Things You'll Need:
- Scissors or knife
- 10-10-10 fertilizer
- Manure or compost
- Spade
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Step 1
Divide Siberian irises in late summer or early fall every three to five years. This will ensure time for the Siberian irises to get re-established before winter.
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Step 2
Cut off any remaining seed pods on the Siberian irises and cut the foliage back to about 3 inches above the ground. This will make the rhizomes easier to work with.
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Step 3
Dig up the Siberian irises' rhizomes and roots. Remove them all from the ground without harming them. Dig in a circle about 8 to 10 inches away from the base of the plant to accomplish this.
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Step 4
Remove any dead or old roots from the Siberian irises. Dead roots will look woody, while younger roots will be supple. Divide the roots into two or three separate clumps with top growth attached to each of them.
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Step 5
Replant the Siberian irises at a width of 12 to 24 inches. Dig a hole 3 to 4 inches deep and place the rhizomes in the hole at an angle so the roots are facing down and the rhizomes are exposed by about a half an inch. Cover the hole with soil and pat down firmly.
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Step 6
Water the divided Siberian irises well for about a month after you divide them. Water every two or three days for about 5 to 8 minutes per watering. You may add a water soluble 10-10-10 fertilizer the first time you water the Siberian irises after you replant them.
