blog post - bearded irises
The Plant List (2010) cites 280 accepted species of Iris worldwide, from Bearded Irises to Siberian, Dutch, Reticulated and Flag Irises. But its the former that is often the most showy and therefore, perhaps the most popular in this country.
Bearded Irises (Iris germanica) produce fans of sword-shaped glaucous green leaves and flowers from April to June. As a rule of thumb, the smaller the height of the flower spikes, the earlier the plant will flower. The 6 ‘petals’ of an iris flower are split into two groups consisting of 3 upright ‘standards’ and 3 drooping ‘falls’. The common name bearded iris is a reference to the little tufts of hair found on the upright standards of each flower.
Bearded Irises need a sunny south facing aspect where their rhizomes can bake in the warm sun. When planting, ensure the rhizomes are almost sitting on the soil surface with the top of the roots just below soil level. Do not overcrowd irises or allow other plants to crowd them out - this will shade the rhizomes meaning fewer or no flowers. Bearded Irises set flower initials in late summer and for the maximum amount of flowers the following year, the rhizomes need to bake in the sun in August and September. For this reason, plants should be left alone at this time of year. However division of Irises is necessary every 2 years to ensure they don’t become overcrowded. Bearded Irises should be divided immediately after flowering by gently lifting plants and using a sharp knife to cut through the rhizomes. You’re aiming to keep sections of fat, first year rhizomes with healthy pairs of shoots (next years flower initials). Cut back the leaves to a ‘V’ shape and replant in their final position. Chuck out any old, withered sections of rhizome in the centre of plant.
A light mulch can be applied to beds in late autumn but contrary to my usual advice of 5-8cm minimum depth, be careful not to overdue it. Remember bearded irises won’t be happy if you cover their rhizomes especially with a warm, moist mulch as this will cause them to rot. Irises thrive in well drained, neutral to alkaline soil so mushroom compost makes a good mulch. Deadhead flowers as they go over and cut the flower stem down to the base when the whole spike has finished flowering. Old leaves can be removed from the plant b gently pulling them from the rhizome. If they come away without any resistance they are ready to go but don't tug them off harshly as you could damage the rhizome.
I love bearded irises - they are pretty low maintenance when treated right and reward you with beautiful showy flowers in late spring. They don’t take up a massive amount of room, the leaves are attractive year round and you can cut the flowers (some scented) for the vase on the dining table. Beautiful!