Nothing is more satisfying than enjoying fresh, homegrown vegetables all year long. Imagine biting into a juicy, homegrown tomato in the middle of winter or harvesting fresh greens when everything outside is covered in frost. Sounds like a dream, right? But that can seem like a fantasy if you live in an area with cold winters or short growing seasons.
However, with the help of greenhouses, you can transform your garden into an oasis of greens, herbs, and more, even when snow is falling outside. A greenhouse allows you to create a warm, sheltered environment where you can get an early start on seeds in the spring and protect delicate plants from frost. It captures and retains heat from the sun, protecting fragile plants from harsh weather changes and early frosts.
Whether you’re a home gardener that wants to enjoy fresh veggies all year or a commercial grower who wants to boost your production, a greenhouse can extend your garden season by weeks or even months. This can increase the variety and quantity of food you can produce year-round if you’re in a place where outdoor gardens have a very short season. Soon, you’ll be harvesting salad fixings and garnishes weeks or even months before the local store.
In this guide, we will explore the different types of greenhouse structures based on your climate and other ways to extend your growing season. Let’s get started with choosing a greenhouse that’s perfect for you.
Types of Greenhouses for Extending Growing Seasons
Cold Frame Greenhouses
One of the simplest and most affordable ways to extend your growing season is to install a cold frame greenhouse. Unlike other structures, cold frames are placed directly on the ground without a foundation.
They have a basic structure made of wood, metal, or plastic topped with a clear lid, often glass or polycarbonate. This makes them inexpensive to build and highly portable. You can easily move them to follow sun patterns or store them for winter. Cold frames are especially great for gardeners who aren’t ready to invest in a full-scale greenhouse but still want the benefits of extending their growing season.
The idea behind it is straightforward: it traps sunlight and creates a warmer microclimate for your plants. This allows you to get a jump start on the growing season or extend it well into the colder months.
During the day, sunlight passes through the transparent top, heating the air and soil inside. The heat gets trapped, keeping everything nice and warm. At night, the cold frame provides just enough insulation to keep frost at bay, which is why it’s perfect for early spring or late fall gardening.
Since cold frames are not fully enclosed or insulated, they provide less climate control than permanent greenhouses. However, they are perfect for getting a head start on spring planting or protecting vulnerable plants through fall.
Heated Greenhouses
If you live in very cold climates, a heated greenhouse is an even more productive option than a cold frame. Although the initial costs might be higher, a heated structure allows you to cultivate warm-weather crops and seedlings practically all year by simply regulating the temperatures.
These greenhouses create a consistently warm environment using heating systems that keep your plants cozy and thriving, regardless of how harsh the weather is outside. Regular greenhouses rely on the sun to warm them up, but heated greenhouses take it up by adding external heat sources. These heat sources can be anything from electric heaters, propane or gas systems, or even solar-powered heating units.
The heat from lighting is another creative and affordable passive method. Many experienced greenhouse gardeners hang supplemental grow lights and simply turn them on at night to provide warmth when it’s cold. Then, on sunny days, good ventilation protects delicate plants from getting scorched.
The great thing about heated greenhouses is that you get a certain level of control. You’re not just at the mercy of the weather. You can set and maintain specific temperatures depending on what you’re growing. Many systems even come with thermostats that automatically adjust the heat, so if there’s a sudden cold rush at night, the heater kicks in and keeps your plants from freezing.
Hoophouse or High Tunnel Greenhouses
A hoop house or high tunnel greenhouse is a very popular and affordable option for many farmers and serious gardeners. This simple but effective structure allows gardeners to extend their growing seasons without the complexity or high costs of more permanent setups. As the name suggests, these structures have round arches of piping or wood bent into hoops to create a strong frame.
Hoophouses are a great choice if you have more space but want something temporary. They use UV-treated plastic sheeting instead of glass for the top covering, secured along the sides. This makes it easy to install and dismantle at the end of each season.
During the day, sunlight passes through the plastic covering and heats the air and soil inside the tunnel. This trapped warmth creates a microclimate that’s warmer than the outside temperature. At night, the plastic covering provides enough insulation to keep frost from creeping in, allowing you to start planting earlier in the spring and keep crops growing later into the fall or even winter. It’s like wrapping your garden in a protective blanket.
Because hoop houses have such large interiors, they provide plenty of room for growing vegetables, berries, and other plants on a larger scale than smaller garden greenhouses.
Geodesic Dome Greenhouses
A geodesic dome greenhouse is an architectural marvel. It is a unique type of freestanding greenhouse with a distinct spherical shape. Based on geodesic geometry, dome frames are made of triangular sections of piping or wood connected to form a strong, self-supporting structure that requires no internal supports.
The greenhouse’s dome shape distributes weight evenly and provides strength, making it a good choice for withstanding extreme weather conditions like heavy snow, strong winds, and even hailstorms.
The magic of the geodesic structure is in how it can maximize sunlight effectively. Thanks to the curved surface, sunlight hits the dome at different angles throughout the day, ensuring an even distribution of light inside the greenhouse. This means your plants get more consistent sunlight from sunrise to sunset, which is important for year-round growth.
The shape of the dome also helps create natural airflow. This regulates the temperature and reduces the need for artificial heating or cooling. Warm air naturally rises to the top of the dome, while cooler air settles at the bottom, which helps maintain a stable climate in the greenhouse.
Additionally, geodesic dome greenhouses have more growing area compared to other types of greenhouses because of their unique shape. This is especially useful for vertical gardening, as the dome provides enough headroom for tall plants or trellised crops like tomatoes, cucumbers, and beans.
