Whether you choose the iconic purple-and-yellow ‘Silver Edge’ or the more unusual pale-pink ‘Raspberry Blush’, irises are easy to grow and bring structure and staggered blooms to containers, beds and borders.
Knowing what to do with irises after flowering can make the difference between a tired clump and a spectacular display next year.
From deadheading and watering to dividing overcrowded rhizomes (the main stem of the plant that runs typically underground), a few simple jobs will help keep plants healthy once the flowers fade.
Loren Taylor, owner of Outdoor Fountain Pros, shares the essential aftercare steps to encourage irises to flower well again next year.
1. Remove faded flowers and spent stems
“After irises have finished flowering, there are a few simple steps you can take to keep them healthy and encourage more flowers next year,” says Loren.
“I recommend removing the faded flowers first. When the last flower on a stem has finished, cut the flower stem down to the foliage. This keeps the plant tidy and prevents it from using energy to produce seeds.”
Use clean, sharp secateurs and cut the spent flower stalk back without damaging the surrounding leaves.
2. Leave healthy foliage in place
Do not cut back healthy green leaves immediately after flowering, Loren advises.
“The leaves continue to use sunlight to make energy for the roots and next year’s flowers. Leave them in place until they naturally turn yellow or die back.”
Any foliage that is dead, damaged or diseased can be removed straight away. Healthy leaves, however, should be left to die back naturally so the plant has as much time as possible to replenish its energy reserves.
3. Avoid overwatering
Irises generally prefer free-draining conditions and can suffer if their roots or rhizomes remain wet for long periods.
“Irises do not like sitting in wet soil,” says Loren. “Water them during long dry periods, but do not keep the soil constantly wet.”
Bearded irises are particularly vulnerable to rot, especially when planted in heavy soil or covered with a thick layer of mulch. Check that water can drain freely around the plant and avoid piling compost or mulch directly over exposed rhizomes.
4. Check whether the clump is overcrowded
Once flowering has finished, take a closer look at the size and condition of the clump.
“After flowering, check whether the plants have become overcrowded,” Loren says. “The clump may need to be divided if it is producing fewer flowers or if the rhizomes are growing too closely together.”
Other signs that an iris may need dividing include a congested mass of rhizomes, weak flowering or a bare area developing in the centre of the clump.
5. Divide bearded irises in summer
Bearded irises usually benefit from being divided every three to five years.
“The best time is in summer, around six weeks after flowering,” says Loren. “This gives the new plants enough time to grow roots before winter.”
To divide a clump, carefully lift it from the soil using a garden fork. Separate the rhizomes and inspect each section before replanting.
“Throw away any sections that are soft, rotten or badly damaged,” Loren advises. “Each healthy piece should have roots and a fan of leaves.”
Trimming the leaf fan can make the divisions easier to handle and reduce water loss while the plants re-establish.
6. Replant rhizomes at the correct depth
Planting depth is especially important for bearded irises.
“When replanting bearded irises, place the rhizomes close to the soil surface,” says Loren. “Avoid planting them too deeply, as this can reduce flowering and increase the risk of rot.”
Choose a sunny position with well-drained soil. The upper part of the rhizome should remain visible or sit only just beneath the surface, rather than being buried deeply.
7. Choose the right fertiliser
Feeding is not always necessary, particularly if the soil is already fertile, but the type of fertiliser matters.
“Avoid using a fertiliser that contains too much nitrogen,” Loren warns. “This can produce plenty of foliage but fewer flowers.”
Where feeding is needed, use a low-nitrogen fertiliser and apply it according to the manufacturer’s instructions. Avoid overfeeding, as vigorous leafy growth does not necessarily lead to more blooms.
The most important iris aftercare rule
“The most important tip is to remove the old flower stems while leaving the healthy foliage in place,” says Loren. “Those leaves are helping the iris store the energy it needs to flower again next year.”
In practice, that means deadheading promptly, watering only when conditions are dry and waiting until the leaves have yellowed before cutting them back. Combined with occasional division and well-drained soil, these simple steps will help keep irises healthy and productive for years to come.
Summer gardening edit
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