Extension

Carla Smith, Pottawatomie County Horticulture Educator

Best Leafy Greens for Oklahoma:

• Spinach: Extremely cold-hardy and can tolerate freezing temperatures well into winter.
• Lettuce (Leaf type not head lettuce): Great for fall planting; harvest as "cut-and-come-again" baby greens. Tender for frost damage.
• Arugula: Fast-growing (ready in 4 to 6 weeks) with high cold tolerance.
• Kale and Collards: Thrive in cooler weather; light frosts actually make their leaves sweeter.
• Mustard and Swiss Chard: Handle chilly autumn weather and light freezes.
• Radish: typically 30 to 45 days to harvest.
• Turnips: very winter hardy, can eat both the young greens and the roots!

Planting and Timing Tips

• Timing: Sow seeds from late July through September (with spinach and leaf lettuce plantable through September) so plants establish strong root systems before severe cold arrives.
• Heat tip: Sow seeds in the shade of taller established plants like tomatoes or okra.
• Moisture Control: keep seedbeds consistently moist until sprouts emerge.

Management and Portable Protection

• Plant in a 10-12 inch pot or larger.  You don’t want the soil to dry out too fast, or to freeze solid.
• The "Wheeled" Strategy: Place your heavy containers on rolling plant caddies or dollies. This lets you effortlessly roll them into a garage, shed, or covered porch during extreme Oklahoma cold snaps (below 28°F).

• Thermal Buffering: Group your containers together tightly against a south- or west-facing brick wall. The building's radiant heat will shield your greens from freezing winds.
• Insulating the Pots: Wrap the outer bodies of your permanent outdoor containers in bubble wrap, burlap, or foam to protect the roots from freezing solid. Or ‘Double Pot’ by putting a plastic pot down into a clay pot, for better insulation.

Watering and Maintenance

• Hydration Balance: Check container soil frequently. Winter winds dry out small pots rapidly, but overwatering in winter causes root rot. Water only when the top inch of soil feels dry for established plants.  Seedlings need to be a little moist.
• Water Before a Freeze: If a hard frost is forecast, water your containers thoroughly the afternoon before. Wet soil retains heat much better than dry soil, helping protect root structures.
• Harvesting Trick: Many cold-hardy greens like kale and spinach convert starches to natural sugars during a frost, making them taste sweeter after a cold snap.
• It’s better to protect from mild dips in the weather in an unheated garage or shed, than the extreme of indoor temperatures and then back to outside.  Or simply cover with an old sheet outdoors, or a frost blanket.