Knowing what plants grow best in Iowa starts with understanding the state’s climate, timing, and growing conditions. In this episode of Howell’s Farm Experience, host Mike Downer sits down with Erin Conner from Howell’s Greenhouse and Pumpkin Patch to talk through the plants, flowers, vegetables, and planting schedules that work well in Central Iowa. Their conversation covers several important takeaways for local gardeners: Iowa is mainly in USDA Hardiness Zone 5, most warm-season plants should wait until after Mother’s Day, perennials and annuals both have a place in a healthy landscape, and local guidance can make a big difference when choosing plants for your yard, patio, or garden.
For homeowners who want more color, better plant survival, and fewer costly mistakes, the biggest lesson is simple: choose plants that match Iowa’s climate and do not rush the season.
Understanding Iowa’s Growing Zone
Erin explains that Central Iowa is generally in USDA Hardiness Zone 5. That means plants need to survive winter temperatures that can fall between negative 10 and negative 20 degrees Fahrenheit.
This matters most when choosing perennials. Since perennials are supposed to come back year after year, they need to be rated for Iowa’s winter conditions. Plants rated for Zones 1 through 5 usually do well here, while Zone 6 plants may struggle because they are better suited for slightly warmer areas.
The good news is that Zone 5 still gives Iowa gardeners plenty of options. Erin mentions popular choices like coneflowers, Black-eyed Susans, hostas, daylilies, peonies, and irises. These plants can bring color, texture, and long-term value to a yard when planted in the right place.
Why Bloom Timing Matters
One helpful point Erin makes is that homeowners should think beyond just picking pretty flowers. They should also think about when each plant blooms.
Mike mentions that he and his wife enjoy hostas because they are hardy and return every year, but their flowers do not last very long. Erin explains that this is where companion planting can help.
By choosing plants with different bloom times, homeowners can keep color going from spring into fall. For example, peonies can bloom earlier in the season, daylilies often bloom in June and July, Black-eyed Susans show up later in summer, and fall bloomers can help finish the season strong.
For gardeners who want consistent color with less planning, annuals are also a great option. Annuals only last one season, but many bloom continuously throughout the growing season.
When to Plant in Central Iowa
One of the biggest gardening mistakes in Iowa is planting too early.
Erin says the typical last frost date in Central Iowa is around May 15, usually near Mother’s Day weekend. Even if April brings a warm stretch, a late frost can still damage tender plants.
That is why Howell’s Greenhouse and Pumpkin Patch recommends waiting until after Mother’s Day before planting warm-season flowers and vegetables outdoors. As Erin notes, spring weather can be unpredictable, and waiting helps protect the plants you have already invested in.
Cool-season crops are different. Potatoes, peas, leafy greens, and beets can often be planted earlier in March or April. But tomatoes and peppers should wait. Peppers especially do not like cold temperatures, and tomatoes can become stunted if planted too soon.
Best Flowers for Iowa Landscapes
For Iowa homeowners looking to add flowers, Erin recommends several reliable choices.
Coneflowers are a favorite because they perform well and support pollinators. Daylilies are another strong option because they are low maintenance, spread easily, and come in many colors.
Irises are especially important at Howell’s Greenhouse and Pumpkin Patch. Erin shares that they have one of the largest iris fields in Iowa, with over 800 varieties. Once established, irises are fairly easy to care for and can make a beautiful addition to a perennial garden.
For shaded areas, hostas are a dependable choice. They come in many shades of green, blue, and white, with different leaf shapes and sizes.
Annuals, Perennials, and Containers
Erin recommends using both annuals and perennials. Perennials provide structure because they return each year. Annuals help fill empty spots and add bright, season-long color.
This balance works well in landscapes, garden beds, and patio containers. Many homeowners use annuals like petunias, million bells, geraniums, or marigolds in pots because they are easy to enjoy up close.
For container gardening, Erin suggests the classic “thriller, filler, and spiller” method. The thriller is the tall focal point, like ornamental grass. The filler adds body, such as lantana or geraniums. The spiller trails over the edge, like sweet potato vine, lysimachia, million bells, or petunias.
For sunny and windy Iowa patios, Erin says ornamental grasses often perform better than taller tropical-looking plants like elephant ears or cannas.
How Howell’s Greenhouse and Pumpkin Patch Helps Local Gardeners
One reason local greenhouse plants can perform better is that they are already adapted to Iowa conditions. Erin explains that Howell’s keeps its greenhouses a little cooler to help acclimate plants before customers take them home.
That means the plants are better prepared for local weather compared to plants shipped in from warmer climates.
