How to Plant Iris Corms: Tips for a Successful Garden


Greetings to all plant lovers! In this article, we will guide you on how to plant iris corms successfully. Irises are beautiful and vibrant flowers that bloom when planted correctly. Planting iris corms may seem like a daunting task at first, but it is quite simple when you understand the steps and follow them accordingly. Below we will take you through the steps, explanations and tips for planting iris corms, so let’s get started!


Step 1: Choose the Right Variety of Iris Corms

Before planting, you need to choose the right variety of iris corms. Irises come in many varieties, each with unique colors, shapes, and sizes. Determine which variety you want to plant, and then purchase corms of that specific variety from a reputable dealer. Ensure that the corms are healthy, firm, and plump.

Step 2: Prepare the Soil

Irises thrive in well-draining soil. Prepare the soil by clearing the area of weeds, rocks, and other debris. Loosen the soil to a depth of 12 inches using a garden fork or shovel. Incorporate some organic matter, such as compost or peat, to enrich the soil. This provides the nutrients required to spur growth during planting and beyond.

Step 3: Choose a Planting Location

Irises need at least six hours of full sunlight each day. Therefore, it is necessary to choose a site that receives adequate sunlight for the new plants to thrive. Ensure that the planting location also has adequate drainage to avoid waterlogging.

Step 4: Dig Holes for the Corms

Use a trowel or gardening spade to dig holes that are eight inches deep and eight inches apart in the prepared soil. A good rule of thumb is to make the holes twice the height of the corms. If you are planting dwarf or miniature irises, the holes should be 4 to 6 inches deep.

Step 5: Place Corms in the Holes

Place the iris corms carefully in the holes. Space the corms at least six inches apart if you intend to plant multiple varieties. Ensure that the pointed ends of the corms face upwards, and the basal plate rests at the bottom of the hole.

Step 6: Cover the Corms

After placing the corms in the holes, cover them with soil, and pat gently. Ensure that the soil is lightly pressed around the corms to eliminate air pockets. Leave a slightly elevated hill in the middle of each hole to improve water runoff.

Step 7: Water the Corms

Gradually water the newly planted iris corms gently while avoiding excess water. The corms should be moist, but the soil should not be waterlogged. A good rule of thumb is to water moderately once a week, especially during the growing season.

Step 8: Mulch the Area

After planting is complete, spread a layer of organic mulch around the planting bed, keeping it at least two inches away from the stems. This will help retain soil moisture, suppress weeds and keep the corms protected as they establish themselves.

Step 9: Watch for Germination

Monitor the planting area regularly for signs of germination. Most iris corms can take four to six weeks to sprout, but the growth rate varies from one variety to another.

Step 10: Maintain the Plants

Once the irises have germinated, continue to care for them by ensuring they get enough water, sunlight, and fertilizer. Water them whenever the soil starts to feel dry, but avoid excessive watering as it can make the soil waterlogged. Additionally, fertilize the irises once in the spring before the first bloom. This will provide them with the necessary nutrients for a healthy growth cycle.

Step 11: Deadhead the Flowers

As the irises bloom, pinch off faded flowers to promote new growth. Remove the stalks when they are entirely spent by cutting them off at the base. Removing spent flowers helps the irises focus their energy on producing more buds.

Step 12: Divide the Corms

After about three or four years, irises may produce too many corms, making them congested in one area. To correct this problem, gently dig up the overcrowded and mature plants then divide them into smaller sections. Ensure that each section has a healthy corm and set the divisions six inches apart.

Step 13: Protect from Pests and Diseases

Irises are generally resistant to pests and diseases. However, some pests like aphids, spider mites, and thrips may invade and cause damage to the iris plants. Monitor the plants for signs of infestation, and treat with appropriate insecticides or repellents if necessary.

Step 14: Adhere to the Climate Zone Guidelines

Ensure that you plant irises in the appropriate climate zone for your area. This is because the climatic conditions and temperature requirements vary from variety to variety. Adhering to the zone guidelines will provide your irises with the ideal growing conditions for optimal growth.

Step 15: Enjoy Blooms

Patience and persistence are key when growing irises. It may take at least two years for newly planted irises to produce blooms, but the wait is definitely worth it. Once they bloom, you’ll enjoy their vibrant colors and beautiful petal formations. With proper care and maintenance, irises can bloom for several years.

Explanations and Tips

Tip 1: Watering Requirements

It’s important to maintain the soil moisture level, especially for newly planted corms. A lack of moisture can slow growth while excess water can lead to corm rot. Maintain soil moisture by watering once a week during the growing season.

Tip 2: Fertilize Regularly

Irises require low doses of nitrogen-based fertilizer. Apply a low-nitrogen fertilizer once in spring before the first bloom. Avoid over-fertilization as it can affect the corms’ growth adversely.

Tip 3: Planting Depth

Plant the corms at the appropriate depth to ensure that they are adequately protected from frost and cold temperatures. Plant them at a depth of at least two inches to protect them from cooling temperatures.

Tip 4: Dividing Corms

Dividing iris corms prolongs plant life and prevents overcrowding, resulting in healthier plants. It’s best to divide when plants become extremely large or every three to four years. Dividing commonly occurs after the blooming period in late summer/early fall.

