How to plant, grow and care Iris plants (Detailed Guide)

Want to grow Iris Plants in your garden? Check out a detailed guide on how to plant, grow, and care Iris Plants.

Iris is a genus of 260 to 300 species of plants with showy flowers. Her name comes from the Greek word for rainbow, which is also the name of the Greek goddess of the rainbow, Iris. Some authors claim that the name refers to the wide variety of flower colors found among the many species.

In addition to being the scientific name, iris plants are also widely used as a common name for all species of iris, as well as for some belonging to other closely related genera. A common name for some species is ‘flags’, while plants of the subgenus Scorpiris are widely known as ‘junos’, particularly in horticulture. It is a popular garden flower.


The iris most commonly planted in the United States is the bearded iris. The height of the bearded iris plant varies from 7 cm for the lowest of the dwarf iris flowers to 4 feet for the highest of the bearded Iris.

The iris plants in the middle group reach 1 to 2 feet in height. Iris flowers bloom in shades of purple, blue, white, and yellow and include many hybrid versions that are multicolored. Louisiana’s ‘Black Gamecock’ iris from the Louisiana series is a deep purple color that almost looks black.

Iris plants
Iris plants

The flowers of the Siberian iris are more delicate, but they are also available in a multitude of colors. The variety of Butter and Sugar’ has a delicate yellow and white color.

The Spuria iris, planted next to the Siberian iris, offers flowers in late spring when the bearded iris blooms. Many of the flowers are furrowed and include a draped set of three external sepals called drooping.

How to plant, grow Iris plant

Let us check out how to plant and grow Iris plants.

How to grow Iris Plant

  • Iris plant not need any additional attention to grow up.
  • Irises will bloom outstanding in full sun.
  • They can tolerate only half a day of sunshine, but it is not ideal.
  • Without enough light, they will not bloom.
  • Bearded Iris should not be shaded by other plants; many do better alone in a special bed. 
  • They prefer fertile, neutral to slightly acidic soils.
  • Good drainage throughout the year is very important.
  • They do not tolerate damp soil in winter.
  • Loosen the soil with a cultivator or garden fork to a depth of 30 to 40 centimeters and mix in a 5 to 10 cm layer of compost.

How to Plant Iris Plant

  • For bare root Irises, plant the rhizome horizontally with the upper part exposed. In hot summer climates, plant the rhizome just below the surface of the soil.
  • Plant the rhizomes individually or in groups of three, separated by one every 30 centimeters, depending on the size.
  • Dig a shallow hole 25 centimeters in diameter and 10 centimeters deep. Make a crest of soil in the middle and place the rhizome on the crest, spreading the roots on both sides. Fill the hole with soil and gently firm it, exposing some of the rhizome and foliage.
  • It is easy to make the mistake of planting Iris too deeply. The rhizomes of these plants must be partially exposed to the elements or finely covered with soil in hot climates. If they are buried too deep, they will not perform well.
  • Do not cover the rhizome, as this practice can promote rot.
  • Water the Iris plant thoroughly

How to Care Iris plant

  • Fertilize in early spring with a universal fertilizer applied to plants. Avoid the superficial application of fertilizers with high nitrogen content or careless coverage with organic matter, which can cause the rhizome to rot. Re-bloom work best if fertilized again after the first flowering wave ended.
  • Do not over water the irises; too much moisture in the soil can cause the rhizomes (roots) to rot. Water steadily and deeply, especially during the summer drought.
  • Keep rhizomes exposed. Unlike bulbs, which thrive underground, the rhizomes of the iris need a little sun and air to dry them. If they are covered in dirt or filled with other plants, they will rot. Iris can benefit from surface coverage in the spring.
  • Observe the iris borers in the foliage (dark vertical lines that may appear watery appear on the leaves).
  • Deadhead (removing worn flowers) constantly; Bearded irises bloom sequentially on buds spaced along the stems. 
  • After flowering is complete, cut the flower stems at their base.
  • But do not trim the leaves of the iris after they have finished blooming. The leaves photosynthesize for next year’s growth.
  • Cut the brown tips and cut the stem of the flower to the rhizome to prevent rot.
  • After a heavy frost in the fall, cut the stiff foliage, remove any leaves that appear stained or yellow and throw all the debris in the trash.
  • If the foliage of the iris is affected by heavy frost, remove and destroy it to remove the eggs from the borer.
  • For winter protection, cover the rhizomes with 2.5 to 5 centimeters of sand covered with a light layer of perennial branches, applied after the soil freezes and removed when the Forsythias bloom the following spring.
  • In early spring, remove winter mulch and any old foliage to allow fresh new growth and prevent iris borers.

