What Planting Zone is Illinois?

Illinois, located in the Midwest region of the United States, experiences a diverse climate that affects the success of various plants. Understanding the planting zone for Illinois is crucial for gardeners, farmers, and anyone interested in cultivating plants. In this article, we will explore the different planting zones in Illinois and provide valuable information to help you make informed decisions about what to plant and when.

Introduction: Importance of Planting Zones

Planting zones, also known as hardiness zones, play a vital role in determining which plants can thrive in specific regions. These zones are defined based on the average minimum winter temperatures of an area, helping gardeners identify which plants are most likely to survive and thrive in their particular climate.

Understanding Plant Hardiness Zones

The United States Department of Agriculture (USDA) developed the Plant Hardiness Zone Map, which divides the country into different zones based on temperature ranges. Each zone represents a ten-degree Fahrenheit difference in the average annual minimum temperature. By referencing this map, gardeners can choose plants that are well-suited to their local climate and avoid potential losses due to extreme temperatures.

Climate and Geography of Illinois

Before delving into the specific planting zones in Illinois, it’s essential to understand the state’s climate and geography. Illinois has a diverse climate, with distinct seasonal variations. It experiences hot and humid summers, cold winters, and moderate spring and fall seasons.

The geography of Illinois also varies, with the northern part of the state being cooler and receiving more precipitation compared to the southern region. The central part of Illinois is characterized by flat prairies, while the southern part features rolling hills.

Planting Zones in Illinois

Illinois is divided into different planting zones, ranging from Zone 5b in the north to Zone 7a in the southernmost regions. Let’s explore the different planting zones in Illinois:

Zone 5b

Zone 5b covers the northernmost parts of Illinois, including cities like Chicago and Rockford. This zone experiences cold winters, with average minimum temperatures ranging from -15°F to -10°F (-26°C to -23°C). Gardeners in this zone should choose plants that can tolerate and survive freezing temperatures.

Zone 6a

Zone 6a encompasses central Illinois, including cities like Peoria and Bloomington. This zone experiences milder winters compared to Zone 5b, with average minimum temperatures ranging from -10°F to -5°F (-23°C to -21°C). Plants suitable for Zone 6a should be able to withstand moderately cold temperatures.

Zone 6b

Zone 6b covers parts of central and southern Illinois, including cities like Springfield and Carbondale. This zone experiences slightly warmer winters compared to Zone 6a, with average minimum temperatures ranging from -5°F to 0°F (-21°C to -18°C). Gardeners in Zone 6b can grow a wider variety of plants compared to the colder zones.

Zone 7a

Zone 7a represents the southernmost parts of Illinois, including cities like Cairo and Metropolis. This zone experiences mild winters, with average minimum temperatures ranging from 0°F to 5°F (-18°C to -15°C). Gardeners in Zone 7a can grow a broader range of plants, including some that are more sensitive to cold temperatures.

Best Plants for Each Zone

Each planting zone in Illinois has its own set of suitable plants. Here are some examples of plants that thrive in each zone:

  • Zone 5b: Peonies, daylilies, hostas, and Siberian iris.
  • Zone 6a: Bee balm, coneflowers, black-eyed Susans, and ornamental grasses.
  • Zone 6b: Japanese maples, hydrangeas, lavender, and phlox.
  • Zone 7a: Crepe myrtles, camellias, southern magnolias, and fig trees.

These are just a few examples, and there are many other plants that can be successfully grown in each zone. It’s important to research specific plants to ensure they are suitable for your zone and meet your gardening preferences.

Factors Affecting Planting Success

While planting zones provide a useful framework, several other factors can influence the success of your garden. Here are some key considerations:

  1. Soil Type: Understanding the composition and pH of your soil is crucial for selecting plants that can thrive in those conditions.
  2. Sunlight: Different plants have varying sunlight requirements, so it’s important to choose plants that match the amount of sunlight your garden receives.
  3. Watering Needs: Some plants require more water than others, so consider the water requirements of your chosen plants and ensure they align with your watering capabilities.
  4. Microclimates: Your garden may have microclimates that differ from the overall planting zone, so observe these variations and choose plants accordingly.

Tips for Successful Gardening in Illinois

To help you achieve a successful garden in Illinois, here are some tips to consider:

  1. Select Zone-Appropriate Plants: Choose plants that are well-suited to your specific planting zone to increase their chances of thriving.
  2. Amend the Soil: Test your soil and make necessary amendments to ensure it has the right balance of nutrients and pH levels.
  3. Mulch and Compost: Apply organic mulch around your plants to retain moisture, suppress weeds, and improve soil health.
  4. Provide Adequate Watering: Water your plants regularly, especially during dry periods, and avoid overwatering or underwatering.
  5. Practice Crop Rotation: If you have a vegetable garden, rotate your crops each year to prevent soil depletion and minimize pest and disease problems.

By following these tips and understanding the unique characteristics of your planting zone, you can create a thriving garden in Illinois.


Understanding the planting zones in Illinois is essential for successful gardening. By selecting plants that are well-adapted to your specific zone, considering the climate and geography of the region, and addressing other factors that influence planting success, you can create a beautiful and productive garden. Enjoy the process of gardening in Illinois, and may your green thumb flourish!


Q: Can I grow citrus trees in Illinois? A: Citrus trees are not suitable for the Illinois climate due to their sensitivity to cold temperatures. They require a warmer climate and are better suited for regions with milder winters.

Q: Are there any perennials that can survive in Zone 5b? A: Yes, several perennials can thrive in Zone 5b, including peonies, daylilies, hostas, Siberian iris, and black-eyed Susans.

Q: When is the best time to start planting in Illinois? A: The best time to start planting in Illinois depends on the specific plant and your planting zone. Generally, it’s advisable to wait until the risk of frost has passed, which is typically around mid to late spring.

Q: Can I grow palm trees in Zone 6a? A: Palm trees are not suitable for Zone 6a due to their sensitivity to cold temperatures. They require a warmer climate, typically found in Zones 9 and above.

Q: How can I protect my plants from harsh winter conditions in Illinois? A: To protect your plants from harsh winter conditions, you can use techniques such as mulching, providing adequate insulation, and covering plants with protective materials like burlap.

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