Tip 5: Avoid Overcrowding

Densely planted corms can become overcrowded and compete for nutrients. This can lead to stunted growth, weak stems, and small blooms. Adequately space the corms at least six inches apart to avoid overcrowding and promote healthy growth.

Tip 6: Irrigation and Drainage

Irrigation and drainage are critical factors in the success of iris planting. Ensure that the soil adequately drains to prevent waterlogging, which can lead to root rot. Proper drainage makes it easy to control irrigation, ensuring that the irises receive just enough water.

Tip 7: Don’t Cover the Corms with Mulch

Avoid covering the corms with too much mulch, as this can lead to moisture retention and rot. Leave a slight space between the corms and the mulch to promote better moisture circulation and aeration.

Tip 8: Prepare Ahead of Planting

It’s essential to prepare the planting area beforehand to ensure that they develop strong root systems. Ensure that the soil is loosened to a depth of at least 12 inches, hedges and shrubs are cut back, and weeds and debris are removed.


And that’s it – a comprehensive guide on planting iris corms is complete. By following the steps outlined above and incorporating the tips and tricks, you should have beautiful, healthy irises blooming in no time. Remember to give your irises adequate care and maintenance to promote healthy growth. Good luck, and happy planting!

Strengths and Weaknesses of Planting Iris Corms


Planting iris corms have several advantages, some of which are:

Advantages Details
Low Maintenance Iris plants require very little attention once established.
Fast Growth Under the right conditions, iris corms can produce blooms in as little as 2-3 months.
Color Variety Iris flowers are available in a wide array of colors, making them versatile for many landscaping designs.
Perennial Most iris varieties are perennial, meaning that they will come back year after year, saving you money and time from replanting.


While there are many advantages to planting iris corms, there are also some disadvantages:

Disadvantages Details
Prone to Pests and Diseases Iris plants are known to be particularly susceptible to pests such as iris borers and diseases such as root rot, which can be difficult to manage.
Seasonal Blooming Iris flowers typically bloom for a short period of time during the spring and early summer months, leaving the plant looking lackluster for the remaining months of the year.
Requires Soil Preparation Before planting iris corms, one should prepare the soil by adding organic matter to improve drainage and nutrient content. This can be time-consuming and may require additional resources.
Spacing Considerations Iris plants require adequate spacing between them to prevent root competition and crowding, which can cause stunted growth and poor performance.

Despite the disadvantages of planting iris corms, the advantages far outweigh the potential drawbacks. With proper care and maintenance, iris plants can provide a beautiful and vibrant addition to any garden or landscaping design.


Q1. What are iris corms?

A1. Iris corms are a type of bulbous plant that produce flowers. They are a small, rounded structure that stores food and nutrients for the plant.

Q2. When is the best time to plant iris corms?

A2. The best time to plant iris corms is in late summer or early fall, before the first frost.

Q3. What is the ideal location to plant iris corms?

A3. Iris corms should be planted in a sunny location with well-draining soil. Avoid planting in areas that are prone to standing water or heavy shade.

Q4. How deep should iris corms be planted?

A4. Iris corms should be planted with the top of the corms near the surface of the soil, around 1 to 2 inches deep.

Q5. How far apart should iris corms be planted?

A5. Iris corms should be planted 6 to 8 inches apart, depending on the variety.

Q6. How much water do iris corms need?

A6. Iris corms need regular watering until they become established. After that, they can tolerate periods of drought but should be watered during long dry spells.

Q7. Do iris corms need fertilizer?

A7. Iris corms benefit from a balanced fertilizer applied in the spring or late summer, before the new growth appears.

Q8. What is the best way to protect iris corms from pests?

A8. Iris corms are susceptible to damage from pests such as iris borers and thrips. Apply an insecticide in the spring or early summer to prevent damage.

Q9. When do iris corms bloom?

A9. Iris corms bloom in the spring or early summer, depending on the variety.

Q10. How do I deadhead iris plants?

A10. Deadhead iris plants by cutting the flower stalk down to the base of the plant after the blooms have faded.

Q11. When should iris corms be divided?

A11. Iris corms should be divided every 3 to 4 years to prevent overcrowding and encourage healthy growth.

Q12. How do I divide iris corms?

A12. To divide iris corms, carefully dig up the plant and separate the corms into individual pieces. Replant the corms in a new location or pot.

Q13. Can iris corms be grown in containers?

A13. Yes, iris corms can be grown in containers. Choose a large pot with well-draining soil, and plant the corms with the top of the corms just below the soil surface. Water regularly and fertilize as needed.


In conclusion, planting iris corms is an easy process that can be accomplished by anyone with a little bit of gardening experience. Before starting, it’s important to select the right location with good soil drainage and ample sunlight. Additionally, make sure to choose healthy corms and plant them at the right depth, allowing enough space between them. Remember to water them well and keep the soil moist but not waterlogged. Once the plants start growing, provide some support if necessary, and remove any dead leaves or flowers to prevent disease. With a little bit of care and attention, your iris corms should produce beautiful flowers for many years to come.

Overall, planting iris corms can be a rewarding experience for both novice and experienced gardeners. Not only are irises beautiful to look at, but they also come in a variety of colors and sizes, making them a versatile addition to any garden. By following the tips outlined in this guide, you should be well on your way to planting your own iris corms and enjoying their stunning blooms. So get out there, get your hands dirty, and start planting!