Answer: The flowering stems of fortnight lily are perennial, so don't cut them back after flowering as you might for most other iris like plants. You can't do anything about the height of these plants, but you can dig and divide the clumps if the bed is over-crowded. Divide the rhizomatous clumps after the plants have flowered. The new divisions may take several weeks to get established, so be patient and pamper them for a while. They will grow new flower stems as soon as they're established in their new homes.
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