Where do Irises Plants grow best?

Where do Irises grow best
How to plant, grow Iris plant

Plant Iris in late summer until early fall, when nighttime temperatures are between 40 and 50 degrees Fahrenheit or higher. This gives them plenty of time to calm down before the next winter. Tall bearded lily varieties are best planted around autumn because they go dormant in early summer.

If you put rhizomes or Iris in a container at the beginning of the year, plant them as soon as is convenient. It is better to put them on the floor than to wait until the ideal time. Choose a spot in the garden that receives a good 6 hours of sunshine a day and has good drainage. The iris can withstand drought, but not soaked feet.

Iris do well in most regions of North America and are resistant in zones 5 to 9; they bloom best in full sun, but can also be planted in partial shade.

Many gardeners treat Dutch Iris as annuals, planting fresh bulbs every season, but you can encourage them to become natural by planting in a sunny location where the soil warms and dries in the summer.

Should I deadhead Irises?

After your irises have bloomed, you can cut the stem of the flower; this process is known as “deadheading”. You can use a clean knife or utility scissors for this process if they are too thick to break by hand. However, you shouldn’t cut or tie the lily leaves at this point, even if they get a little ugly.

After an iris blooms (the same goes for tulips, daffodils and other bulbs or bulbs), it needs to store energy for next year’s flowers. It does this through photosynthesis and, for that, it needs its leaves. Eventually, the iris will end its energy restoration process and the leaves will turn brown.

At this point, you can also cut the leaves if you want. This is not necessary, but it is only for cosmetic purposes. Some Iris is indeed the type that blooms again, but these are some of the more recent varieties.

Do Irises need Sunlight

Iris needs at least half a day of sunshine. In extremely hot climates, a little shade is beneficial, but in most climates, the iris works best with at least 6 hours a day of full sun. For irises to bloom consistently, they need full sun, good drainage, plenty of space and quality soil.

To improve your chances of flowering, add fertilizer, and divide the large groups. Only 60-75% of iris flowers in the first year after planting. Sometimes they need another year to settle. Unusual weather conditions or frost in late spring can also damage iris flowers.

For longer-lasting flowers, cut your iris early in the day with the newly opened buds. Place them in a bucket of warm water and cut the tip of the stem under water again at an angle of 2.5 cm upwards. Display your iris in a cool niche, away from direct sunlight and drafts. Squeeze and remove faded flowers immediately.

Are Coffee Grounds good for Irises?

The iris is an acidic loving plant, so love being in an acidic environment provided by coffee grounds. So don’t hesitate to apply coffee powder to your beautiful iris plant to make it look brighter. Since coffee beans are organic material, they release their nutrient content slowly as they degrade in the soil.

This allows you to use coffee grounds as a slow-release fertilizer for your iris plant when mixed with the normal potting mix you are using for your iris plants.

Coffee powder contains a lot of nitrogen compared to phosphorus and potassium. It is possible that iris plants with relatively higher phosphorus and potassium requirements will not work as well as they should if you only use coffee powder to fertilize your plants.

While there may be several problems with doing this, it can provide a sustained source of nutrients for up to 6 months, so excessive availability can affect the growth of your iris plant.

How many times a year do Irises bloom

How many times a year do Irises bloom
How many times a year do Irises bloom

Iris bloom once a year, but if you bloomed again, you can get up to two flowers a year. It is not possible to spread the iris flowers for up to 4 weeks or more. To enjoy its huge and exotic flowers for longer, you will need to select varieties with early, intermediate and late flowering times.

  • Early season: Bearded Iris usually open their showy flowers in early May and possibly in late April
  • Early Midseason: Iris bearded adorn the garden from early May to mid-May
  • Mid-season: parade of tall bearded Iris with fanfare in mid-May
  • Late Mid-season: Tall Bearded Iris participate in the garden show from mid-May to late May
  • Late Season: Bearded Iris star at the end of the iris show with their flowers opening to reveal their splendor in late May and early June

However, keep in mind that flowering times are approximate and highly dependent on climatic conditions. For example, a bearded iris that blooms early may bloom in late March in California, but not before early May in New York.

How fast do Irises spread?

