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Cold Frame vs Greenhouse - Which Growing Structure is Best For Your Garden?

Cold Frame vs Greenhouse: Which Growing Structure is Best For Your Garden?

For those looking to extend the gardening season or start growing early, investing in a protective structure can make all the difference. The two most common options are cold frames and greenhouses, each with pros and cons. But when deciding between them, which is the better choice for your needs? 

This guide compares these structures side-by-side, looking at critical factors like size, costs, temperature control, and maintenance. Whether a hobbyist with limited space or an experienced green thumb with big ambitions, you’ll find key information to determine if a greenhouse or cold frame is right for your situation.

Key Takeaways

  • Cold frames are small, passive structures that provide basic season extension and frost protection. Greenhouses offer larger, climate-controlled environments for all-year growing.

  • Cold frames have lower startup and operating costs compared to more expensive greenhouses.

  • Greenhouses allow for greater control of temperature, light, humidity, and airflow for optimal growing conditions.

  • Cold frames need minimal maintenance while greenhouses require regular servicing and care.

  • The choice depends on your space, budget, climate, and gardening goals. Cold frames work for basic season extension while greenhouses enable exotic plant cultivation.

a cold frame with plants inside and gardening tools in a basket

    Introducing the Cold Frame and Greenhouse Structures

    First, let’s take a quick look at what defines each of these growing structures. This will provide helpful context as we delve into the key differences between the two.

    What is a Cold Frame?

    A cold frame is a small, enclosed structure that sits directly on the ground, usually made of wood, plastic, or straw bales. It has a removable transparent top made of glass or plastic sheeting, which allows sunlight to enter. The enclosed space traps heat from the sun during the day and acts as insulation at night.

    Cold frames are typically less than 3 feet tall and range from 3-6 feet wide. They create a microclimate that can be 1-2 zones warmer inside than outside ambient temperatures. This allows gardeners to grow plants earlier in spring, and later into fall and provides some frost protection.

    Cold frames are a relatively simple, low-cost growing option often used for hardening off seedlings, giving heat-loving plants a head start, and extending the harvest of cool-weather crops like lettuce and spinach. They can be purchased pre-made, built from kits or plans, or even constructed by hand using old windows.

    What is a Greenhouse?

    A greenhouse is a much larger freestanding structure that offers gardeners greater control over growing conditions. The walls and roof consist mostly of transparent plastic or glass to let in sunlight. Greenhouses have ventilation systems, automated temperature controls, and often supplemental lighting and heating.

    Greenhouses can range dramatically in size from small backyard hobby structures to massive commercial or institutional buildings. Prices also vary widely, from $15-$50 per square foot for hobby greenhouses up to $200 per square foot for high-end commercial models.

    Greenhouses allow gardeners to effectively extend the growing season and grow plants year round that normally couldn’t survive outdoors in their climate zone. They are used to get a head start on warm weather annuals and vegetables, grow tender perennials and tropicals, and keep a fresh supply of greens through the cold winter months.

    an actual image of the Exaco Janssens Royal Victorian VI Greenhouse VI 23 surrounded by plants

    Main Differences Between Greenhouse and Cold Frame

    Comparing Size, Shape, and Structure

    When evaluating a cold frame vs a greenhouse, size is one of the first major differences that jumps out. From footprint to height, greenhouses offer a much larger growing space.

    Typical Sizes of Cold Frames vs Greenhouses

    The modest dimensions of cold frames make them a practical solution when space is limited. A typical homemade cold frame is around 3 x 6 feet and under 3 feet tall. Even commercial models meant for gardeners are usually no larger than 4 x 8 feet.

    In contrast, greenhouses can be almost any size. Small hobby greenhouses may be 8 x 12 feet, while large commercial or educational structures can sprawl over acres. Backyard greenhouses for home gardeners generally range from 100 to 500 square feet.

    Common Shapes and Designs

    Since cold frames sit directly on the ground, they are most often rectangular or square footprints. The sides are typically made of brick, stone, bales of straw, old boards, or framing.

