General Information about Irises

shutterstock 563513698 FloraQueen EN General Information about Irises

While they may not have the level of popularity that flowers like lilies do, don’t sleep on irises. These flowers also have numerous varieties that are applicable in various contexts and to various needs. In fact, it could be said that you can find an iris for just about any garden.

The iris also has a neat origin story, as it gets its name from Greek culture. Whether it is summer or spring, you can count on an iris to bring a new layer of beauty.

Most irises are hybrids, such as the Bearded irises. There are several common varieties, and there are several things you need to learn. Prepare yourself as this article teaches:

The information is made as simple and as practical as is possible, so don’t worry about complexity.

Basic Iris Information

This section is just some general information that is useful for those who plan to handle irises.

First, there is the matter of height. Irises can grow to be many different heights based on the variety. The range of an iris’ final height can be anywhere from six inches to four feet.

Some irises, such as Iris macrosiphon, can tolerate partial shade. Most of them, however, must be exposed to full sunlight for at least half of the day. Though you can grow most of these in partial shade, they are likely to not flower.

Irises usually bloom in either spring or summer. There are some that bloom in one of the two seasons and some that bloom in both. There are also reblooming varieties that bloom in summer and fall.

Irises are toxic to pets, so bear that in mind with your placement in your home.

Iris Types

Though there are many varieties of irises, they all fall under two major groups. There are bulbous irises, and there are rhizomatous irises. The bulbous ones generally bloom in the spring, while rhizomatous ones tend to bloom in the summer.

Rhizomatous irises get their name because they are grown from rhizomes. A rhizome is a type of bulb. Rhizomatous irises have three subdivisions, which are as follows:

  • Crested – These irises thrive in humus-rich soil and either partial shade or full sun.
  • Beardless – These are very adaptable, which makes them excellent for low-maintenance applications.
  • Bearded – These get the name from the hairs that are in the center during fall. Most of them produce multiple flowers per stem.

Bulbous irises include Dwarf irises and Dutch irises. They are characterized by their shedding of leaves after blooming. This is followed by a dormant period. These flowers are good for forcing in pots.

How to Plant Irises

There are several areas that you need to consider as you plant your irises.

Late summer or early fall is best for iris planting. This allows them to properly establish roots prior to growing season.

Any sunny location that doesn’t feature standing water is good for irises. Raised beds are recommended for drainage purposes.

Beds must be prepared up to two weeks prior to planting. Allow for a depth of 10-12 inches of depth for drainage. Rhizomes are to be slightly visible when planted, while bulbous irises should be planted five feet deep.

For rhizomes, create two rows in your soil and leave a small ridge between. The rhizomes are to be placed on the ridge, and their roots are to be spread to either side.

Ensure you space bulbous irises at six bulbs per square foot. Note that it is best to plant them end up and roots down.

Caring for Irises

As is the case with planting, there are several care tips that you must remember when dealing with irises.

Rhizomes must be divided every three to five years. The best time to do so is soon after blooming has taken place.

Irises don’t require much water once they get going. Feel free to apply extra near bloom time if the soil seems unusually dry.

Low-nitrogen fertilizer is best, and it should be applied a month before bloom time. Do not place mulch on top of rhizomes as that is a recipe for rot.

Ensure that you cut back flowering stalks after flowering has taken place. However, leave the foliage intact, so that energy and nutrients can be stored. When ground-level leaves turn yellow in fall, be sure to trim them.

Irises can be destroyed by thrips and iris borers. Aphids, snails, slugs, and nematodes can also be a problem.

Design Tips That Involve Irises

The final thing to look at is some design tips that you can use in your iris placements.

Irises should be planted somewhere where you can watch the beautiful creatures they attract. These include hummingbirds and butterflies.

Iris are excellent cut flowers. Note that temperature has a great bearing on vase longevity. The maximum vase life is about a week.

Trimming multi-flowered irises from the top down can keep them looking radiant. This should be done as the flowers open and fade.

While you should keep irises from being crowded, they look excellent next to peonies and ornamental sages.

Iris blossoms are fantastic additions to perennial borders. Taller varieties should be planted in the back of perennial borders or with shrubs. Mid and low-growing varieties are best placed mid-border.

Japanese and Siberian irises make great poolside flowers. This is because they can remain radiant for the entire duration of summer.


Irises are wonderful multi-purpose plants that come in many varieties. A lot of useful information was discussed above.

Irises usually bloom in spring or summer and can be various heights. Some can tolerate partial shade, and all are toxic to pets.

Rhizomatous and bulbous are the two types of irises. The former can be broken down into crested, beardless, and bearded.

Try to plant your irises in late summer or early fall in a sunny location with no standing water.

While irises are low maintenance when they get going, there are still things to attend to. They must be divided, stalks must be cut back, and you need to battle pests and diseases.

There are multiple aesthetic touches that can be achieved with irises. For example, they are great for perennial borders.

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