Kelways Guide to Bearded Irises
Looking After your Bearded Iris
Bearded iris are easily grown plants, which will thrive in most gardens providing they have a reasonable amount of sun. In a mixed border, avoid planting ground-covering plants over the irises.
Iris Care - At a Glance
- Plant in a sunny position
- Well drained soil
- Feed in summer after flowering
- Divide every 3 years
Irises like reasonably good drainage. If you have a heavy loam or clay soil it may help to dig in some coarse grit where you intend to plant. Alternatively, why not try growing them in a raised bed? They prefer a fairly neutral soil but also do well in alkaline or chalky soil.
Like most plants irises appreciate good preparation before planting. Dig in some compost to provide nitrogen and other nutrients, and this will improve the physical condition of the soil as well. If your soil is acidic lightly fork in some lime
Planting Your Bearded Iris
Pot grown iris should be planted to the same depth as the compost level in the pot. Dwarf iris can be spaced 15-22cm (6-9”) apart and intermediate and tall bearded irises 22-30cm (9-12”) apart. Firm in well and water.
Bare rooted iris are freshly harvested and should be planted as soon as possible. Soak the rhizomes in water for about an hour first. If you can’t plant them for a few days, plunge them into a tray of moist compost. Don’t worry about any old dead roots that you see. These are spent and will soon be replaced by fresh young ones. Dig a broad and shallow hole with a trowel and plant each rhizome, spreading out its roots on either side. Fill in the hole so that the upper surface of the rhizome is at about soil level. Don’t worry too much about this, as your plant will find its own level as it becomes established.
In the spring, irises will benefit from a handful of a general granular fertilizer. A second top dressing of bone meal after flowering is also beneficial. Avoid high nitrogen liquid feeds.
Irises should be divided every 3-4 years otherwise the plants will become woody and produce fewer flower spikes. Splitting the clump is best done straight after flowering, or before the end of September. The youngest and healthiest rhizomes are on the outside of the clump. These are the pieces to replant. The old pieces of rhizome can be burnt or composted.
Bearded Iris Problems
Rhizome Rot: This may occur in the spring. It normally starts at the bottom of the stem and then travels down into the rhizome where the base of the plant becomes brown, soft and foul smelling. The affected parts should be cut away, back to clean tissue, and a fungicidal powder dusted onto the rhizome. Rhizome rot rarely kills a plant outright if the correct action is taken immediately.
Leaf spot: This may be a problem during the spring and summer, particularly after a spell of wet weather. You will see small brown spots on the leaves. They rarely do much damage but are unsightly. Affected leaves can be cut back and burnt.