A How-To Guide on Building a Cold Frame

One captivating way to enhance a garden’s allure is by constructing a small greenhouse. And perhaps you find yourself hesitating, unsure if investing is the right thing to do. Such uncertainties can be a stumbling block for many aspiring greenhouse enthusiasts.

So we’re here to help! In this guide, we will guide you through the process of building a cold frame, in particular. Keep reading to get started!

What Is a Cold Frame?

DIY cold frame using wood and corrugated plastic, featuring space beneath that helps protect the contents from frost while also providing a handy storage space for plant pots.

(Image Credit: Flickr)

A cold frame is a simple and small gardening structure used to extend the growing season for plants. It especially comes in handy during colder climates, hence the name. It consists of a low, transparent enclosure set on a sturdy frame. Common materials used are glass, polycarbonate, and plastic. Placed outdoors, a cold frame captures and retains sunlight and warmth. It creates a microclimate that protects plants from frost and adverse weather conditions.

Cold frames are versatile and serve multiple purposes. Among their many objectives is starting seedlings earlier in the spring. They provide a sheltered environment for tender plants. Moreover, nurture cool-season crops during the winter. They are positioned on the ground for easy access for planting, care, and harvesting.

With good ventilation and temperature management, cold frames can function as standard greenhouses. But what sets them apart is their inexpensive way to extend the growing season.

Materials Needed

Before constructing your cold frame, gather all the necessary materials. Having the right components at hand will ensure a smooth building process. Here’s what you’ll need:

Materials for the frame:

  • Wood (e.g., cedar or pine)
  • Transparent covering (glass or clear plastic)
  • Screws or hinges

Sourcing options:

  • Recycled materials (old windows, reclaimed wood)
  • Purchasing new from hardware stores
  • Alternative options (polycarbonate panels)

Tools required:

  • Saw
  • Drill
  • Screwdriver
  • Measuring tape

With these materials and tools, you’ll be well-equipped to start building your cold frame.

Planning Your Cold Frame

DIY cold frame featuring recycled windows with potted peppers inside

(Image Credit: Flickr)

A well-planned cold frame is key to successful gardening. This stage focuses on the steps crucial for creating an effective cold frame:

Deciding the size and location

The size of your cold frame should match your gardening needs. Consider the space available and the quantity of plants you intend to grow. Location is equally important. Choose a spot shielded from strong winds but accessible for regular maintenance. Also, keep in mind the area’s exposure to sunlight throughout the day and across seasons.

Orientation of maximum sunlight

Orient your cold frame to maximise exposure to sunlight. A south-facing direction is usually ideal in the Northern Hemisphere. This ensures plants receive ample light throughout the day.

Now, suppose you live in a region with intense sun. Slight angling or shading might be necessary to prevent overheating. Tilt the cold frame lid towards the sun, ideally at a 30-45 degree angle. Or use a light cloth or shade netting over the frame during the peak sunlight hours.

Considerations for drainage and ventilation

Good drainage is crucial. Ensure the site has natural drainage or incorporate a drainage system in your design. Ventilation is equally important for temperature and humidity control. Go for adjustable vents or openings that can be opened or closed based on the weather.

Step-by-Step Construction Guide

Wooden cold frame with window covers slightly opened, showing the plants inside.

(Image Credit: Flickr)

Here’s a straightforward guide to constructing your own cold frame, step by step:

Step 1: Building the frame

  • Measure and cut your wood to create a rectangular frame. A standard size is 3 feet by 6 feet, but this can be adjusted based on your needs.
  • Assemble the frame using screws, ensuring all corners are square for stability.
  • Tip for durability: Treat the wood with a weather-resistant sealant. Doing so will add protection against moisture and decay.

Step 2: Adding the lid

  • Attach hinges to one side of the frame, allowing the lid to open and close easily.
  • Fix the glass or plastic covering to the lid using screws. Ensure it’s securely fastened and watertight.
  • Safety tip: When handling glass, wear gloves and safety glasses to prevent injuries.

Step 3: Ventilation and insulation

  • Create ventilation openings on the sides or top. These can be adjustable for better temperature control.
  • Insulate your cold frame by adding weather stripping around the lid. This helps retain heat during colder months.

Using Your Cold Frame

Now that your cold frame is ready, it’s time to learn how to use it effectively to boost your gardening. Here are key tips for planting, maintenance, and seasonal use:

When and how to plant in the cold frame

  • Begin planting in early spring or late winter for season extension.
  • Ideal plants for a cold frame include hardy greens and seedlings.
  • Plant directly into the soil in the frame, or place pots inside.

Daily maintenance tips

  • Monitor and adjust the lid position daily to regulate temperature. Open it on warm days to prevent overheating, and close it on cold nights.
  • Water the plants as needed, ensuring the soil remains moist but not waterlogged.

Seasonal usage and storage advice

  • Use the cold frame in spring and autumn for growing and protecting plants.
  • In summer, remove or prop open the lid to prevent overheating.
  • During winter, clear snow from the lid and check for insulation gaps.
  • If not in use, clean and store the frame in a dry place to prolong its life.


Building and utilising a cold frame is a fantastic way to extend your gardening season. Not only that but also to protect delicate plants and enhance plant growth. All without breaking the bank! With this guide, you have the knowledge and steps to construct and maintain your own cold frame.

Remember, the key to success lies in careful planning, proper construction, and regular maintenance. Embrace this project, and soon, you’ll enjoy the fruits of your labour with a thriving garden all year round.

For a larger gardening solution, explore our range of greenhouses for sale. At Garden Buildings Direct, we cater to all your gardening essentials. Make sure to check out potting sheds to enhance your extended cultivation experience!

Up next on your reading list: How to Build Your Own Mini Greenhouse

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In spring, in a small greenhouse, you can grow plug plants and plant cucumber seeds. In summer, grow Mediterranean crops like aubergines, tomatoes, and peppers. In autumn and winter, use your small greenhouse to overwinter delicate plants. You can continue growing leafy salads.

Where energy from the sun is re-absorbed and trapped after reflecting off the Earth’s surface. This, in turn, increases the temperature of Earth, much like the inside of a greenhouse.

We tend to think a wood-polycarbonate hybrid gives you the best structure, insulation, and sunlight. If you want, check out our list of the best greenhouses. 

As we’ve shown in this guide, you can build a cold frame or mini-greenhouse out of things lying around the garden. But if you want something you can move around and grow in year-round, you’ll need a full-sized greenhouse.

For example, our BillyOh Lincoln polycarbonate greenhouse starts at £425.

A gable greenhouse has an apex roof that connects to the upright walls. This is in contrast to a curved greenhouse design.

It depends on what you intend to use it for. If it’s for a hobby, then one of the biggest disadvantages - that it needs a lot of care, might turn out to be an advantage!

Further costs may be incurred depending on whether you want to heat your greenhouse or not. But this is all personal preference. The benefits of gardening and harvesting crops, we believe, far outweigh any negatives.

We suggest starting with low maintenance plants like salads, lettuces, and leafy greens. Or, you could look at easy-to-grow and hardy plants. Think courgettes, sugar snap peas, and even squashes.