Can Iris Survive A Freeze?

Credits to: @thrujosephseye

If you live in a cold climate, you’ll be pleased to learn that iris bulbs can withstand freezing temperatures and even frost, making them a popular perennial flower. In zones 3 through 9, iris (Iris spp.) can endure more than 200 different environmental conditions. Some iris varieties are bulb-based, while others are rhizome-based, with thick, fleshy stems emerging from the ground. In the winter, the amount of care an iris plant needs will depend on the climate, the plant’s age, and the species.

However, a sudden cold snap will kill the flowers. There will be plenty of flowers to enjoy for the next two weeks in March and November because this Iris blooms over two weeks. A temperature of 0°F (-17.8°C) was recorded.

Easy Winter Care Tips

During the winter, the winter iris (Iris unguicularis) is a beautiful plant that blooms in areas with mild winters. It’s sometimes called the Algerian Iris as a flower that grows in the Mediterranean because it comes from there. The smell of this pretty plant, which blooms in the winter, will quickly fill your home with a sweet vanilla-lemon scent.

This plant has soft blue flowers with a yellow center and purple veins. It grows in clumps and has grassy, deep green leaves. In the long run, the clumps get bigger, and older winter irises can produce more than 100 blooms. When you plant plants in the spring, they grow up to 18 inches tall and produce flowers from November to March when they’re ready. For the best growth, they need a lot of sun all year and soil that isn’t too wet. Do well when they are planted against a fence or inside a home where they are less likely to get cold, wind, or frost.

So many varieties of color and flower forms are available that growing irises can be a real treat. Even though irises require little care while blooming most of the year, those who live in colder climates will want to consider winter protection for their plants.

Getting Ready for the Coming Cold Weather

Even though irises are low-maintenance plants, protecting a newly planted iris from frost requires some foresight. When it comes to the roots of your irises, no matter what variety you choose, you need to make sure they are strong enough to withstand the cold weather. Keep this in mind when separating an overcrowded iris plant, which Utah State University Extension recommends doing two to five years after planting.

According to the American Iris Society, irises should be planted four to six weeks before the first hard freeze of the season to give them time to develop strong roots. If you live in an area where the winters are cold, you may have to plant your Iris at the middle or end of summer. Irises can thrive in these areas if you plant them early in the spring, so keep that in mind. It is possible to put off planting until the fall in areas with mild winters.

How to Prevent Leaf Spot

During the final stages of the growing season, it is beneficial to inspect the iris bed for disease, dying plants, or plants that need to be divided. Trim flower stalks to the ground as soon as they have finished blooming. One less thing for the plant to worry about as it stores energy for winter. Once the foliage has turned yellow or brown, it’s imperative to remove it or cut it back. Wait until it turns yellow or brown before cutting it back to 6 inches in the fall.

It may not be enough to protect a newly planted iris from frost in the long run. Iris have a lot of diseases that they are vulnerable to. Leaf spot, a fungal infection that causes tan lesions on the leaves of plants, can spread during the colder months. You’ll want to take steps to stop the spread of leaf spots. Leaf rot is most common in irises that grow from bulbs, but species that grow from rhizomes can also be affected.

Spots on the leaves of an iris plant are ugly, and over time, they can weaken the plant and make it useless. The fungus that causes leaf rot can live on the leaves of old plants through the winter. You can think of this as how the fungus moves from one plant to another. As soon as fall comes around, remove all the dead leaves from your iris plants. You can either bag them and throw them away or burn them.


When starting a new iris in a cold climate, mulch is essential. Hay or evergreen boughs are two suggestions from the Missouri Botanical Garden for this project. Iris plants that grow from rhizomes should be mulched in areas where the ground freezes and thaws repeatedly. Frost and thaw could cause the roots of an organism to be exhumed from the ground. Bearded irises, whose rhizomes are typically planted just below the soil’s surface, present a particular risk.

As the American Iris Society suggests, you can use salt hay to prevent frost damage. After the first hard frost of the season, mulch in the late fall. It is best to remove mulch in early spring once the ice and snow have melted. The University of Nebraska-Lincoln Extension recommends gradually avoiding harming the plant. Iris plantings that are not mulched should have their rhizomes pushed back into the soil.

A winter annual, the African Iris thrives in colder regions. Overwintering containers in a bright window with minimal watering during the winter is a good option. Alternately, you can put African Iris in pots and keep them in a protected area that is cool and dark throughout the winter. Remove dead leaves in the spring (or fall), fertilize, and water, then watch for new growth to appear in the garden.

During the winter months, mulching is necessary. The needs of iris plantings are very similar to those of other perennials, so winter mulch can be used on them in climates where it is beneficial. Rather than keeping plants warm, a winter mulch’s primary goal is to slow down or prevent the extreme temperature swings caused by freezing and thawing, which can force plants to the surface and leave them vulnerable to winter rot. In the winter, snow is an excellent insulator because of its density.


Water is an important component of winter maintenance. Watering in the winter is not desirable, and in many cases impossible, in areas where the ground freezes, so winter provides a break from this particular garden chore. Many gardening books assume that this is the case in all locations. To prevent your garden from becoming completely dried out, keep an eye on it during periods of warm weather if you live somewhere that experiences both dry summers and warm winters. Remember that the plants are dormant or semi-dormant and that evaporation is reduced due to the cooler temperatures.