Planting Guides
When to Plant Kale in Oklahoma City: Complete Guide + Best Varieties for Zone 7a
Oklahoma City, Oklahoma
USDA Zone 7a
Last Frost: Apr 1
Last updated: October 30, 2025
Learn when to plant kale in Oklahoma City with specific dates for Zone 7a. Compare 5 varieties, get a complete timeline, and discover which kale grow best in Oklahoma.
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Quick Answer
Plant kale in Oklahoma City August 15-September 1 for fall harvest and February 15-March 15 for spring crops. Fall planting produces superior flavor when frost sweetens leaves naturally.
TL;DR
In Oklahoma City's Zone 7a climate, plant kale seeds August 15-September 1 for the best fall harvest and February 15-March 15 for spring crops. Fall planting produces superior flavor as frost sweetens the leaves, while spring crops must be harvested before summer heat triggers bolting. Brassica oleracea 'Red Russian' and Brassica oleracea 'Lacinato' are top varieties for Oklahoma's hot summers, offering better bolt resistance than curly types.
Frequently Asked Questions
When should I start kale seeds indoors in Oklahoma City?
Start kale seeds indoors 6-8 weeks before transplanting for spring crops and 4-6 weeks for fall transplants. For spring planting, start seeds indoors February 15-March 1 to transplant after the last frost around March 31. For fall crops, start seeds July 1-15 to transplant in August when temperatures begin moderating. Indoor starting gives you more control over Oklahoma's variable weather conditions.
What kale varieties grow best in Oklahoma City's hot summers?
No kale varieties truly thrive in Oklahoma City summers due to sustained temperatures above 90°F (32°C). Brassica oleracea 'Red Russian' and Brassica oleracea 'Lacinato' offer the best bolt resistance for late spring harvests before summer heat arrives. Focus on fall planting for the best results—Oklahoma's fall and winter seasons provide ideal kale growing conditions with superior flavor development.
How long can I harvest kale through Oklahoma City winters?
In Oklahoma City's Zone 7a climate, kale harvests typically continue through December and often into January during mild winters. Brassica oleracea 'Winterbor' and Brassica oleracea 'Redbor' survive temperatures down to 10°F (-12°C) with light protection. Use row covers during hard freezes below 20°F (-6°C) to extend harvests. The sweetest flavor occurs after the first frost in early November.
Why does my spring-planted kale turn bitter in Oklahoma City?
Kale turns bitter due to heat stress and premature bolting when temperatures exceed 80°F (27°C) consistently. Oklahoma's unpredictable spring weather, with March heat waves followed by temperature drops, triggers stress responses that make leaves tough and bitter. Plant heat-tolerant varieties like Brassica oleracea 'Red Russian', provide afternoon shade, and harvest frequently to prevent bolting. Fall planting produces much better flavor.
How do I protect kale from cabbage worms in Oklahoma City?
Cabbage worms cause significant damage in Oklahoma due to mild winters that allow pest populations to survive year-round. Apply Bacillus thuringiensis (Bt) spray weekly during peak butterfly activity in March-May and September-October. Use floating row covers immediately after planting to prevent egg-laying, and hand-pick caterpillars in early morning. Monitor for white butterflies starting in early March as the first generation causes the most damage.
Can I grow kale year-round in Oklahoma City?
Oklahoma City's Zone 7a climate allows two distinct growing seasons but not true year-round production. Plant August 15-September 1 for fall/winter harvest and February 15-March 15 for spring crops. Summer temperatures above 90°F (32°C) make kale cultivation impossible from June through August. Focus on maximizing the excellent October through March growing window when Oklahoma produces some of the sweetest kale possible.
What soil amendments work best for kale in Oklahoma City clay?
Oklahoma City's heavy clay soil requires significant amendment for successful kale production. Add 2-3 inches of compost and 1 inch of coarse sand to improve drainage, plus sulfur at 1 pound per 100 square feet to lower pH from Oklahoma's typical 7.5-8.0 to kale's preferred 6.0-7.0 range. Build raised beds 8-12 inches high for better drainage during spring rains. The organic matter also helps retain moisture during dry periods while preventing waterlogging.
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Written By
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Robert Foster
Robert is a retired meteorologist who turned his lifelong hobby of gardening into a second career writing about weather-climate interactions and their effects on plants. Living in Oklahoma, he's seen it all—ice storms, tornadoes, 110°F heat, and drought, sometimes in the same month. Robert brings a data-driven approach to gardening, tracking weather patterns and correlating them with plant performance in his own large garden. He's particularly knowledgeable about wind-resistant plantings, storm damage recovery, and the challenge of gardening in a climate where extremes are the norm rather than the exception. Robert is a calm, measured writer who presents information without drama.
