When to Plant Kale in Iowa (2026 Guide)
Kale is a fantastic choice for gardeners in Iowa, as it is one of the most resilient and nutritious vegetables available. With a hardiness that allows it to thrive even in cooler temperatures, kale can be planted in both spring and fall to maximize your harvest. In Iowa's growing conditions, understanding the local frost dates is crucial for timing your planting, particularly since the median last spring frost falls around April 14 for Zone 6b and April 25 for Zone 6a.
Kale can endure hard frosts, which can actually enhance its sweetness, making it perfect for those crisp late-fall harvests. The frost-free season averages about 164 to 188 days depending on your zone, providing ample opportunity for kale to grow and flourish. Iowa's varied climate means that different cities may experience different planting windows, but the basic timing remains consistent across regions.
Whether you're in Des Moines or Cedar Rapids, ensuring your kale is planted early enough in spring or late enough in summer is the key to a successful crop. Make sure to direct sow or transplant your seedlings based on the safe date guidelines for your area. With a little planning, you can enjoy delicious and nutritious kale throughout the growing season.
Planting Schedule by USDA Zone in Iowa
| Zone | Indoor start | Transplant out | Direct sow | Harvest |
|---|---|---|---|---|
| Zone 6a | Start February 20 – March 6, ~6–8 weeks before April 25 | Transplant outdoors from April 25 – May 10, after the last frost | Direct sow from April 25 – May 15, after the last frost | Harvest from June 15 – November 30, before the first frost |
| Zone 6b | Start February 15 – March 1, ~6–8 weeks before April 14 | Transplant outdoors from April 14 – April 30, after the last frost | Direct sow from April 14 – May 1, after the last frost | Harvest from June 1 – October 19, before the first frost |
Kale Planting Windows in Iowa
- Indoor start: Indoors, start your kale seeds around February 15 for Zone 6b and February 20 for Zone 6a.
- Transplant outdoors: Transplant your kale outdoors from April 14 in Zone 6b or April 25 in Zone 6a.
- Harvest: Kale can be harvested from June 1 in Zone 6b and from June 15 in Zone 6a until approximately October 19 and November 30, respectively.
Common Mistakes Growing Kale in Iowa
- Many Iowa gardeners underestimate the plant's ability to survive frost, leading them to harvest too early. Kale's flavor is significantly improved by cold temperatures, so be patient and reap the benefits of frost-hardened leaves.
- Another common mistake is planting kale too late in the spring. Late frosts in Iowa can occur even in late April, so be sure to wait until the danger of frost has passed before transplanting your seedlings outdoors.
- Some gardeners fail to provide enough space between kale plants. Given that kale can grow to be quite large, spacing is essential to ensure good air circulation and robust growth, which helps prevent issues with mold and pests.
- Iowa's humid summers can encourage fungal diseases, so many novice gardeners overlook proper watering techniques. Avoid overhead watering and water at the soil level to keep foliage dry and minimize disease risks.
- It's crucial not to overcrowd your brassicas, including kale, by continuing to plant them in the same beds earlier than recommended. Rotating them every three years is essential to avoid diseases like clubroot that can devastate crops in Iowa's soil.
Frequently Asked Questions
What if I'm in a cold pocket of Iowa?
If you live in a colder region of Iowa, be sure to wait a little longer before planting kale outdoors. Protect your seedlings from unexpected late frosts by using row covers, and monitor local weather closely in your area.
Can I still plant kale in May?
While it's best to transplant by late April, you can still plant kale in May. Just ensure it's early in the month and be aware that it might grow slower due to potential heat stress later in the season.
When is the best time to harvest my kale?
The best time to harvest kale is from around June 1 to November 30 for Zone 6b and June 15 to November 30 for Zone 6a. The flavor improves with cold weather, so consider harvesting after light frosts for the sweetest taste.
How much space should I leave between kale plants?
Leave about 12 to 18 inches between kale plants to allow for their expansive growth. Proper spacing ensures healthy air circulation and minimizes the risk of fungal diseases common in Iowa's humid climate.
Is kale difficult to grow in Iowa?
Kale is quite easy to grow, especially for gardeners in Iowa. With its natural cold-hardiness and resilience to varying temperatures, proper soil preparation and attention to frost dates make it manageable even for beginners.
Keep Learning
City guides in Iowa
Other crops in Iowa
Typical fall sowing window for Kale in Iowa: July 29 – August 19.