Iris spread quickly and when plants overlap, they produce less of their beautiful flowers. Iris are perennials and will spread gradually from the roots over many growing seasons.

Every three to five years, you must divide the Iris into full flower beds and replant them to avoid competition for water and soil. Iris are easily propagated by the development of new rhizomes that ripen quickly. Because they spread so fast, Iris plants are easy to share. Every few years, Iris must be divided into daylilies to rejuvenate the plant.

Will Irises grow under trees?

There are some species of iris plants that can grow in the shade of trees or on the north side of the house. The Siberian iris is easier to grow in the shade of a tree. They thrive in full sun and partial shade. Although they grow in full shade, the lack of sunlight affects their growth and flowering.

These natives from Europe and Central Asia prefer USDA zones 3 to 8 and, unlike the bearded iris, will grow in medium humidity and humidity conditions, including heavy clayey soils. Native to North America, the iris with the southern blue flag also tolerate areas of light shade.

The majority of the iris will tolerate some shade, especially in warmer climates, stinking iris (Iris foetidissima) is the most tolerant shade of iris species. Although it also thrives in the sun and partial shade, the smelly iris, also known as Gladwin or coral iris, adds color to shady wooded gardens.

Should Iris leaves be cut back after blooming?

 Cut back the Iris leaves back six to eight weeks after Iris blossoms die back. Although the foliage looks ugly, it is slowly accumulating energy to store for the next flowering season. Rhizomes, or underground stems, store photosynthesized energy from the dying foliage.

If rhizomes do not store enough energy, their irises will bloom less vigorously or will not bloom at all next season. The only change you can make to the foliage is simply to fold the leaves down if they shake violently in all directions; do not tie them in a bundle, as this process makes photosynthesis difficult.

Its vegetation is ready to be cut when it looks yellow and has a paper texture. However, each leaf does not yellow in the same proportion as the others, it only cuts the portions that are obviously devoid of green pigment, called chlorophyll.

Your Iris plants can be pruned slowly from their yellowish foliage to create a more organized garden look. In the meantime, plant a distracting ground cover or other flowers blooming around your irises to disguise the location. The underbrush and spectacular flowers make it easy to ignore the dead leaves of the iris until you can fully trim the vegetation.

What can I plant next to Iris?

When the iris flowers fade, you will need a plants that will quickly fill your space. Therefore, following flowers are listed:

For a Spring Garden full of bloom, try these plants: 

  • Columbine
  • Daffodil
  • Allium
  • Tulips
  • Pansy
  • Peony
  • Lupine
  • Phlox
  • Violet

Shrubs that bloom in spring are old-fashioned favorite iris companion plants. Try the following:

  • Flowering almond
  • Lilacs
  • Forsythia
  • Weigela
  • Snowball bush

Some other plants that will quickly fill in as blooms fade are:

  • Coral bells
  • Poppy
  • Salvia
  • Daylilies
  • Black eyed susan
  • Cranesbill
  • Daisy
  • Monkshood
  • Delphiniums
  • Yarrow
  • Foxglove
  • Hyssop
  • Sedums
  • Chamomile

Is Epsom salt good for Iris?

Yes, there seem to be good relevant reasons for using Epsom salts for iris plants. Epsom salt helps to improve flower blooms and enhances the green color of the plant. It can even help iris plants to grow more. Epsom salt is composed of hydrated magnesium sulfate (magnesium and sulfur), which is important for healthy plant growth.

How do you propagate Iris Plants

Even if you don’t believe in its effectiveness, it never hurts to try. Magnesium allows iris plants to better absorb valuable nutrients such as nitrogen and phosphorus. It also helps in the creation of chlorophyll, which is vital for photosynthesis.

In addition, magnesium has greatly improved the ability of one plant iris of producing flowers and fruits. If the soil is without magnesium, adding Epsom salt will help; And since it presents little danger of overuse like most commercial fertilizers, you can safely use it on almost all iris plants.

How often should you water Irises?

Newly planted rhizomes need moisture to develop their root systems. Once established, the Iris should be watered when the first three centimeters of the soil have dried. The frequency of irrigation will depend a lot on your environment.

Watering too many Iris is a common mistake. After planting, water well and continue watering until the first good rains. If the lack of rain persists, irrigation must be deep enough to penetrate the shallow root system.

Less frequent deep watering is better than frequent shallow watering. Iris from Louisiana, Siberia, and Japan need more water than bearded ones.

