Build a Cold Frame: Grow Through the Winter

Looking to keep your garden going even as the temperatures drop? At Donaldson’s Greenhouse, we’re here to help you take your gardening to the next level by building a cold frame. This simple structure allows you to grow fresh greens and root vegetables through the winter, making it the perfect project for ambitious gardeners. Here’s how to construct and use a cold frame to enjoy homegrown produce all season long.

What is a Cold Frame?

A cold frame is an unheated, mini-greenhouse that traps warmth and shields your plants from harsh winter conditions. It’s typically made from a wooden frame with a transparent top to let sunlight in, creating a warm, protected environment ideal for growing cold-hardy crops like lettuce, spinach, and carrots.

Materials You’ll Need:

• Wooden planks or bricks for the frame (cedar is a great choice for longevity)
• A clear cover (old windows, plexiglass, or plastic work well)
• Hinges to attach the top for easy ventilation
• Rich soil and compost for planting
• Basic tools such as a saw, hammer, and screws

How to Build a Cold Frame:

1. Pick the Perfect Spot
   Choose a sunny location with southern exposure to maximize the sunlight your cold frame will capture. Level ground is essential for stability and proper drainage.
2. Construct the Frame
   Start by building a rectangular frame to your preferred size—about 3 feet by 6 feet is common. Make the back side of the frame taller than the front to create a sloped top that helps shed water and snow.
3. Attach the Clear Cover
   Use hinges to attach a transparent cover—whether it’s glass, plexiglass, or plastic—so you can prop it open on warm days to let out excess heat and moisture.
4. Prepare the Soil
   Mix compost into your soil to ensure it’s nutrient-rich and well-draining. A layer of straw or mulch around the base of your plants can offer extra insulation on the coldest days.
5. Plant Cold-Hardy Crops
   Focus on cool-weather crops that thrive in these conditions, such as:
   • Leafy greens like spinach, kale, and arugula
   • Root vegetables like carrots, turnips, and radishes
   • Herbs like parsley and cilantro

Tips for Maintaining Your Cold Frame:

• Ventilation is Essential: Even in winter, a cold frame can get too warm on sunny days. Open the top slightly to let excess heat escape and prevent overheating your plants.
• Monitor the Temperature: Use a thermometer to track the temperature inside your cold frame. Keep it between 40°F and 65°F. For extra warmth, you can insulate your cold frame at night by covering it with blankets or lining the outside with straw bales.
• Water Moderately: Plants in cold frames need less water than during the warmer months. Keep the soil moist, but avoid overwatering.

Why Build a Cold Frame?

• Extended Harvest: A cold frame allows you to grow and harvest fresh produce well into winter, offering year-round gardening enjoyment.
• Better Flavor: Crops like carrots and spinach develop sweeter flavors when exposed to light frost.
• Sustainable Growing: A cold frame helps you grow fresh, homegrown food through the winter, reducing the need to rely on store-bought produce.

Grow Through the Winter with Donaldson’s Greenhouse

Building a cold frame is a fantastic way to challenge yourself and extend your gardening season. Donaldson’s Greenhouse has everything you need to get started, from building materials to premium cold-weather seeds. Whether you’re an experienced gardener or just looking to try something new, our team is here to help you grow through the winter.

Visit Donaldson’s Greenhouse today to chat with our experts and find all the supplies you need to build your own cold frame. Let’s keep your garden growing, even when the temperatures drop!