A step-by-step guide to dividing bearded irises

ROBERT CHARLES ROBERT CHARLES ROBERT CHARLES ROBERT CHARLES ROBERT CHARLES ROBERT CHARLES

Dividing bearded irises: Step one

Dividing bearded irises: Step two

Dividing bearded irises: Step three

Dividing bearded irises: Step four

Dividing bearded irises: Step five

Dividing bearded irises: Step six

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Step 1 Bearded irises have remarkable flowers. Three downward facing petals with a beard (or frill, perhaps) down the centre and three upright petals make an interesting configuration. This is one group of plants that needs dividing about every three years or the plants start to deteriorate. This patch of bearded iris has not been touched for some years and set few flowers last spring. Timing for lifting clumps is not critical - any time after flowering through to early autumn is fine.

Step 2 Dig up the rhizomes. These are the light brown tubers near the surface of the soil. The plant stores its energy in the rhizomes. Be careful not to damage these or you will open them up to disease and rot.

Step 3 Wash the clump, if you wish, so you can see what you are doing. Sometimes the rhizomes will fall apart. Alternatively, make a clean cut to separate them. If you have a disease problem already, make sure you disinfect your knife or snips and get rid of any diseased portions. This is not necessary if it all looks perfectly healthy.

Step 4 Discard any soft, mushy or damaged growths, as seen here on the right. Unless you are trying to increase numbers, discard any small rhizomes that are less than about 4cm in length. If the original rhizome is very old or has no leaves, discard that, too. Some advice says that each rhizome only flowers once, but we have not tested this and not all sources agree on this point. The ones to replant should look like those on the left.

Step 5 Cut the leaves back to about 15cm in length. This reduces the stress on the plant as it re- establishes its roots. Replant by spreading the roots and nestling the rhizomes just into the surface of the soil. Never bury the rhizome deeply - make sure that, if it is covered, it is only by a centimetre or two. Good drainage is critical and full sun is recommended.

Step 6 Bearded irises do not need much fertiliser. We prefer to rely on the light boost that compost gives rather than general fertiliser. Irises prefer alkaline soils, but we have never worried about adding lime and ours still flower well. Dividing is more important than adding lime. Do not let the newly replanted divisions dry out too much if we get a dry spell before autumn.