Indiana Growing Zones Explained

Indiana Growing Zones Explained

Gardeners, landscapers, and anyone involved in farming know that not all plants can grow in their area. This is because different areas have varying climatic conditions, and only plants that are accustomed to those conditions can survive.

Indiana state experiences different climatic conditions, which are defined by USDA hardiness zone classifications. In this piece, we’ll break down the various growing zones here and help you know which plants are suitable for this area.

How to Know your Indiana Growing Zone

The USDA plant hardiness zone map is used by gardeners and landscapers to determine which plants are likely to thrive in a particular area. 

One way to figure out your hardiness zone is to use the USDA Hardiness Zone Map. The online version gives you a map based on your ZIP code or state. You can also get hardiness zone information from seed packets, which often use the same map.

This interactive map can help you determine your hardiness zone. To do this, simply select the state from the search area, and it will provide you with all of the growing zones in that particular state. If you need more precise results, use your zip code to give you a more accurate map of your area.

Indiana’s Growing Zones

Indiana is among the top ten largest farming states in the US, with over 14 million acres in operation. The USDA Hardiness Zone Map divides North America into 13 distinct growing zones. Each zone is 10°F warmer (or colder) than the adjacent zone.

For instance, zone 4 is 10°F warmer than zone 3 and 10°F colder than zone 5. These are the average minimum temperatures during winter. Indiana has two USDA Hardiness Zones, which are 5 and 6. The state falls into either zone 5b, 6a, or 6b.  Zone 5a includes most of the northern and central parts of the state, while Zone 6 includes southern Indiana.

As a gardener, you will undoubtedly want to have a thriving garden full of all your favorite plants. But that can be tricky, as some plants cannot survive below a specific minimum temperature. 

USDA plant growing zones in Indiana Minimum temperature(°Fahrenheit)
5b -15 to -10°F
6a -10 to -5°F
6b   -5 to 0°F

Indiana’s Growing Zone 5b

Cabbage

Zone 5 has two subsets – 5a and 5b. They correspond to the different levels of cold weather in Zone 5. Knowing the designation for a plant before you buy it can help you choose the right plant that will survive in your climate. The average date of the last frost in zone 5b is around April 15 – May 15. The first frost appears on October 15.

Plants That Thrive in Indiana’s Zone 5b

Zone 5 gardeners usually wait until late spring to plant their vegetable gardens or annuals. One exception is that vegetables need to be grown sooner in climates threatened by a late frost. Annuals and vegetables do well in zone 5 but may die off quickly if they get too cold. Many tough perennials can withstand late frosts and will stay dormant until it is warmer in early spring.

Vegetables to Plant in Indiana’s Zone 5b and When to Plant Them

Planting for zone 5b starts in March and continues until October. Your earliest vegetables for this zone, which you should plant in March and April, include:

  • Cabbage
  • Brussels sprouts
  • Carrots
  • Cauliflower
  • Beets
  • Broccoli 
  • Kale
  • Kohlrabi
  • Lettuce
  • Mustard
  • Asparagus
  • Peas
  • Potatoes
  • Radishes
  • Rhubarb
  • Spinach
  • Swiss chard
  • Turnips

Between April to June, you can plant the following vegetables.

Cucumber

  • Cucumber
  • Eggplant
  • Endive
  • Leeks
  • Muskmelon
  • Watermelon
  • Pepper
  • Pumpkin
  • Rutabaga
  • Summer and winter squash
  • Tomato
  • Celery
  • Chives
  • Okra
  • Onions
  • Parsnips

Growing vegetables can be a year-round endeavor. True, some plants such as tomatoes and cucumbers grow best in the summer heat, but you can sow many hearty veggies in the cold months that will grow into delicious harvests come springtime. These include:

  • Mache
  • Claytonia greens
  • Leeks
  • Carrots
  • Spinach 
  • Collards
  • Parsnips
  • Lettuce
  • Cabbage
  • Turnips
  • Swiss chard
  • Jerusalem artichokes
  • Red-skinned potatoes

Best Perennials to Plant in Indiana’s Zone 5b and When to Plant Them

Daylily

Zone 5 is one of the colder zones in the country. In winter, snow provides a blanket of insulation for plants which protects them from frost. Some perennials and bulbs can withstand zone 5b winters. Some bulbs even grow naturally in zone 5. You can plant your zone 5b perennials after the last frost, which occurs in mid-April. Here are some gorgeous zone 5b perennials and bulbs for your garden.

