Companion Planting for Winter Crops: Plants That Grow Well Together Under Tunnels or Cold Frames

ByStephen Albert

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Companion planting is a valuable technique for winter gardening, helping crops grow stronger, resist pests, and maximize space. From my experience growing vegetables in Iowa’s Zone 5 winters to year-round winter gardening in Sonoma, pairing compatible crops under tunnels or cold frames improves yields and overall plant health.

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Here’s how to plan companion planting for winter crops.

1. Benefits of Companion Planting in Winter

  • Improves growth: Some plants enhance nutrient uptake or provide shade for others
  • Reduces pests: Certain plants repel insects or confuse pests
  • Optimizes space: Mix tall, slow-growing crops with low, fast-growing crops
  • Enhances soil health: Nitrogen-fixing plants enrich the soil for neighboring crops

My Experience:
In Iowa, I grew kale with spinach under low tunnels. The taller kale provided slight shade for the spinach, preventing bolting during early winter sun. In Sonoma, I mix lettuce and arugula under cold frames for continuous harvest and pest reduction.

2. Winter-Friendly Companion Pairs

Leafy Greens

  • Spinach + Lettuce: Fast-growing greens that share space and thrive under tunnels
  • Kale + Swiss Chard: Kale shades chard seedlings, extending harvest

Root Crops

  • Carrots + Radishes: Radishes mature quickly, loosening soil for slower-growing carrots
  • Beets + Lettuce: Lettuce grows in between beet rows, using space efficiently

Nitrogen-Fixers

  • Peas + Brassicas: Peas enrich the soil, benefiting kale, cabbage, and broccoli

Herbs for Pest Control

  • Parsley + Spinach or Lettuce: Attracts beneficial insects
  • Cilantro + Leafy Greens: Deters aphids and other pests

Tip:
Avoid planting heavy feeders like broccoli and kale together; they compete for nutrients under confined tunnel space.

3. Using Companion Planting in Tunnels and Cold Frames

  • Stack crops by height: Tall crops on the north side to avoid shading smaller plants
  • Mix fast and slow growers: Harvest quick-growing crops before slower ones mature
  • Consider microclimates: Plants needing slightly more warmth go in the center of tunnels
  • Rotate annually: Reduces soil-borne diseases and maintains soil fertility

My Experience:
In Iowa, I staggered radishes and carrots in mounds under row covers. The radishes acted as a natural “soil loosener” for carrots, while the cover protected both from frost.

4. Tips for Success

  • Keep companion plantings small and manageable under winter protection
  • Observe plant interactions—some pairs thrive, others may compete
  • Use succession planting to rotate crops in companion beds for continuous production
  • Combine companion planting with thermal mass, mulch, and frost protection to optimize winter growth

Key Takeaways

  1. Companion planting enhances growth, reduces pests, and maximizes space in winter gardens.
  2. Pair leafy greens, root crops, nitrogen-fixers, and pest-deterring herbs wisely.
  3. Use height, growth rate, and microclimate to organize plants under tunnels or cold frames.
  4. Rotate and succession plant for ongoing productivity.
  5. Observation and adjustment ensure companion planting works effectively in any winter garden.

Using companion planting, your winter garden becomes more productive, resilient, and space-efficient, whether in harsh Iowa winters or mild Sonoma conditions.

Stephen Albert is a horticulturist, master gardener, and certified nurseryman who has taught at the University of California for more than 25 years. He holds graduate degrees from the University of California and the University of Iowa. His books include Vegetable Garden Grower’s Guide, Vegetable Garden Almanac & Planner, Tomato Grower’s Answer Book, and Kitchen Garden Grower’s Guide. His Vegetable Garden Grower’s Masterclass is available online. Harvesttotable.com has more than 10 million visitors each year.

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