Why are the leaves on my Iris turning yellow

The root rot is the iris of the disease, where you first see a yellowish color in the center of the sheet range. Over time, the center turns brown and collapses. The root of the iris is also known as soft rot, and if your iris has had it, you know why.

The leaves are pasty and the rhizome root is pasty. The root rot of the iris is caused by Erwinia carotovora, a bacterial phyto pathogen. It usually enters the rhizome through an opening created by some type of injury.

Any pest can provide this input, including borers, slugs, snails, beetle larvae or even the rude use of tools. Root rot in the iris always produces a soft, smelly rhizome. Often, you will also see rot on the leaves of the plant.

Rot of the iris root is not easy to cure. However, you can often avoid this by using good cultural practices in your garden. Make sure your irises are planted in sunny locations first. Good soil drainage is critical, so consider raising your beds, if necessary, to ensure adequate drainage.

Proper spacing between rhizomes is also important, as overcrowded plants are more vulnerable to bacterial growth.

Do not plant your rhizomes too deep in the soil and keep dirt at the base of the fans. Never use fresh compost on your iris plants, especially if drainage is an issue. Instead, feed your plants with mild fertilizers.

Why are my Irises not blooming

These are the following reasons that affect iris flowering. Try to overcome these problems so that your Iris plant will smile again in flower form.

1# Not enough Sunlight

Although an iris grows in the shade, it will produce few or no flowers there. It takes a lot of sun to bloom, according to the Missouri Botanical Garden. Plant your iris in the sunniest part of your garden and make sure that the tree branches do not shade the plant and that the surrounding vegetation is too far away to create shadows on the iris. However, some species of iris do well in half a sunny day.     

2# Lack of water

The iris is considered to be drought tolerant. However, when under stress due to lack of water, the first element sacrificed is flowering. Even the most prolific iris will not bloom unless it receives adequate moisture.

A general rule of thumb is to water an iris plants slowly when the top 5 centimeters of its soil are dry. Excess moisture is just as devastating as lack of moisture, but it causes rot and, especially in the bearded iris, leaf disease.

3# Planted very deeply

If you bury an iris rhizome too deep, it will reward you for not blooming or, worse, for rotting. The key to success when planting the rhizome is to allow the upper part to be exposed. This arrangement allows air to circulate around the rhizome and sunlight will ensure that it is not too humid. These are the perfect conditions for flowering to occur.

4# Too much nitrogen

Irises, like many flowering plants, do not bloom when there is too much nitrogen in the soil. Since the plant requires sufficient phosphorus, fertilizing it is a delicate balancing act. A soil test can help you determine what nutrients are missing from the soil and the best way to achieve a nutrient balance.

5# Too little space

If your iris has suddenly stopped blooming after years of growing in the same place, then it may be crowded. Solve this situation by digging up the rhizome or bulb and dividing it.

Splitting is easier if you trim the foliage of the iris to about 15 centimeters in height, shake the soil from the bunch and gently use your fingers to separate the young bulbs or rhizomes from the main tuber. Replant the resulting new Iris immediately and keep the soil moist as they settle.

Can I transplant Irises in the spring?

Do not transplant the Iris plant in the spring because you need to cut the foliage when transplanting the rhizomes, spring is a bad time to transplant the iris. Iris bloom in spring, between April and June, depending on the cultivar, and their foliage does not begin to die until July.

As they use their leaves to gather energy for next year’s growth, it is bad for the plant to remove the leaves before they have done their work. Instead, wait for the summer months.

Be sure to wait for the right time for the transplant. Although July is generally safe, if you’re not sure, wait until August.

Do not plant Iris in the shade, as they will not bloom very well and may have trouble gathering the energy needed for next year’s growth. If the planting site tends to get wet or swampy, incorporate organic matter to clarify and improve drainage, or rhizomes of the iris may have soft bacterial rot.

Can I transplant Irises in the spring

What causes brown tips on Iris leaves

The tips of the brown leaves of the iris are a sign that a plant is healthy iris, reallocating resources to its lower bases and rhizomes. In addition, the iris is developing new anchor roots that will take on nutrient and water support for new fans.

Once fully developed to start the process, the darkening and discoloration of the leaves should soften a little. This occurs naturally at this time of year. If the brown tips begin to progress through the blade or acquire a decided reddish hue with a yellow border, then other issues are at stake. But simply browning the ends is not a cause for concern.

