Bearded irises develop tall spikes of purple, red, yellow, white, or pink blooms, sword-like fans of tall green leaves.
The low-maintenance plants thrive in US hardiness zones 3 through 9. Cutting back irises regularly may increase flowering while keeping foliage healthy and attractive.
Irises bloom once per year and typically in late spring or early summer. They can also be late bloomers and produce a second raft of flowers during the late summer.
Following the opening of all the buds and the bloom period has ended, stalks should be cut back to the ground. (Learn When Do Irises Bloom)
Removing flower stalks prevents seed development and encourages repeat bloomers to go for the second flowering phase.
By stopping the seeds, you can make your plant healthier as it can devote energy and nutrients to root and foliage growth rather than seed production.
You can learn more about when to cut back iris leaves for the best future growth and health in our guide.
Should Iris Be Cut Back for Winter?
While iris plants are forgiving, there are some tips and tricks that determine when to cut back irises and how to do it.
Iris plants are the best cut back in the fall, although the spent flower stalks may be removed during the spring after plants end their blooming, yet leave foliage standing through the summer.
In mid-fall, use a pair of sharp garden scissors or pruning shears to snip through the broad leaves, and cut leaves back to 3-inches above the soil line and remove trimmed foliage, fall leaves, and pull back debris that may cover the rhizomes.
Iris plants typically cut back in the fall, yet leaves can be left to die back naturally, or you can cut them back when crisp, freezing weather is forecast. (Find the Best Weed Killer for Flower Beds)
Iris plants need little care throughout the summer after blooming in late spring. Just remove spent flower stalks after blooming to let the plant channel energy into leaves and roots.
How Do You Winterize Irises?
Iris plants are hardy perennials, and the rhizomes are planted on the soil surface with roots buried deep in your flower bed. When you prepare and condition your iris plants, they require little mulch or winter protection.
Decaying leaves and detritus need clearing away to prevent contamination.
Cut back the leaves and stems on your iris plants using a sharp knife or garden shears once some leaves turn yellow and droop. Leave green growth intact as your plants need this for survival. The best times for this are after the first frost in September or October.
Clear your iris bed of plant debris as well as leaves and decaying matter.
Mulch around your iris plant once the ground freezes and use just one inch of sterile straw or salt hay. Iris in warmer regions is better without mulch.
Once the weather warms, remove any straw or hay.
How Do I Get My Iris to Bloom Again?
The rhizome being close to the soil surface is the start of the ideal growing conditions. To bloom again, follow these tips.
Plan your iris garden when you know your iris species. If planting bearded iris, they like the right sun conditions with 6 to 8 hours direct sun daily. Soil should be well-draining loamy with a composition of sand, silt, and clay.
During the late summer thru early fall, and the local nighttime temperatures sit at 40 to 50 degrees Fahrenheit, which will offer the best times to plant and give you the best chances of flowering come the following spring and summer.
- Aerate your soil with a tiller to around 12-15 inches deep.
- Add a 2 – 4-inch-deep layer of compost.
- Make a mound for the rhizome by digging a shallow hole about 10-inches in diameter with a ridge in the center.
- Place the rhizome horizontally and carefully spread roots down the sides of the mound.
- Cover the roots and your rhizome bottom with soil.
If you plant Dutch iris, plant the bulbs, so the pointed side is upward around 6 inches beneath the soil line. Fall and spring are suitable for planting Dutch iris, and it is best when planted in a group of 10 in a square foot area. (Learn How to Keep Squirrels Out of Flower Pots)
Once you bury rhizomes or bulbs, water them immediately.
Deadhead the bearded iris frequently, as you will, encourage new blooms from buds growing further down the stem.
What Do You Do with Iris When Finished Flowering?
- After blooming is finished, cut flower stems down at their base. However, make sure not to trim iris leaves once the plants have finished blooming. It is the leaves that enable your plants to carry out photosynthesis for next year’s growth.
- Just make sure to cut off brown tips, and then you can also cut the flowering stalk down to the rhizome as this can help stop any rot setting in.
- Make sure when pruning, you remove any dead iris foliage around the stems or rhizomes of the plants on the ground, as this can lead to rot or disease. When cutting back your plants, take the time to check for iris borers, as this is the best time you can spot them.
- Irises will need to divide every three to five years to deliver the best growth. Trimming back your foliage to a third of the height. Once you do this, dig up the roots six weeks following the final flowering cycle. Cut your rhizomes into 3 to 6-inch pieces which contain both leaves and roots.
- Replant these 10 inches apart, so the tops of the rhizome sit just below the surface of the soil.
With all the above, you will see when to cut iris back is straightforward, and it is all part of the natural iris care procedure you’ll follow in your gardening.
So long as you clear any old leaf compost after they stop blooming in late fall, your plants can care for themselves. Iris takes little care to keep them healthy, and your garden will look the better for it.