Techniques for Using Greenhouses to Extend Growing Seasons
Temperature Control
Temperature control helps to keep your plants growing long after the traditional growing season has ended. Plants are picky. If the temperature is too cold, they’ll stunt or wither. If it’s too hot, they’ll wilt or burn. So, in order to extend your growing season, you must keep the internal climate just right, no matter what’s going on outside.
During Warmer Months
First, you must understand that a greenhouse traps heat through the greenhouse effect, where sunlight enters through the transparent walls and roof, warming the air and soil. However, if you’ve ever walked into a greenhouse on a hot summer day, you know that this heat can quickly build up.
Hence, ventilation is important to prevent overheating. During warm months or sunny days, proper airflow keeps the temperature stable and prevents your greenhouse from cooking your plants.
Most greenhouses come with roof vents or side vents that you can open to let in fresh air and release excess heat. Some people even install automatic vent openers that react to the rising temperature. Fans can also help circulate the air inside, ensuring no hot spots develop.
During Colder Months
When the colder months roll in, you have to keep your plants warm. Insulation becomes your best friend during these times. To trap more heat, you can use double layers of plastic or install bubble wrap on the inside walls of the greenhouse.
If you want a more high-tech setup, you can also use polycarbonate glazing. This not only helps with insulation but also improves light diffusion, ensuring your plants get enough sunlight without being scorched.
You can also use electric heaters to provide consistent warmth and keep the internal temperature from dropping too low overnight or during cold spells. If you want a more eco-friendly approach, you can use solar panels to power your heating systems. Take advantage of sunny days to store energy for cooler nights.
Light Management
Plants need light to survive and grow. And without adequate light, their growth will slow or stop entirely. In a greenhouse, it’s very important to manage light because you’re controlling an environment that’s designed to be enclosed.
This means you’ll need to ensure your plants get enough light during shorter days while protecting them from too much sun during hotter months. If you can achieve this balance, you can extend your growing season and grow healthy plants all year round.
During the colder months, you’ll want to maximize the amount of natural light your greenhouse receives. You can do this by keeping the greenhouse cover clean and clear of any dirt, dust, or debris that could block sunlight.
You can also use materials like polycarbonate glazing on the roof and walls to ensure that the sunlight is spread evenly across the greenhouse. This will help you extend your growing season into winter.
If you live in an area with short winter days or regions where natural light alone is insufficient, you should use supplemental lighting. You can install grow lights to extend the daylight hours your plants receive. This mimics the long summer days they need. LED grow lights are popular because they’re energy-efficient and long-lasting, and you can tailor them to provide the specific light spectrum that your plants need.
However, light management isn’t just about increasing the amount of light; sometimes, it’s about reducing it. In summer, when there’s a lot of sunlight and temperatures are high, too much light can actually harm your plants. You can use shade cloths or install retractable shades to control how much direct sunlight enters your greenhouse.
Soil Management
If you don’t properly manage your soil, all the warmth and light in the world won’t mean much. You need healthy soil to grow strong, resilient plants that can thrive all year in your greenhouse.
Your greenhouse plants need a well-balanced mix of soil to flourish, especially if they’re growing outside their typical seasons. The ideal soil is loose, well-draining, and rich in nutrients. However, soil in greenhouses can easily become compacted over time, mostly if you’re growing continuously. If this happens, regularly aerate the soil with a garden fork or gently till it to keep it loose and ensure the roots can spread freely.
Greenhouses provide a controlled environment, but they can also dry out soil faster than outdoor gardens due to the higher internal temperatures and limited rainfall. You must consistently water the soil to prevent it from becoming too dry or too waterlogged. Keep an eye on the moisture levels and adjust your watering schedule based on the season to keep your plants happy and roots healthy.
In cold climates or during the winter months, you need the soil to be warm in order to extend your growing season. Plants slow down or even stop growing when the soil is too cold. To avoid this, you can use heating cables or thermal mats beneath your plants to keep the soil warm and encourage continued growth.
Moisture Control
Moisture control is often one of the tricky aspects to extending your growing season. Too much water can lead to soggy soil, root rot, and diseases, while too little can dry out plants, stunt growth, and weaken their ability to thrive in less-than-ideal temperatures.
The most basic step in moisture control is consistent watering. In a greenhouse, you’re in charge of rainfall, which means you have to mimic what your plants need depending on their growth stage, season, and the climate inside your greenhouse.
One great option for precise watering is a drip irrigation system. This system slowly delivers water directly to the roots, preventing overwatering and ensuring that each plant gets exactly what it needs.
You can also pair the system with a soil moisture sensor to help gauge the moisture level in the soil and adjust watering accordingly.
Humidity control is just as important as managing moisture in your greenhouse. Greenhouses often trap moisture, leading to high humidity levels, which can promote the growth of mold and mildew and even attract pests. If you’re not careful, this can become a breeding ground for diseases that attack your plant.
So, consider installing fans or vents that regulate airflow and humidity. You can also use dehumidifiers if the moisture level in the air gets too high, especially during winter or rainy periods. During hot, dry weather, you can use simple methods like placing water trays or misting the air to help increase moisture and maintain a humid environment.
Conclusion
Extending your growing season with a greenhouse is easy if you can implement all we’ve discussed here. It isn’t just about getting a few extra weeks out of your plants; you also have to create a controlled environment that lets you grow all year, regardless of what nature throws your way.
You don’t even need to be a professional grower to make it work. You just need a little knowledge (which we’ve provided) and a willingness to experiment. So, why limit your harvest to just a few months when you can enjoy fresh, homegrown produce or vibrant flowers no matter what season it is with a greenhouse?
