Answer: Irises are fairly hardy plants. Since they have finished blooming you can prune the tops down by about two thirds and dig them with a garden fork (to help prevent damage to the rhizomes). It would be best to plant them in containers but failing that you can set them in soil in a cardboard box - just enough soil to cover the rhizomes and roots - and keep them in a shady spot in the garden. Water the soil so it doesn't dry out completely. This will keep the rhizomes plump. You can replant them after your deck is built.
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