Leaf spots are a fungal disease that causes brown to yellow spots on the foliage. These spots will start to increase and the centers will develop a tan tone. These spots are usually found near the tip of the leaf, but the stems, bulbs and flower buds can also develop the infection.

Fungal spores may start to grow on the spots, but they may not be visible without a magnifying glass. Leaf spots occur in humid conditions when the temperature is between 50 and 70 degrees. Fungal spores are transported through the air and can spread to other plants in the wind.

How do you propagate Iris Plants

The shoots can be swollen with time, which tends to inhibit flowering. This can be remedied by raising and dividing the rhizomes to give them a little more space. Wait until the cultivation is finished before propagating the bunch of irises, discarding the old woody rhizomes, and replanting only young, healthy plants in freshly prepared soil.

Follow these steps to easily propagate the iris plant:

  • Use a fork to dig up a bunch of engorged Iris. Remove the plants from the soil, taking care not to pierce the rhizomes.
  • Separate the congested rhizomes manually or cut them with a knife. Choose healthy pieces with leaves and discard old woody sections.
  • Newly planted rhizomes are vulnerable to wind rocks, so it’s a good idea to cut the leaves in half. Use a sharp knife to cut them.
  • Replant healthy rhizomes about 12 cm apart, with the leaves facing the sun. Make a shallow hole and half-bury the rhizome, pushing it firmly to lie down; they like to bake in the sun, so don’t bury them too deep.

Are Iris poisonous to dogs

Yes. Iris is poisonous to dogs. The highest concentration of toxin in the iris is believed to be found in the bulb, however, roots and leaves are also toxic if ingested. The toxic plant compounds of the iris are purgative resinous irisin and cytotoxic terpenoids.

The exact function of the toxin in the iris flower is still unknown, but scientists believe it contains ribosome-inactivating proteins (RIPs) that interfere with RNA and protein synthesis.

If your dog chews the iris or ingests a part of it, you can become very ill and have to be taken to the vet immediately. Depending on the amount and part of the iris consumed, symptoms can develop quickly or over a period of several hours. If veterinary care is not sought out, the consequences can be dire.

Can you grow Iris from cuttings?

Can you grow Iris from cuttings
Can you grow Iris from cuttings

No. Iris did not grow successfully through cutting. But if you use the tissue culture technique, you can get positive results. The subject of culture was included in the asexual propagation of plants, but most gardeners do not practice this method, which involves an extremely technical laboratory method.

In tissue culture, scientists take identical tissues, for example, those found in the growing tips, root tips, and plant embryos, and grow them in a specially prepared medium so that the resulting cell mass produces tiny new plants.

In fact, all of these new plants are clones. In other words, they are genetically identical to the plants whose parts have been used in tissue culture.

When to plant Iris bulbs

Planting times for iris bulbs vary according to climate and variety, but typically, for spring flowers in US Department of Agriculture plant resistance zones 8 to 10, the best time is from July to September or October, especially when night temperatures are between 40ºC-50 degrees Fahrenheit or more.

However, the hot and dry Mediterranean climate can allow the planting of bulbs in December and January. Plant the bulbs about 30 to 60 centimeters apart in shallow holes, allowing the rhizomes to settle in the soil when the tips of the leaves point downwards.

For a variety of colors, plant several hybrids and varieties, spacing at least three rhizomes 18 inches apart. Apply organic mulch after autumn planting to protect the young root system.

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I hope this gardening article helps us how to plant, grow, and care iris plants. Also, answer a few questions related to Iris Plants:

  • How to plant, grow Iris plant
  • How to grow Iris Plant
  • How to Plant Iris Plant
  • How to Care Iris plant
  • Where do Irises grow best?
  • Should I deadhead Irises?
  • Do Irises need Sunlight
  • Are Coffee Grounds good for Irises?
  • How many times a year do Irises bloom
  • How fast do Irises spread?
  • Will Irises grow under trees?
  • Should Iris leaves be cut back after blooming?
  • What can I plant next to Iris?
  • Is Epsom salt good for Iris?
  • How often should you water Irises?
  • Why are the leaves on my Iris turning yellow
  • Why are my Irises not blooming
  • Can I transplant Irises in the spring?
  • What causes brown tips on Iris leaves
  • How do you propagate Iris Plants
  • Are Iris poisonous to dogs
  • Can you grow Iris from cuttings?
  • When to plant Iris bulbs