This section contains only those plants which are true water irises. There are many irises (such as Iris siberica varieties, and Iris ensata/Iris kaempferi varieties), which will tolerate moist soil but which will die if placed permanently in a pond. They are therefore not true pond irises and we do not feature them here.
Iris laevigata, the Japanese water iris, is probably the most well-known pond iris. The natural wild species has large blue/purple flowers, and there are also a number of garden cultivars which have flowers in shades of blue, purple, and white, some with double blooms. Iris laevigata is smaller, has more showy blooms, and is considerably slower growing than the other water irises, making it more suitable for the average pond. However, it is also more fussy - not a difficult plant to grow, but not an easy one either. It prefers slightly acid to neutral conditions, so if you are planting straight into the ground in extremely chalky soil it is best avoided.
Iris pseudacorus, the native yellow flag iris, is probably the next most well known. It is a much larger and more vigorous plant than Iris laevigata, and not at all fussy about soil conditions. A number of garden cultivars exist in shades of yellow and white. While the natural wild species is too large for many ponds, several of the garden cultivars are smaller and more manageable.
Iris versicolor, the blue flag or American water iris, is another popular species. It is slightly larger than Iris laevigata, but more vigorous, not fussy about soil, and easier to grow. The flowers are smaller but more numerous, and there are various garden cultivars in unusual shades of pink, blue, purple, and yellow.
Iris fulva, the tawny iris or American copper iris, is less well known in the UK than any of the other species. It produces copper-red flowers that are a really unusual colour, hard to find anywhere else in the water garden. It is easy to grow, not fussy about soil, and not too tall, but has a less compact growth habit, with much more slender, arching foliage than the other irises, and many flowers on each stem. The overall look is more delicate and exotic than any of the other species. A garden cultivar exists which has pure yellow flowers ('Marvell Gold').
In recent years, a group of water irises known as Louisiana Irises have appeared in UK nurseries, since they produce really gorgeous blooms. However, although they look captivating in the plant catalogue, in our experience they invariably perform poorly in our climate. Therefore we do not currently grow any of these.
Planting depths mentioned on these pages refer to the depth of water over the crown of the plant (the depth of water over the soil level). Having less water than this does not matter, as long as the soil is not allowed to dry out. In order to get the best growth and greatest number of flowers, we recommend that you plant your irises in a sunny spot and, if they are in a pot, fertilise them once a year in spring, if you are not re-potting them that year. They are best re-potted every two to three years. Please note that irises are toxic to people and animals if ingested.