  • Daylily
  • Hibiscus
  • Lavender
  • Shasta Daisy
  • Blazing Star
  • Bee balm
  • Catmint
  • Poppy
  • Hollyhock
  • Yarrow
  • Penstemon 
  • Russian Sage 
  • Garden Phlox 
  • Creeping Phlox 
  • Black-Eyed Susan 
  • Salvia
  • Wormwood
  • Butterfly weed/Milkweed
  • Aster
  • Baptisia
  • Bachelor’s Button
  • Dianthus 
  • Coneflower 
  • Joe Pye weed 
  • Filipendula 
  • Blanket flower 

Zone 5b Bulbs

  • Hyacinths
  • Crocus
  • Alliums
  • Lilies
  • Irises
  • Muscari 
  • Tulips
  • Lily-of-the-valley
  • Scilla
  • Daffodils

Best Annuals to Grow in Indiana’s Zone 5b and When to Plant Them

Marigold

Annuals are plants that grow and die within one year. They sprout from seed, form flowers, set seed, and die all in the span of one season.

Zone 5 and lower areas often use annuals because they can’t bear the cold winters to sustain perennial plants. The best time to plant your annual flowers in zone 5b is early to mid-May, after the last frost. Here’s a list of the best zone 5b annuals for your garden.

  • Marigold
  • Zinnia
  • Dusty Miller
  • Snapdragon
  • Geraniums
  • Lantana
  • Petunia
  • Calibrachoa
  • Begonia
  • Alyssum
  • Bacopa
  • Cosmos
  • Gerbera Daisy
  • Impatiens
  • Sunflower
  • Cannas
  • Elephant Ear
  • Mums
  • Cleome
  • Four O’ Clocks
  • Cockscomb
  • Torenia
  • Nasturtiums
  • Moss Roses

Gardening Tips for Farmers in Indiana’s Zone 5b

  • You can increase the growing timeframe with a few tricks, such as raised beds that keep soil warmer than field crops or hoop tunnels over beds/rows. Another way to help plants grow is to plant them in cold frames.
  • You may notice that some packets and containers of seeds and plants say they take a certain number of days to mature. Plan your garden by looking at these numbers, as they represent the time it will take from sowing the seeds to harvesting or blooming.
  • It is crucial to start your seeds indoors. You should start them at least six weeks before the last frost date or even earlier if possible. Doing this will make sure your plants have enough time to grow and mature.

Indiana’s Growing Zone 6a

Tomato

This zone has a medium-length growing season, and the risk of frost is minimal. For this reason, you can plant most vegetables without fear that they won’t grow before the first frost date. The last frost date for Zone 6a is May 1, while the first frost date is November 1. The minimum annual temperature for Zone 6a is -5°F.

Plants That Thrive in Indiana’s Zone 6a

Gardening in USDA zone 6a is a beautiful experience. You may have to start some seedlings inside around March and bring them outside in May when the weather warms up. Nevertheless, you can expect a long and productive season with many plants that flourish in your climate.

Vegetables to Grow in Indiana’s Zone 6a and When to Plant Them

Spring vegetable planting can be done in zone 6a anytime between mid-March and mid-November. However, it’s essential to remember that these are just guidelines because the seasons can fluctuate year to year. Hare are some of the best vegetables that will thrive in your zone 6a garden.

