shows as sooty patches or brown spots with yellow margins, eventually causing the leaves to die off. Solution: Remove and destroy infected foliage.

• Ink Disease – Causes black spots on bulbs, leading to yellowing leaves. Solution: Dig out infected bulbs and avoid planting iris in the same spot for two years.

2. Slugs & Snails

These pests love munching on young iris shoots. Protect your plants by:

• Sprinkling sharp grit or crushed eggshells around the base.

• Using organic slug deterrents or copper tape.

• There are lots of ways to treat slugs, sometimes it seems like an endless task. It’s the same for all gardeners!

Dutch Iris FAQs

When do Dutch Iris bloom?

Dutch Iris typically flower in early summer (May to June), adding a burst of colour to garden borders.

Stephen says, ‘Be patient, they feel like they take for ever then suddenly they appear!’

Do Dutch Iris need full sun?

Yes, they perform best in full sun, but they will also tolerate light shade.

Do Dutch Iris need a lot of water?

They prefer well-drained soil and require watering during dry spells, but avoid waterlogging, as bulbs will rot in overly wet conditions.

Can I leave Dutch Iris bulbs in the ground year-round?

Yes, Dutch Iris are hardy and can be left in the ground over winter. Just ensure they are not in waterlogged soil.

Can I grow Dutch Iris in pots?

Absolutely! Use a well-draining potting mix, plant bulbs 15cm deep, and place the pot in a sunny location.

Are Dutch Iris toxic to pets?

Yes. Dutch Iris bulbs and foliage are toxic to dogs, cats, and humans if ingested. Always plant them out of reach of pets.