Cold Frame Greenhouses

Cold Frame Greenhouses:

A Simple Way to Keep Your Garden Growing Longer

Cold Frame Greenhouses

What Exactly Is a Cold Frame Greenhouse?

• Definition: A cold frame is a low, clear box that traps heat and keeps your plants cozy even when it’s chilly outside. It’s usually built from a wooden or PVC frame and topped with a clear lid—think old windows or polycarbonate panels. The lid lets sunlight in and traps the warmth, creating a mini greenhouse effect.
• Function: Cold frames rely on passive solar energy and insulation, making them perfect for gardeners who want an easy, eco-friendly way to extend their growing seasons.

Why Use a Cold Frame?

• Extended growing seasons: Cold frames let you grow veggies earlier in the spring and later into the fall, giving you more produce throughout the year.
• Hardening seedlings: They provide a safe transition zone between indoor seed starting and outdoor planting, reducing transplant shock.
• Protection: Cold frames shield your plants from frost, wind, rain, and pests.
• Budget-friendly: Unlike full greenhouses, cold frames are inexpensive to build and maintain.

Different Types of Cold Frames and What They’re Made Of

DIY vs. pre-made:

• DIY cold frames are budget-friendly and customizable.
• Pre-made options are quicker to set up but cost more and may be less adaptable to your space.

Materials:

• Frame: Wood (like cedar), brick, PVC, or even concrete blocks.
• Lid: Recycled windows, greenhouse plastic, polycarbonate sheets, or clear acrylic panels.
• Insulation: Straw bales, foam boards, bubble wrap, or old blankets.

Portability:

• Portable cold frames are easy to move and adjust based on the sun’s angle.
• Permanent cold frames are ideal for long-term garden beds.

How to Build Your Own Cold Frame Greenhouse

Step 1: Choose the right location
Pick a spot with full sun, preferably facing south. Make sure the area drains well and isn’t prone to flooding.

Step 2: Gather your materials

• Wood, brick, or PVC for the base
• Clear cover (like old windows or polycarbonate panels)
• Hinges and handle for the lid
• Tools like drill, screws, saw, and measuring tape
• Optional: insulation material and thermometer

Step 3: Construct the frame
Build a box with the back wall slightly higher than the front to create a slope. Attach the clear lid with hinges so it can be opened for ventilation.

Step 4: Prepare the soil
Loosen and enrich the soil beneath the frame with compost.

Step 5: Monitor the environment

Use a thermometer to track temperature. Vent the lid during the day and close it at night to maintain warmth.

What to Grow in a Cold Frame

Cool-season vegetables:

• Lettuce
• Spinach
• Kale
• Arugula
• Radishes
• Carrots
• Beets
• Turnips

Seed starting in early spring:

• Tomatoes
• Peppers
• Eggplants

Winter-hardy greens:

• Swiss chard
• Mâche
• Mustard greens

Keeping Your Cold Frame in Top Shape

• Ventilation: Open the lid on warm, sunny days to prevent overheating. Use a stick or automatic opener.
• Watering: Water less frequently, as cold frames retain moisture. Always water early in the day.
• Temperature control: Ideal temps range from 55°F to 75°F during the day. Add insulation during cold nights.
• Insulation techniques: Use straw bales around the outside or bubble wrap under the lid. Cover with blankets during freezing nights.
• Soil health: Rotate crops each season, add compost regularly, and avoid overplanting the same area.

Watch Out for These Common Cold Frame Mistakes

• Overheating: Leave the lid closed too long on sunny days, and you’ll risk cooking your plants.
• Bad location: If it’s too shady or poorly drained, plants won’t thrive.
• Lack of airflow: Without ventilation, mold and mildew can build up quickly.
• Weak construction: A poorly sealed or unstable lid won’t protect against wind, animals, or rain.

Budget and Cost Considerations

DIY models:

• Use salvaged materials to keep costs low.
• Expect to spend $20–$80 depending on what you have on hand.

Pre-made units:

• Prices range from $100–$300, often with extra features.

Long-term savings: Cold frames reduce the need for grow lights, heating mats, and indoor seed-starting equipment.

Now that we have a clear understanding of the factors to consider, let’s explore some top recommendations for cold frame greenhouses that meet these criteria.

No 1: 

Wooden Garden Portable Greenhouse Cold Frame

No 2:

Wooden Cold Frame Greenhouse

No 3:

MCombo Wooden Garden Portable Greenhouse Cold Frame

No 4:

MCombo 2-Tier Wooden Cold Frame Garden Greenhouse

No 5:

Giantex Garden Portable Wooden Cold Frame Greenhouse

Conclusion

Cold frame greenhouses are one of the smartest ways to make the most of your garden all year long. They’re easy to build, affordable, and packed with benefits. Whether you’re hardening off seedlings, extending your growing season, or overwintering hardy crops, a cold frame gives you more control and more food—without complicated systems or high costs.

Key Takeaway: Using a cold frame greenhouse is a smart, cost-effective way to extend your growing season, protect your crops, and get more out of your garden—without needing electricity or a big budget.

FAQs

Can I build a cold frame without any tools?

Yes, it’s possible to use items like straw bales and an old window pane for a no-tools version, but a sturdier build will require basic tools.

Do I need to take my cold frame apart in the summer?

Not necessarily. You can either move it to a shaded spot, leave the lid open permanently, or repurpose it for pest control.

Can I use a cold frame indoors?

Cold frames are designed for outdoor use. Indoors, you’d be better off with grow lights or an indoor greenhouse setup.

What’s the best size for a cold frame?

A common size is 3 feet by 6 feet, but it depends on your available space and what you plan to grow.

Do cold frames work in very cold climates?

Yes, with added insulation like straw or foam, cold frames can help grow cold-hardy crops even in freezing temperatures.