  • Cabbage
  • Cauliflower
  • Tomato
  • Eggplant
  • Peppers
  • Cucumber 
  • Brussels sprouts
  • Kale
  • Onions
  • Celery
  • Spinach
  • Broccoli
  • Radish
  • Peas
  • Carrots
  • Lettuce
  • Beets
  • Potatoes
  • Squash
  • Sweet potatoes

Best Perennials to Grow in Indiana’s Zone 6a and When to Plant Them

Helianthus Happy Days

Perennials are beautiful plants that keep blooming year after year. Any perennial suitable for this zone can withstand climates that are cooler or hotter than zone 6a. You can plant them around mid-March (after the last frost) and continue all through to mid-November. Some of the best zone 6a perennials are listed below.

  • Helianthus Happy Days
  • Bee balm
  • Papaver Orientale Turkish Delight
  • Coneflower
  • Fritillaria Meleagris
  • Salvia
  • Campanula Samantha
  • Daisy
  • Monarda Blue Moon
  • Lupinus purple swirl
  • Daylily
  • Aconitum Napellus Monkshood
  • Coral bells
  • Echinacea Julia Coneflower
  • Hostas
  • Hellebore
  • Viola Sorbet Lemon Blueberry Swirl
  • Achillea fanal
  • Iris cloud bullet
  • Dianthus fire and ice
  • Anemone Wild Swan
  • Geum Triflorum
  • Ajuga Reptans Bronze Beauty

Best Annuals to Grow in Indiana’s Zone 6a and When to Plant Them

Calibrachoa

Whether planted in a garden, a flower bed, or containers, annuals are more likely to survive if not planted too early. If that is the case, they have a higher risk of being damaged or killed by cold snaps.

Planting around Mother’s Day is a good idea because it gives you an entire growing season, meaning that the plant will be mature and grow to its full size by the time summer hits. Below are some of the best zone 6a annuals to choose from.

  • Calibrachoa
  • Cleome
  • Cockscomb
  • Cosmos
  • Angelonia
  • Heliotrope
  • Impatiens
  • Lantana
  • Lobelia
  • Marigold
  • Pansy
  • Torenia
  • Verbena
  • Petunia
  • Snapdragons
  • Strawflower
  • Sunflower
  • Sweet Alyssum
  • Bacopa
  • Begonia
  • Four O’Clocks
  • Fuchsia
  • Geranium
  • Mexican Heather

Gardening Tips for Farmers in Indiana’s Zone 6a

  • Start your warmer weather crops indoors, eight weeks before transplanting them outdoors.
  • You can grow vegetables from March to November. You’ll plant cool-weather crops during March and when it cools off again in the fall. 
  • In the beginning, you should start with vegetables such as lettuce, radishes, and other root vegetables. At the end of your season, you can end with the same types of vegetables.
  • To extend your growing season, consider using raised beds or a greenhouse.

Indiana’s Growing Season 6b

Beets

All plants have specific zones where they grow best. Zone 6b’s average winter temperature is -5 to 0 Fahrenheit, which is just a little warmer than other areas. The last frost date for Zone 6b is between early to mid-April, but the first frost starts around the middle to late October.

Plants That Thrive in Indiana’s Zone 6b

You’ll probably have several microclimates in your Zone 6b garden, which means different plants will thrive in each of them. These microclimates may result from shade from a building, direct sunlight, or plants growing under a tree. 

For you to plant a successful garden, you’ll need to take this into account. If you spend a little time determining the microclimates in your yard or garden, choosing the right plants to thrive in the specific spots will be easy.

Vegetables That Thrive in Indiana’s Zone 6b and When to Plant Them

When you grow vegetables in zone 6b, utilize cool weather in spring and fall to your advantage. One idea is to plant frost-resistant veggies like kale and parsnips late in the season for a more extended harvest.

Late summer planting will get you tasty vegetables long into autumn. Starting them in spring several weeks before the last frost will also work. Here’s a list of vegetables suitable for zone 6b.

