š„¬When to Plant Kale in USDA Zone 4a (2026 Guide)
Frost actually sweetens it. Plant early spring and again for fall. Here is the cool-season planting schedule for kale in zone 4a (covering areas like northern Wisconsin, Fargo ND). All dates are based on 2026 frost data for your zone.
Start Seeds Indoors
Apr 5
Direct sow or transplant
Apr 19
Harvest From
Jun 13
Because kale is a cool-season crop, it tolerates light frost and can go out around Apr 19, before zone 4a's average last frost on May 10.
- Type: Cool-season
- Method: Direct sow or transplant
- Days to harvest: 55
- Spacing: 12" apart
- Sun: Full sun to part shade
- Zone 4a frost: May 10 ā Sep 25
- Season length: ~138 days
- Companions: beets, onion, herbs
Growing kale in zone 4a
Zone 4a has an average last spring frost around May 10 and a first fall frost around Sep 25, giving roughly 138 frost-free growing days. That window comfortably fits kale's 55-day cycle, with room for a second succession planting if you time it right.
Get a head start by sowing seeds indoors around Apr 5, roughly 5 weeks before your last frost. Move the seedlings outside around Apr 19. Give each plant about 12 inches of space in full sun to part shade.
Zone 4a specific growing notes
In zone 4a (northern Wisconsin, Fargo ND), your 138-day growing season means kale should be one of your first spring plantings. Cool-season crops thrive in the mild part of your growing window. Monitor soil temperature ā kale germinates best when soil is 40-75Ā°F.
Your first fall frost around Sep 25 means your last possible harvest is roughly late Sep. For a continuous supply, consider succession planting every 2-3 weeks from Apr 19 through mid-season.
Pro tip for kale
Frost converts starches to sugarākale harvested after a light freeze tastes noticeably sweeter. Harvest the oldest outer leaves first and the plant keeps producing from the center for months.
Troubleshooting kale
Cabbage aphids cluster in dense gray colonies inside leaf crevices and growing tips. A strong jet of water knocks most off. For persistent infestations, insecticidal soap or neem oil applied to leaf undersides works well.
Growing kale in containers
One plant per 3-gallon pot minimum. Kale is ornamental enough for mixed flower plantersāvarieties like 'Red Russian' and 'Lacinato' (dinosaur kale) look striking alongside annual flowers.
Can you plant kale twice a year?
Yesāspring and fall crops are standard practice. In zones 5+, start fall kale indoors in early July and transplant by early August. Mature kale survives winter down to zone 5 with minimal protection.
Frequently asked questions
When should I plant kale in zone 4a?
Direct sow or transplant around Apr 19. If starting from seed indoors, sow around Apr 5. Because kale is a cool-season crop, it tolerates light frost and can go out around Apr 19, before zone 4a's average last frost on May 10.
How long does kale take to grow in zone 4a?
About 55 days from sowing to first harvest. A Apr 19 planting in zone 4a is typically ready to pick from around Jun 13. Zone 4a has about 138 frost-free days ā plenty of time for a second succession planting.
How far apart should I space kale?
Space kale about 12 inches apart in full sun to part shade. This gives each plant enough room for roots to spread and leaves to catch sunlight without competing.
What is the best tip for growing kale?
Frost converts starches to sugarākale harvested after a light freeze tastes noticeably sweeter. Harvest the oldest outer leaves first and the plant keeps producing from the center for months.
What are common problems with kale and how do I fix them?
Cabbage aphids cluster in dense gray colonies inside leaf crevices and growing tips. A strong jet of water knocks most off. For persistent infestations, insecticidal soap or neem oil applied to leaf undersides works well.
Can I grow kale in a container?
One plant per 3-gallon pot minimum. Kale is ornamental enough for mixed flower plantersāvarieties like 'Red Russian' and 'Lacinato' (dinosaur kale) look striking alongside annual flowers.
Can I plant a second crop of kale for fall harvest?
Yesāspring and fall crops are standard practice. In zones 5+, start fall kale indoors in early July and transplant by early August. Mature kale survives winter down to zone 5 with minimal protection.
What grows well next to kale?
Good companion plants for kale are beets, onion, herbs. Avoid planting near warm-season crops that compete for space and nutrients. Kale also benefits from crop rotation ā do not plant it in the same spot year after year.