Iris germanica in the farm garden, Southern Tablelands, NSWSometimes called the common flag or German iris, Iris germanica is said to be one of the ancestors of the modern bearded irises and it is an easy-to-grow plant that will do equally well in cold inland gardens as it does in the Sydney climate. The original form is purple though there is also a white variety. Growing about 40-50 cm tall, it is often seen growing wild in abandoned country gardens. It starts flowering in winter and continues on through spring (unlike the Tall Bearded Irises, which flower in October in Sydney). It is a Mediterranean plant and grows via a rhizome that spreads to make big clumps over time. The sturdy, sword-like leaves form a fan shape. It prefers a hot, dry spot in a slightly alkaline soil with excellent drainage. The top of the rhizome should not be covered by soil. Avoid the use of animal manure near the rhizomes as this can rot them.
Iris germanica in budTo keep the irises vigorous, dig them up and divide them every three or four years in mid- to late summer, as this is when the plant goes into a state of semi-dormancy after active growth that produces new rhizomes, following its flowering in mid-spring. Once it has flowered, a rhizome will not bloom again. Discard the old withered central rhizomes and replant the healthy ones from the edge of the clump, preferably in a different position in the garden. Trim away two-thirds of the foliage, cutting about 20 cm above the rhizome - this will reduce transpiration and help the rhizome remain stable until new roots establish. The roots can also be trimmed, leaving about 5 cm. Fertilise with a slow-release or organic plant food (or rose food) in late winter and when replanting.
White Iris germanicaWater irises well in late summer and autumn but reduce watering in winter, increasing the supply of water in spring. Remove any diseased or brown leaves and dispose of in the green waste bin, not in the compost heap. Remove the flowering stems close to the ground after blooming is over to help protect the rhizome from rot.
This iris is a natural companion for other Mediterranean plants, such as perennial wallflower (Erysimum), lavenders, Artemisia, statice (Limonium) and Dianthus, which all enjoy the same growing conditions and are in bloom at the same time.