Flowering is nearly over. What to do next with the irises which are in place and now waning and how to prepare the ground for those irises which are to be divided or for the new acquisitions?
Irises which are already in place
Once the last flower has withered, you must cut the stem at rhizome level or 10 cm above it, but leave the leaves until September (unless they are particularly blemished).
You can also lightly work-in some low nitrogen /high potash and phosphate organic fertilizer around the clusters: this will favour the growth of rhizomes which are to flower the following spring; it will also air the soil which proves extremely beneficial.
Preparation of a new flower bed
If the place you have selected for plantation is overgrown with hardy weeds, you will need to get rid of these ; otherwise the new flowerbed will soon be overtaken by these tenacious invaders.
If there are no hardy weeds, dig the soil down 20cm and mix-in perfectly decomposed compost at least 3 weeks prior to planting. In clay soils, you can also add 100 to 200 grams of lime per square metre in order to improve the soil structure and to slightly raise the ground of the flowerbed.
Finally, whether it be an existing iris bed or a new plantation, watering twice a month during the summer season will favour growth.