My bearded irises did not flower: what am I doing wrong?

Fionnuala Fallon: If it’s any consolation, my own young plants also flowered very poorly this year

Bearded iris 'Benton Susan'. Photograph: Alamy/PA

My bearded irises never flowered this year, despite the fact that I made sure to grow them in a spot where they get full sun and sharp drainage. Any tips as to what I’m doing wrong? AM, Dublin

Bearded irises are one of the perennial aristocrats of the late spring/early summer garden, producing their elaborately frilled and ruffled, delicately hued flowers on stiff, fleshy stems that emerge above the plants’ sword-shaped leaves. As you say, they need full sun and should be planted so that the plant’s fleshy rhizomes sit just above the finished soil surface, allowing them to bake and ripen in the sun. They also need a really sharply drained soil, making them a great choice to plant along the edge of a sunny path or at the foot of a south- or west-facing wall.

There are several possible explanations for your plants’ lack of flowers. One is that your irises aren’t in the ground long enough and simply need a bit more time for their fleshy root systems to get properly established before starting to bloom next year. Another is that you’ve accidentally planted the rhizomes too deeply, in which case you’ll need to use a fork or spade to gently lift the plants and then immediately replant them to a shallower depth as described above. Also bear in mind that these sun-loving perennials hate to be overshadowed or crowded out by other plants, especially in our cool, damp climate, where every hour of sunshine is of the essence. Another possible reason for the poor flowering display is if you cut away the faded foliage last year before it had fully died off (just like all bulbous species, the leaves of bearded iris should be allowed to die away naturally). This beautiful perennial also won’t thrive in a nitrogen-rich soil that’s been recently manured, as this encourages plenty of green growth at the expense of its magical flowers. Finally, after so many months of cool, damp weather, there’s always the chance that your iris flowers were eaten by slugs or snails before they had a chance to properly emerge. If it’s any consolation, my own young plants also flowered very poorly this year. Tomorrow, as the saying goes, is another day.

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