You can save iris bulbs for next year by digging up the rhizomes after blooming ends and storing them in a cool dry spot. Irises grow from rhizomes rather than true bulbs. That small difference changes how you handle the storage process. Your rhizomes need drier conditions and more airflow than most tender bulbs do.
When I first divided a crowded iris bed in late summer, I wasn't sure they'd survive storage. I trimmed the leaf fans, cured the cuts for two days on newspaper, and packed them in paper bags with dry peat moss. Come spring, every one of those rhizomes sprouted strong shoots within two weeks of planting. That sold me on iris bulb storage as a solid way to save and share your irises.
Storing iris rhizomes calls for a drier approach than you'd use with dahlias or gladiolus. Your rhizomes sit close to the soil surface in the garden and prefer good drainage at all times. Too much moisture in storage causes bacterial soft rot, which turns firm rhizomes into smelly mush fast. Keep your packing medium on the dry side and check monthly for any signs of dampness or decay around the stored roots.
Trim each leaf fan to about four inches before you store your rhizomes. This cuts down on moisture loss through the leaves and makes the rhizomes much easier to pack. Use clean scissors and make a straight cut across the top of the fan. The trimmed leaves will dry out during storage, and that's fine. New growth will push out from the rhizome itself once you plant it in the spring soil.
Dig and Clean After Blooming
- Timing matters: Dig irises after the blooming period ends in summer so the rhizome has stored up enough energy for winter.
- Shake off soil: Remove loose dirt by hand and brush off any clumps that stick to the roots and rhizome surface.
- Check for damage: Look for soft spots, insect holes, or signs of rot and discard any rhizome that shows these problems.
Cure Cut Surfaces Before Packing
- Dry for two to three days: Set divided rhizomes on newspaper in a shaded spot with airflow so cuts can form a callus layer.
- Dust with sulfur: Sprinkle garden sulfur powder on all fresh cuts to block bacterial soft rot from taking hold during storage.
- Heal before storage: UW-Madison Extension supports letting division wounds seal before packing to reduce infection risk.
Pack and Store in Cool Dry Spot
- Use mesh or paper bags: These allow air to move around the rhizomes and prevent moisture from building up inside the container.
- Add dry peat moss: A thin layer of peat keeps rhizomes from touching each other and absorbs any extra moisture in the bag.
- Keep temps steady: Store at 40°F to 50°F (4.4°C to 10°C) in a dark spot like an unheated garage or basement shelf.
Overwintering iris plants in storage works best when you check on them once a month. Feel each rhizome for firmness and look for mold or soft patches. Pull out anything that has gone bad so it doesn't spread to your healthy rhizomes nearby. Your quick monthly check takes just a few minutes and keeps the whole batch safe through the cold months.
In my experience, iris rhizomes are some of the easiest garden plants to store over winter. They don't need much fuss, and their firm woody texture holds up well in dry conditions. Plant yours in spring with the top of the rhizome just barely below the soil surface. You should see new leaf fans pushing up within a couple of weeks. Your blooms will follow the next season as the plants settle into their new home.
Read the full article: Storing Bulbs: Full Guide for Better Blooms
