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.
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.
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.
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.
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.
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.
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.
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.
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.
One of the biggest factors when weighing a cold frame vs a greenhouse is the level of climate and temperature control each structure provides.
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.
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.
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.
Ongoing maintenance and upfront costs are two other key factors to weigh when deciding between these garden structures.
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.
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.
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.
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 |
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.
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.
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.
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.
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.
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.
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.
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