Iris germanica: how to propagate them?

When to divide irises?

Division takes place after the flowering, when the plant is in a dormant state (yellowing foliage), between July and October. We suggest repeating the operation every four years.

Necessary materials for dividing your irises

• Spade or fork
• Pruning shear or sharp knife
• Gardening gloves

How to divide irises?

• Start by preparing the soil where you will plant your irises. Preferably choose a location where irises have not been planted before. Using a soil aerator or a spade, loosen the soil to a depth of 10 cm, incorporating coarse sand or gravel if your soil is heavy. Iris germanica require a very well-draining substrate!
• Uproot the clumps with a fork, being careful not to damage the rootstocks.
• Remove the excess soil around the roots.
• Next, cut segments with roots and leaves, taking them from the outside of the rootstock to obtain the youngest parts. Make clean cuts using a disinfected knife to prevent the development of diseases. Only keep healthy and undamaged fragments.
• Trim the leaves to reduce their surface area to one third of their original length.
• Plant the rootstock segments 30 centimetres apart, allowing the top of the rootstock to be level with the soil surface. Replace the soil and gently firm it down.
• Finally, remember to water lightly to ensure their establishment, for a beautiful flowering next year.

Tips and mistakes to avoid

Tips for a successful propagation

Always plant the rootstocks slightly exposed to avoid rotting

• Unlike other plants, iris needs its rootstock to remain partially exposed to the sun.
• If buried too deeply, it risks rotting due to moisture.
• A good technique is to leave the upper half of the rootstock above the soil.

Divide every 3 to 5 years for beautiful flowering

• Over time, the clump of iris becomes too dense, which reduces its flowering.
• By regularly dividing (every 3 to 5 years), you ensure good renewal and prevent the centre of the clump from deteriorating.
• A good indicator that it’s time to divide: fewer flowers and heavily overlapping rootstocks.

Label the varieties to keep track

• If propagating several varieties, it can be difficult to keep track before flowering.
• A simple tip is to label each variety with a tag (tag planted in the soil or coloured ribbon on the leaves).
• You can also note the colours and heights of the irises to organise your bed effectively.