Help us achieve our goals:
make a donation »
Join the RHS today and
support our charity
Free personalised gardening advice
RHS members get reduced ticket prices
RHS members get free access to RHS Gardens
Reduced prices on RHS Garden courses and workshops
020 3176 5800
Mon – Fri | 9am – 5pm
Make a donation
Join the RHS today and support our charity
Register for free to receive our newsletters, add comments to blogs/articles and to save content.
Irises can be kept healthy and full of flowers by dividing clumps before they get congested. This is also a good way to increase stocks of plants.
Suitable for Bearded irises with rhizomes (fleshy stems at soil level), plus clump forming herbaceous irisesTiming Mid-late summer for rhizomatous irises; autumn or spring for clump-forming irisesDifficulty Moderate
Both clump forming irises and those with rhizomes (fleshy stems at soil level) can be divided. Irises that are grown from bulbs are not suitable for division.
Bearded irises (sometimes sold as Iris germanica cultivars) have large fleshy stems (rhizomes) at soil level and flowers with soft hairs (the ‘beard’) on their lower petals (falls).
Siberian irises are clump-forming irises with beardless flowers. Large clumps can be divided to rejuvenate them if flowering has become reduced at the centre of the clump.
Iris unguicularis are low-growing clump-forming irises with beardless flowers that flower in late winter and early spring. Large clumps can be divided to rejuvenate them if flowering has become reduced at the centre of the clump.
Pacific coast irises are low-growing clump forming irises with beardless flowers and grass-like leaves. Large clumps can be divided to rejuvenate them if flowering has become reduced at the centre of the clump.
Irises for dry soils (bearded iris)Irises for moist soils (beardless iris)Perennials: dividingRHS video: Dividing irises
the RHS today and get 12 months for the price of 9
RHS members can get exclusive individual advice from the RHS Gardening Advice team.
Register for the site or sign in to share your experiences on this topic and seek advice from our community of gardeners.
We're a UK charity established to share the best in gardening. We want to enrich everyone's life through plants, and make the UK a greener and more beautiful place.
Like this page on facebook
Click on the Tweet button below to compose your tweet.
Join the RHS today and get 12 months for the price of 9