Best Planting Times for Soybeans in Iowa

Planting MethodActivityRecommended Dates
Outdoor PlantingIndoor Seed StartingApril 15 – May 15
Transplant OutdoorsMay 20 – June 5
Greenhouse PlantingYear-roundAdjust planting based on temperature control in the greenhouse

Planting Conditions

Soybean Planting Conditions

Iowa’s climate is categorized as humid continental, providing a favorable environment for soybean cultivation. With USDA Hardiness Zones ranging from 4a to 6a, growers can expect optimum growing conditions during the warm summer months.

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Useful Tools for Starting Soybeans Indoors

Using the right tools can save you time and enhance your success rate.

Seeds

Quality seeds lead to better germination and healthier plants. Starting with high-quality seeds gives your soybeans the best chance to thrive from the very beginning.
Soybean Seeds
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Planting Trays

Planting trays help you organize your seedlings and ensure they have enough space to grow before transplanting them outdoors. This makes the process more efficient and increases the chances of strong, healthy plants.
Planting Trays Image
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Grow Lights

Grow lights are essential if you don’t have enough natural sunlight. They provide your seedlings with the light they need to grow strong and healthy, even in less-than-ideal conditions.
Grow Lights Image
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Seed Starting Soil

Using light, fine soil specifically designed for seed starting helps young roots establish quickly and promotes healthy growth. It’s an easy way to give your seedlings the best start possible.
Seed Starting Soil Image
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Greenhouse Growing

In Iowa, a greenhouse can protect soybean plants from unpredictable weather conditions and pests. It also extends the growing season, allowing for earlier planting in spring and later harvesting in fall.

Consider investing in a 10×12 FT Greenhouse priced at $1,199 to ensure your soybeans thrive in a controlled environment.
Greenhouse Image 1
Greenhouse Image 2
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Fertilizer

For optimal soybean growth in Iowa, supplementing with fertilizer can ensure abundant and healthy harvests. Quality fertilizer helps replenish nutrients in the soil and promotes vigorous plant growth.
Fertilizer Image
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Plant soybeans outdoors in Iowa approximately 1-2 weeks after the last spring frost date, ensuring the soil is warm enough for optimal growth.

Average Last Frost Dates for Iowa’s Major Cities

CityAverage Last Frost Date
Des MoinesApril 30
Cedar RapidsMay 5
DavenportApril 25
Sioux CityMay 10
Iowa CityMay 3

Disclaimer: Frost dates are average estimates, and actual conditions may vary. It is recommended to monitor local forecasts and adapt planting decisions accordingly.

Other planting guides for Iowa:

Broccoli Planting in Iowa

Kale Planting in Iowa

Pumpkin Planting in Iowa

Any questions on growing cucumbers? Visit our forum to discuss: Gardening Forum.

Starting Soybeans Indoors

In Iowa (typically Zone 5b), begin indoor soybean seed starting between April 15 and May 15. This timeline ensures healthy seedlings ready for outdoor transplantation starting from late May to early June when the soil temperature reaches a consistent 55°F to 60°F.

Transplanting Soybean Seedlings

Transplant soybean seedlings outdoors from May 20 to June 10, ensuring the soil is warm enough for optimal germination. Space the seedlings 4-6 inches apart in rows with at least 30 inches between rows to maximize air circulation and light exposure.

General Care and Maintenance

Watering

  • Ensure consistent and thorough watering to maintain moist soil, particularly during dry spells in Iowa’s growing season.
  • Water at the base of the plants to minimize moisture on leaves, reducing the risk of fungal diseases.

Fertilizing

  • Apply a nitrogen-rich fertilizer at planting and again during the flowering stage to support healthy growth. Adding compost before planting can improve soil nutrients.

Pest and Disease Management

  • Regularly inspect for common pests such as soybean aphids and caterpillars, which can thrive in Iowa’s agricultural conditions.
  • Utilize integrated pest management strategies to protect soybean crops from pests and potential diseases like soybean rust.

Harvesting

  • Harvest soybeans when the pods are firm and the leaves have yellowed, typically in late September to early October. Timely harvesting prevents losses from over-mature seeds.

The importance of good soil

Before starting to grow it is important to take a step back and find the condition of the soil in your garden,The optimal soil is a blend that includes the mineral-rich dirt along with organicrich organic matter that plants need to thrive.


In my garden I try to compost as mutch as possible, so I can mix in the nutrient ritch compost in my soil. I use both hot composting of food scraps and cold composting of all organic garden “waste”..
If you dont have the time or space for composting, it is possible to get compost ready to use in garden centers and Community Composting.
You can read more on Community Composting here: https://www.epa.gov/sustainable-management-food/community-composting

If you are uncertain of the quality of your soil, you can get easy to use soil tests at amazon for 17 dollars. Check latest prices here: Soil testing kit.

Also remember to check out how much sunlight your growing area gets, and that the rain drains well. If you treat your soil well and plan you crops according to your climate you will succeed with any plant you want.

The satisfaction when you harvest your own produce is well worth the time you put in 🙂

BeeJay
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