Howell’s also helps customers choose plants based on their specific yard. Erin recommends bringing photos, measurements, the direction the area faces, and notes about sun or shade. The more details you provide, the better the team can help you find plants that will actually work.
As Erin says, “Pictures are very helpful.”
Grow a Thriving Iowa Garden with the Right Plants and Timing
A successful Iowa garden comes down to choosing hardy plants, planting at the right time, and building a mix of color, structure, and seasonal interest. For more local advice, watch the full Howell’s Farm Experience episode with Mike Downer and Erin Conner, and visit Howell’s Greenhouse and Pumpkin Patch to learn more about what plants grow best in Iowa.
FAQs About Gardening in Iowa
What is Iowa’s growing zone?
Central Iowa is generally USDA Hardiness Zone 5. Some parts of Iowa may fall into Zone 4, depending on location.
When is the last frost date in Central Iowa?
The typical last frost date is around May 15, usually near Mother’s Day weekend.
When should I plant tomatoes and peppers in Iowa?
Tomatoes and peppers should usually be planted after Mother’s Day. Peppers are especially sensitive to cold weather.
What vegetables can be planted earlier in Iowa?
Cool-season crops like potatoes, peas, leafy greens, and beets can often be planted in March or April.
What flowers grow well in Iowa?
Coneflowers, Black-eyed Susans, daylilies, irises, hostas, and peonies are strong options for many Iowa landscapes.
Are annuals or perennials better?
Both are useful. Perennials come back every year, while annuals provide bright color for one growing season.
What is the best method for patio planters?
The “thriller, filler, and spiller” method works well. Use a tall plant, a full middle plant, and a trailing plant for balance.
Can Howell’s Greenhouse and Pumpkin Patch help with plant choices?
Yes. Bringing photos, measurements, and sun or shade information can help the staff recommend the right plants for your space.
Mike Downer: Hi, everybody! I’m your host, Mike Downer, and I am here with Erin Conner on the Howells Farm Experience. How are we doing today, Erin?
Erin Conner: I’m doing good. Beautiful weather out today.
Mike Downer: It is gorgeous. Today we’re going to be talking about what plants thrive in Iowa and when you should plant them. So my big question for you today, Erin, is: What are the best plants, flowers, and vegetables for Iowa’s climate, and what’s the right planting schedule in Central Iowa?
Erin Conner: One of the most common questions we hear is, “What should we plant?” It really depends on what you want out of your yard or garden because everyone’s goals are different. Some people want color all season long, while others want to save money in the future by planting perennials that come back every year.
You also have to understand Iowa’s growing climate. Iowa is generally in USDA Hardiness Zone 5, although some parts are Zone 4. Here in Central Iowa, we’re Zone 5, where winter temperatures can drop between negative 10 and negative 20 degrees Fahrenheit.
If you’re planting perennials, which come back every year, you need to make sure they’re rated for Zone 5 so they’ll survive the winter.
Mike Downer: So what does USDA Hardiness Zone 5 mean for Iowa gardeners, and how does it affect what and when they should plant flowers and vegetables?
Erin Conner: Zone 5 means plants must be able to survive temperatures between negative 10 and negative 20 degrees Fahrenheit. Plants rated for Zones 1 through 5 will generally do well here.
Plants rated for Zone 6 are better suited for places like Missouri, where winters aren’t quite as harsh.
Even in Zone 5, there are so many beautiful plants to choose from. Coneflowers, Black-eyed Susans, hostas, and many others all thrive here.
Mike Downer: We have a lot of hostas around our house. My wife and I love them because they’re very hardy and come back every year. The only downside is that their flowers don’t last very long.
Erin Conner: That’s where companion planting comes in. You combine plants that bloom at different times of the season. Plant early spring bloomers, then late spring and summer bloomers, followed by flowers that bloom into the fall. That way, you have color throughout the entire growing season.
You can research bloom times or ask your local garden center for recommendations.
Mike Downer: That makes sense.
Erin Conner: For example, peonies bloom in early spring, daylilies bloom in June and July, Black-eyed Susans bloom in late summer, and then you can add fall-blooming flowers to keep the color going.
If that’s more work than you want to do, annuals are another great option because they bloom continuously throughout the growing season.
Mike Downer: I’ve learned something new today.
So when is the last frost date in Central Iowa, and why is it important to wait before planting?
Erin Conner: The typical last frost date in Central Iowa is around May 15, usually around Mother’s Day weekend.
