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Welcome to our Head Gardener’s Journal

In this monthly column, we will share technical aspects of our work and also keep you up to date about ongoing projects. If there is any topic you might want to hear more about, please ask during your next visit!

Splitting Iris Germanica

German irises need to be split every three to five years to stop them encroaching on other plants.

Overgrown Iris ‘Annabel Jane’

The irises are split after they finish flowering between June and August. Unlike other plants, they can withstand division and transplantation in dry conditions. However, they need to be given enough time to put down roots before the winter.

Iris ready for splitting

Individual rhizomes can be removed from the main plant to reduce the size of the clump.

Reducing the size of the clump by removing individual rhizomes

Alternatively, the whole clump can be dug up and the rhizomes divided using two forks. This however risks losing a flowering season as replanted rhizomes rarely flower in their first year. The first method will by contrast enable the remaining rhizomes to keep flowering. Once the rhizomes have been isolated, their leaves are trimmed off to minimise strain on the plant, and they are re-planted. 

In England’s mild and humid climate, it is advisable to plant rhizomes on the surface of the soil to prevent rotting. Pinning them down with tent pegs anchors them in place until their roots have grown.

Trimming and replanting of rhizomes​​​
Trimming and replanting of rhizomes​​​
Trimming and replanting of rhizomes​​​​