    Greenhouses have more flexibility when it comes to shape and design. Common options are gable roofs, curved/hoop, A-frame, and geodesic dome structures. Shape can impact factors like snow load, interior growing space, and ventilation.

    Frame and Covering Materials

    When it comes to framing, cold frames usually consist of wood boards or planks since they don’t need to support much weight. The lid is often an old window sash, plexiglass, or plastic sheeting.

    Greenhouses require rigid framing, often made from metal, wood, or plastic, to handle heavy snow loads and the weight of glazing materials. Glass has excellent durability and light transmission. Rigid plastics like polycarbonate are affordable options that resist impact and fogging. Fiberglass and plastic film offer shorter lifespans but lower costs.

    an actual product image of the Exaco Janssens Junior Victorian Greenhouse standing in a garden

    Temperature Control and Growing Conditions

    One of the biggest factors when weighing a cold frame vs a greenhouse is the level of climate and temperature control each structure provides.

    Heating and Cooling Capabilities

    Cold frames are considered unheated structures, relying on passive solar heat capture during the day. Some gardeners may add a simple heat source like electrical heating cables, but there is no active climate regulation system.

    Greenhouses allow for precise control over temperatures, humidity, and airflow. Most have high-efficiency heating systems, automated vents, exhaust fans, and thermostat controllers. Cooling systems like evaporative cooling pads and shade cloths help prevent overheating in sunny months.

    Humidity and Air Flow Differences

    The enclosed space of a cold frame simply traps existing humidity and air. The only airflow regulation comes from manually propping open or removing the lid.

    In greenhouses, active ventilation and air circulation are essential. Automated vents, intake shutters, exhaust fans, and evaporative cooling pads refresh the air supply. Dehumidifiers and humidifiers maintain optimal humidity levels.

    Light Exposure in Each Structure

    When sited in a location with full southern sun exposure, a cold frame allows excellent natural light transmission through its transparent roof or lid. Shadows can be an issue at certain times in small cold frames.

    Greenhouses are designed to maximize light capture through glazed walls and roofs. Supplemental lighting like high-intensity grow lights may be used to provide adequate light in winter or for starting seeds.

    Maintenance and Cost Considerations

    Ongoing maintenance and upfront costs are two other key factors to weigh when deciding between these garden structures.

    Ongoing Maintenance Needs

    One advantage of cold frames is they have fairly minimal maintenance needs. The main tasks are venting the lid on sunny days, watering plants, removing dead plant material, and occasionally hosing down the glazing.

    Greenhouses require more significant investments of time, effort, and money to maintain optimal growing conditions. Critical maintenance tasks include cleaning glazing, checking the integrity of the structure, servicing heating and cooling systems, monitoring, adjusting, and regulating the temperature and humidity levels, and ongoing repairs.

    Initial and Operating Costs

    For hobbyists and budget-focused gardeners, one of the biggest appeals of cold frames is their relatively low cost. Handmade frames can be virtually free if you make use of salvaged windows and scrap lumber. Pre-fabricated kits typically run from $150 to $300 depending on size.

    Greenhouses have much higher initial investments, with prefab kits starting at around $1000 for very small models and professional installations costing $25-$200 per square foot. Ongoing costs for heating, cooling, lighting, and maintenance also need to be factored in.

    a live image of the Outdoor Living Today Garden in a Box With Birdnetting Cover

    Best Uses and Applications

    Deciding whether a cold frame or greenhouse is the better choice depends heavily on your specific location, space available, budget, and gardening goals. Here are some of the top uses and situations where each structure shines.

