Yellow Flag (Iris Pseudacorus)

Yellow Flag | Iris Pseudacorus

A Stunning UK Native Iris for Large Ponds, Lakes and Wetland Planting

Bold Golden Yellow Flowers and Strong Architectural Foliage for Wildlife Friendly Landscapes

Yellow Flag (Iris pseudacorus) is one of the most recognisable and impressive native pond plants found throughout the UK. Producing spectacular golden yellow iris flowers above tall sword shaped foliage, this vigorous marginal plant is ideal for large ponds, lakes, natural swimming ponds, wetland restoration projects, and wildlife habitats.

Flowering from late spring into early summer, Yellow Flag Iris creates a dramatic display of bright yellow blooms that stand proudly above dense clumps of upright green foliage. The flowers are highly attractive to bees, hoverflies, and other beneficial pollinators, while the dense foliage provides valuable shelter for amphibians, dragonflies, damselflies, and aquatic insects.

As a UK native species, Iris pseudacorus plays an important role in supporting biodiversity. Its extensive root system helps stabilise pond banks and wetland margins, reducing erosion and creating important habitat for wildlife. It is particularly valuable around larger ponds and lakes where its vigorous growth can be allowed to develop naturally.

Yellow Flag thrives in consistently moist soil, bog gardens, marshland areas, and shallow water. It can be planted directly into pond margins with water depths of up to 20cm above the basket. Once established, it forms substantial clumps that provide year round structure and visual interest.

The tall, upright foliage remains attractive long after flowering has finished, adding height, texture, and movement to the waterside landscape. During autumn and winter, the foliage gradually dies back before fresh growth emerges again in spring.

Due to its vigorous growth rate and mature size, Yellow Flag is generally best suited to larger ponds, lakes, and landscaping projects rather than small ornamental garden ponds. In the right setting, however, it is one of the most rewarding marginal pond plants available.

This hardy perennial is extremely reliable throughout the UK and tolerates severe winter temperatures with ease. Once planted, it requires very little maintenance and will continue to provide colour, structure, and wildlife benefits for many years.

Please note that all parts of Iris pseudacorus are considered harmful if eaten by humans or pets.

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Key Benefits

• Beautiful golden yellow iris flowers

• UK native marginal pond plant

• Excellent for wildlife ponds and natural habitats

• Provides shelter for amphibians and insects

• Attracts bees and pollinators

• Helps stabilise pond and lake edges

• Strong architectural foliage

• Extremely hardy and reliable

• Perfect for large ponds and wetland projects

• Adds height and structure to waterside planting

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Reasons to Buy

• One of the UK’s most iconic native pond plants

• Stunning yellow flowers from late spring to summer

• Excellent for biodiversity and habitat creation

• Low maintenance once established

• Ideal for naturalistic pond and lake landscapes

• Provides year round interest through foliage and structure

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Care Instructions

Yellow Flag Iris grows best in full sun or partial shade and prefers consistently moist soil or shallow water conditions. Place the basket with the crown positioned between 0cm and 20cm below the water surface.

Divide large clumps every few years during early spring if required. This helps maintain vigour and prevents overcrowding.

After the foliage dies back in autumn, cut old leaves down to just above water level. Alternatively, leave foliage in place until early spring to provide additional winter habitat for wildlife.

Generally pest and disease free, although slugs and snails may occasionally feed on young shoots.

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Flowering Period

May to July

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Size and Growing Conditions

Height: 80cm to 120cm

Spread: Up to 1 metre

Growth Rate: Fast

Planting Depth: 0cm to 20cm

Position: Full Sun or Partial Shade

Soil: Moist, wet, boggy or shallow water conditions

Hardiness: H6 (-20°C to -15°C)

Wildlife Friendly: Yes

Pollinator Friendly: Yes

UK Native: Yes

Suitable for Small Ponds: No

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Dispatching Your Pond Plants

All of our marginal pond plants are supplied in high quality Finofil aquatic baskets using specialist aquatic compost and slow release fertiliser.

Your plant arrives ready to place directly into your pond, making installation quick and simple. Finofil baskets are manufactured in the UK using 100% recycled plastic and are designed to provide excellent root development while preventing soil loss.

Plant growth and appearance will vary throughout the seasons, with fresh growth emerging in spring and flowering occurring during the natural flowering period.