We always recommend waiting until after the last frost before planting outdoors because spring weather can be unpredictable. It might be 80 degrees in April, but then a late frost comes around Mother’s Day and damages everything you’ve planted.
Waiting helps protect your plants.
Mike Downer: That makes perfect sense. I’ve definitely planted too early before and lost some flowers.
So which flowers grow best in Iowa, and what varieties does Howell’s Greenhouse recommend?
Erin Conner: We love plants that support pollinators, so coneflowers are one of our favorites.
Daylilies also grow extremely well in Iowa. They’re low maintenance, spread easily, and come in hundreds of colors.
We’re especially partial to irises because we have one of the largest iris fields in Iowa, with over 800 varieties. Once established, they’re very easy to care for.
If you’re looking for later-season flowers, coneflowers are excellent.
For shady areas, hostas are a great choice. They come in many shades of green, blue, and white, with a wide variety of leaf shapes and sizes.
Mike Downer: Maybe you can answer a question for me. We have these little purple flowers that seem to spread everywhere…
Erin Conner: Are they in sun or shade?
Mike Downer: They’re green with little purple cone-shaped flowers. They bloom in early spring and fade around the Fourth of July.
Erin Conner: That could be several different plants. I’d really need to see a picture to identify it.
Mike Downer: Fair enough.
When should Central Iowa gardeners plant tomatoes, peppers, squash, herbs, and lettuce for the best results?
Erin Conner: Cool-season crops like potatoes, peas, leafy greens, and beets can be planted much earlier—even in March or April.
Tomatoes and peppers should wait until around Mother’s Day. Peppers especially dislike cold weather. Tomatoes can tolerate cooler temperatures better, but cold weather can stunt their growth.
For the healthiest plants, wait until after Mother’s Day before planting tomatoes and peppers.
Mike Downer: What’s the difference between annuals and perennials, and how can homeowners create a good balance?
Erin Conner: Perennials come back every year, while annuals only last one season.
I recommend using both. Plant perennials throughout your landscape for long-term structure, then fill open spaces with annuals like petunias or million bells for season-long color.
Many people also grow annuals in patio containers because they’re easy to maintain and provide vibrant color.
Mike Downer: My wife definitely loves her pots full of marigolds.
What are the best plants for container gardening on Iowa patios and porches, especially in sunny, windy locations?
Erin Conner: We specialize in container gardening and patio planters.
I always recommend using the “thriller, filler, and spiller” approach.
The thriller is your tall plant, like ornamental grasses. In windy locations, grasses perform better than elephant ears or cannas.
The filler adds body, such as geraniums or lantana.
The spiller trails over the edges of the pot, like sweet potato vine, lysimachia, million bells, or petunias.
There are endless combinations, making patio containers a lot of fun to design.
Mike Downer: The color choices really are amazing.
What are the most common gardening mistakes Iowa homeowners make?
Erin Conner: The biggest mistake is planting too early.
People get excited after a warm spell in April and rush to plant everything. Then Mother Nature reminds us it’s still spring.
We recommend shopping in late April, planning your containers, and holding onto the plants until after Mother’s Day. Bring them in and out of the garage as needed until it’s safe to plant outdoors.
Mike Downer: That definitely happens here in Central Iowa.
How does Howell’s Greenhouse help gardeners succeed with plants adapted to Iowa’s climate?
Erin Conner: We acclimate our plants by keeping our greenhouses a little cooler. That way, they’re better prepared for Iowa conditions when customers take them home.
They’re much hardier than plants shipped directly from warmer climates.
Mike Downer: So if I’m a first-time homeowner or someone who doesn’t know much about gardening, your staff can help me figure everything out?
Erin Conner: Absolutely. Our staff has extensive knowledge about plants and where they’ll perform best.
If you want ready-made patio planters, we have large, beautiful containers that are unique and unlike what you’ll find at big-box stores.
Mike Downer: That’s great because my neighborhood yards all tend to look alike since everyone shops at the same stores.
If I brought you pictures of my landscaping, could you help me improve it?
Erin Conner: Definitely. Pictures are very helpful.
It also helps if you know the dimensions of the area and which side of the house it faces, along with how much sun or shade it receives.
The more information you bring us, the better we can help.
Mike Downer: Sounds like you’ve got everything covered.
Thanks again, Erin, for educating me and all of our listeners about gardening in Iowa and helping everyone have a successful growing season.
As always, it’s great talking with you, and I look forward to our next conversation.
Erin Conner: Can’t wait!
Mike Downer: Thanks a lot, Erin. Have a great day.
Erin Conner: Thank you.
