For many gardeners, the arrival of winter signals the end of the growing season. However, with the right tools and techniques, it’s possible to extend your harvest—and even grow fresh produce year-round. Row covers and cold frames are two of the most effective and accessible methods for protecting plants from frost, wind, and low temperatures while allowing them to thrive well beyond the traditional gardening calendar.
This article explains how to use row covers and cold frames to succeed in winter gardening, including crop selection, setup tips, and seasonal care strategies that support continuous production through even the coldest months.
Why Grow in Winter?
Winter gardening offers several benefits beyond extended harvests:
- Fresh, nutritious produce when store-bought options are limited or less flavorful
- Reduced pest pressure, as many insects are dormant
- Efficient use of space and time, especially in year-round food systems
- Lower watering needs due to reduced evaporation
- Stronger plant flavor, particularly in cool-season crops like kale, spinach, and carrots
With proper planning, even small home gardens can continue to produce well into late winter and early spring.
Understanding Season Extension Tools
What Are Row Covers?
Row covers are lightweight fabric sheets (typically made of spunbonded polyester or polypropylene) placed over garden beds to protect crops from:
- Frost and freezing temperatures
- Windburn and drying air
- Insect pests
- Excess rain or snow
They are available in various thicknesses, with lighter covers used for insect protection and heavier ones for cold-weather insulation.
What Are Cold Frames?
Cold frames are low-profile structures with a transparent top, typically made from:
- Wood or PVC frame
- Clear polycarbonate, glass, or plastic lid (hinged or removable)
They function like mini-greenhouses, trapping heat from the sun during the day and protecting plants from extreme cold at night. Some cold frames are permanent structures, while others are portable.
How Row Covers and Cold Frames Work
Both tools create microclimates that raise air and soil temperatures by a few degrees, which can make a significant difference in plant survival and growth. For example:
- A row cover can raise ambient temperatures by 2–6°F.
- A cold frame can raise temperatures by 5–10°F or more with passive solar heating.
Combined with cold-hardy crops, these tools allow you to start earlier in spring, grow longer into fall, and maintain growth through winter in many regions.
Best Crops for Winter Growing
Success in winter gardening depends heavily on selecting the right plants. Focus on cool-season vegetables that tolerate or thrive in cold temperatures.
Ideal Choices:
- Leafy Greens: Spinach, kale, arugula, Swiss chard, mache (corn salad), mustard greens
- Root Vegetables: Carrots, beets, turnips, radishes
- Alliums: Scallions, leeks, overwintering onions
- Brassicas: Cabbage, broccoli, kohlrabi, tatsoi
- Herbs: Parsley, chervil, thyme
Many of these crops improve in flavor after a frost due to increased sugar production in the leaves or roots.
How to Use Row Covers Effectively
- Install hoops or low tunnels over beds using wire, PVC, or metal conduit.
- Drape row cover fabric over the supports, securing the edges with bricks, boards, clips, or soil.
- Choose medium- or heavyweight covers (0.9–1.5 oz/yd²) for winter insulation.
- Lift the cover on warmer days to prevent overheating and allow airflow.
- Use double layering in extreme cold, with air gaps acting as additional insulation.
Row covers are lightweight and reusable for multiple seasons with proper care.
How to Build and Maintain a Cold Frame
Basic Cold Frame Design:
- Frame: Wood, bricks, or cinder blocks
- Lid: Clear acrylic, polycarbonate, or recycled windows
- Angle: South-facing slope for maximum sun exposure
Tips for Cold Frame Success:
- Vent daily when internal temperatures rise above 50°F to prevent mold and overheating
- Close lids before sunset to trap warmth overnight
- Mulch around exterior to insulate the frame
- Use water jugs or stones inside to absorb and release heat gradually
Cold frames can also be placed over raised beds or installed directly on soil for deep rooting crops.
Combining Row Covers and Cold Frames
For areas with harsh winters, combining both tools provides layered protection:
- Use row covers inside a cold frame for double insulation.
- Add floating row cover or plastic over a hoop tunnel inside a high tunnel or greenhouse.
- Layering extends the viability of tender crops well into freezing conditions.
This approach is especially useful for zone 4–6 gardeners seeking to push their growing seasons further.
Maintenance and Monitoring
- Check moisture regularly: Even in winter, plants need consistent but moderate watering.
- Watch for condensation: Vent cold frames if humidity builds up.
- Inspect for pests: Aphids, slugs, and rodents can remain active in protected spaces.
- Replace worn materials: Patch holes in row covers and clean cold frame lids for optimal light.
Proactive care keeps your plants healthy and your season-extension tools effective.
Regional Adaptations
| Hardiness Zone | Winter Gardening Strategy |
|---|---|
| Zones 7–10 | Use row covers alone or light cold frames; grow year-round easily |
| Zones 5–6 | Use cold frames or heavy row covers with cold-hardy crops |
| Zones 3–4 | Combine cold frames, mulch, and row covers; expect slower growth |
Knowing your USDA zone helps guide your winter planting schedule and tool selection.
Conclusion: Keep Growing Through the Cold
Winter gardening doesn’t require a heated greenhouse or expensive infrastructure. With simple, effective tools like row covers and cold frames, you can protect crops, extend your harvest, and enjoy fresh, homegrown produce even when snow is on the ground.
By choosing the right crops, maintaining insulation, and monitoring conditions carefully, you turn winter from a dormant period into a productive and rewarding gardening season.
Frequently Asked Questions
Can I start seeds in a cold frame during winter?
Yes, especially cold-hardy greens like spinach or arugula. For slower germination, start indoors and transplant into the cold frame.
What’s the difference between a row cover and plastic sheeting?
Row covers are breathable fabric and allow water and air through. Plastic sheeting retains more heat but requires venting to prevent overheating and condensation.
Do I need grow lights for winter gardening?
Not in cold frames or outdoor row covers, as they rely on natural light. In low-light areas, consider supplemental lighting indoors.
Can I reuse row covers every season?
Yes, if kept clean and dry. Store away from sunlight during the off-season to prevent degradation.
How cold can plants get under a row cover or cold frame?
Depending on thickness, these tools can protect plants from 4 to 10°F below ambient temperatures.