How to Build a Simple Cold Frame (and Why Every Garden Could Use One)

A cold frame is one of the most useful and underrated additions to any garden. It’s simple, low-cost, and incredibly effective at extending your growing season — especially if you’re working with limited space or unpredictable weather.

Think of a cold frame as a mini greenhouse: it protects plants from cold winds and frost, traps warmth from the sun, and creates a stable microclimate where seedlings and leafy greens can thrive.

Best of all? You can build one yourself using basic materials and a little time.

Or you can pick this one up online from Big W at the moment for $84.99 which I think is an excellent price (depending on quality which I can't guarantee as I don't have this particular one)

Why Build a Cold Frame?

A cold frame allows you to:

• Start seedlings earlier in the season

• Extend your harvest well into cooler months

• Protect young plants from frost and harsh weather

• Grow greens through winter in milder climates

• Make better use of small or awkward garden spaces

They’re especially helpful if you’re growing food at home and want to get more from your garden without adding complexity.

What You’ll Need

You can build a cold frame using new or recycled materials. Many people repurpose items they already have.

Basic materials include:

• Timber or recycled wood for the frame

• A clear lid (old window, polycarbonate sheet, or clear acrylic)

• Screws or brackets

• Hinges (optional, but helpful for ventilation)

• A level base or compacted soil

The beauty of a cold frame is that it doesn’t need to be perfect — function matters more than finish.

How to Build It (Simple Version)

1. Choose a sunny spotNorth-facing positions work best, especially in winter.

2. Build the frame Create a low rectangular box. The back can be slightly higher than the front to allow water to run off and capture more sun.

3. Attach the lid Secure your clear panel so it can be opened and closed easily. This allows ventilation on warm days.

4. Prepare the soil - Fill the base with quality soil or compost. Good drainage is key.

5. Plant and protect - Plant seedlings or seeds, then close the lid at night or during cooler weather.

What to Grow in a Cold Frame

Cold frames are perfect for:

• Leafy greens (lettuce, spinach, rocket)

• Herbs (parsley, coriander, chives)

• Seedlings waiting to be planted out

• +Hardy vegetables like kale or Asian greens

They’re also great for hardening off young plants before moving them into the garden.

A Few Helpful Tips

• Open the lid on warm days to prevent overheating

• Water sparingly — soil holds moisture longer in a cold frame

• Keep an eye on condensation to prevent mould

• Adjust planting based on seasonal temperatures

Why I Love Cold Frames

Cold frames are one of those simple garden tools that quietly do a lot of work. They extend the season, make growing food more accessible, and help you get more from the space you already have — without needing expensive infrastructure.

They’re especially useful if you’re short on space, short on time, or just starting out.

Want Help Setting One Up?

If you’d like help designing or building a cold frame that suits your space, I offer personalised garden planning and setup services — including advice on materials, placement, and what to grow.

You can get in touch anytime to chat about what might work best for your garden.

Happy gardening!

Kat