  • Beets
  • Carrot
  • Chards 
  • Kale
  • Onions
  • Celery
  • Spinach
  • Brussels sprouts
  • Cabbage
  • Cauliflower
  • Tomato
  • Eggplant
  • Peppers
  • Melons
  • Turnips
  • Parsley
  • Basil 
  • Cucumber
  • Corn
  • Dry beans
  • Broccoli
  • Radish
  • Peas

Best Perennials to Grow in Indiana’s Zone 6b and When to Grow Them

Solomon's seal

Zone 6b is an ideal place for those who love hardy perennials. The summer season in this zone is moderately long, and the winters are cold enough to keep any stray plants healthy. Planting these perennials in September is great, as they prefer cooler weather and a more extended growing season. Below are some outstanding perennials for this zone.

  • Jack frost
  • Solomon’s seal
  • Bleeding heart
  • Bee balm
  • Coneflower
  • Lenten roses
  • Salvia
  • Astilbe 
  • Daisy
  • Japanese painted fern
  • Daylily
  • Joe Pyweed
  • Creeping jenny 
  • Coral bells
  • Catmints
  • Black-eyed Susans
  • Hostas
  • Hellebore
  • Lambs ear

Best Annuals to Grow in Indiana’s Zone 6b and When to Plant Them

Petunia

Different annual plants need different types of care. Some need sun, and some need lots of shade. For the best results, read plant tags or seek advice from the garden center workers about the specific needs of each plant before planting or transplanting.

Since the last frost occurs around April 20 to May 20, waiting until Mother’s Day would be the best time to plant your annuals. Here’s a list of annuals for zone 6b gardeners.

  • Petunia
  • Snapdragons
  • Strawflower
  • Sunflower
  • Sweet Alyssum
  • Torenia
  • Pansies
  • Strawflowers
  • Calendulas
  • Bacopa
  • Begonia
  • Calibrachoa
  • Cleome
  • Bee balm
  • Cress
  • Euphorbia
  • Heliotrope
  • Impatiens
  • Lantana
  • Lobelia
  • Marigold
  • Rattle poppy
  • White frills
  • Mexican Heather
  • Moss Rose
  • Nasturtium
  • Nemesia

Gardening Tips for Farmers in Indiana’s Zone 6b

Nemesia

  • If your zone is 6b, you should start seeds indoors six weeks before the last frost date. This includes plants like tomato, eggplant, and pepper.
  • Planting your vegetables early in the season may be helpful. You can grow direct sow cabbage, beans, corn, cucumber, squash, and other veggies from around May 1.
  • To prolong your growing season, consider using raised beds and greenhouses.

FAQs

Question: How Many Plant Hardiness Zones are in Indiana?

Answer: Indiana only has two USDA plant hardiness zones, which are 5 and 6. The further south you go in the state, the higher the temperature and the more extreme the zone. Some parts of the state are Zone 6, as well as part of the northwest corner.

Question: How is Zone 6a Different from Zone 6b?

Answer: Zone 6a is a little colder than zone 6b. The average winter temperature in zone 6a is -10 to -5 Fahrenheit, and the average winter temperature in zone 6b is -5 to 0 Fahrenheit. All plant packets list the area where the particular plant grows best. Since the temperature difference isn’t that much, plants may survive in either zone 6a or 6b.

Question: What Crops Can You Plant in April in Indiana?

Answer: Much of the joy of gardening comes from experimenting with new plants. One way to do this is by directly seeding seeds in the ground, perfect for plants like peas, lettuce, spinach, carrots, beets, turnips, parsnips, and Swiss chard.
Transplants are also options for cool-season crops like broccoli, cauliflower, cabbage, Brussels sprouts, kohlrabi, and onions. You can also transplant or plant rhubarb crowns and asparagus.

Question: What is the Best Time to Plant Annuals in Indiana?

Answer: Plant warm-season annuals after frost. In Southern Indiana, that means from late April to early May. In Northern Indiana, that means from mid-May. You can also plant fall-flowering bulbs and perennial flowers in the spring.

Conclusion

Most of Indiana is in hardiness zone 5a, with the rest falling into zone 6. Gardeners should find out more about the area’s climate as it will help them determine which plants will thrive in your region.

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