    When to Use a Cold Frame

    • Extending the shoulder seasons in spring and fall for cool weather crops
    • Hardening off seedlings over 2-4 weeks before transplanting outdoors
    • Giving frost tender perennials a head start in early spring before the last frost date
    • Growing greens and herbs into the winter months
    • Creating a warm microclimate to overwinter dormant plants like fuchsias and citrus

    When a Greenhouse is Most Useful

    • Growing warm weather annuals and veggies 2-3 months before outdoor planting
    • Raising transplants from seed over 6-8 weeks before transplanting
    • Overwintering ornamental plants not fully hardy to your zone
    • Growing tropical plants like orchids, anthurium, and palm trees
    • Maintaining living greens and fresh herbs for all-year
    • Propagating plants from cuttings or divisions

    Here is a quick rundown of the best uses for both:

    Cold Frame Best For Greenhouse Best For
    Hardening off seedlings Growing tropicals and exotics
    Cool-weather crops Raising seedlings long-term
    Basic season extension Continuous fresh produce
    Minimal frost protection Maximum climate control
    Limited space Large growing area

    Quick Comparison Overview - Cold Frame vs Greenhouse

    • Cold frames are smaller, passive solar structures. Greenhouses are larger, climate-controlled environments.

    • Cold frames have lower startup and operating costs compared to more expensive greenhouses.

    • Greenhouses allow for greater regulation of temperature, light, humidity, and airflow for optimal growing conditions.

    • Cold frames require minimal maintenance while greenhouses need regular care and servicing. Cold frames offer minimal frost protection and season extension. Greenhouses allow the ongoing cultivation of tender and exotic plants.

    a wooden cold frame with plants inside and its lid open

      Choosing the Right Structure for Your Needs - Cold Frame or Greenhouse

      When choosing a cold frame or greenhouse, the most important considerations are your:

      • Available space - Cold frames need just a few square feet while greenhouses can fill yards.

      • Budget – Cold frames are more affordable to build and operate.

      • Regional climate – Colder zones benefit more from a greenhouse’s insulation and heating.

      • Gardening goals – Cold frames help start growing plants early while greenhouses offer all-year production.

      For urban growers and small space hobbyists, a DIY or prefab cold frame is often the perfect solution for adding a month or two to your growing season. Ambitious growers with the space, budget and need for optimal growth conditions can better maximize their cultivation capabilities with a greenhouse.

      Carefully weighing the key differences between greenhouse and cold frame structures outlined here will allow you to make an informed decision based on your specific gardening needs and limitations. With the right protective growing environment in place, you can enjoy harvesting fresh homegrown produce and beautiful blooms even during the coldest winter months.

      FAQs

      How can a cold frame help protect plants in colder months?

      A cold frame creates a microclimate to retain heat and acts as insulation against frost and cold. The enclosed space and transparent lid trap solar energy during the day. This warmth allows you to grow plants earlier and extend the season into fall and winter.

      What is the main difference between a cold frame and a greenhouse? 

      The main difference is that a cold frame is a smaller, passive solar structure, while a greenhouse is a much larger, climate-controlled structure. Greenhouses allow precision control over temperature, humidity, and airflow for endless growing.

      When would I need a cold frame instead of a mini greenhouse?

      If you have limited space and budget, a cold frame can provide basic season extension and frost protection. Cold frames are best for hardening off seedlings, giving heat lovers a head start, and growing cool weather greens into winter.

      How does the glass lid of a cold frame help provide warmth for tender plants?

      The transparent glass lid allows sunlight to enter to heat up the interior. Then it acts as insulation to trap that warmth inside to protect plants. Lifting the lid provides ventilation and controls temperature.

      What are the main pros and cons of a cold frame vs a greenhouse?

      Cold frames have lower cost, minimal maintenance and provide basic protection. But greenhouses allow maximum control over growing conditions for exotic plants and vegetation all-year cultivation. Consider space, budget, and gardening goals when deciding.

      Previous article High Tunnel or Hoop House vs Greenhouse: Which Is Better for Your Garden?
      Next article Geodesic Dome Greenhouses vs Regular Greenhouses: A Detailed Comparison

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      About The Author

      Andy Wu - Resident Expert

      Andy Wu - Resident Expert

      Andy Wu is the resident backyard products expert and hails from Atlanta, Georgia. His passion for crafting outdoor retreats began in 2003.

      As a fellow homeowner, he founded Backyard Oasis to provide top-quality furnishings and equipment, collaborating with leading manufacturers.

      His main focus is on sheds and generators!

      In his spare time he like to hike the tallest mountains in the world and travel with his family.

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