What Is a Greenhouse?
When it comes to gardening, one of the biggest questions a grower can have is, "What is a greenhouse?". Originally known as botanical gardens, these structures have been used by gardeners around the world for centuries. They create ideal growing conditions for plants and protect them - especially sensitive or seasonal plants - from excessive heat or cold. If you're looking to invest in your own greenhouse garden, you might want to first understand what a greenhouse does. From there, you can learn how to best use your greenhouse with our How to use a greenhouse guide.
What is a greenhouse?
What is a greenhouse you might be wondering? Simply put, a greenhouse is a structure in which plants grow. They usually have walls and roofs and are made of mostly transparent materials (like plastic or glass) that let in light and help create a controlled climate, perfect for growing a variety of plants. Historically, greenhouses date back to Roman times, when an Armenian cucumber-loving emperor forced his gardeners to create the cultivation systems and structures on which modern greenhouses are based. Today, there are different types of greenhouses, ranging in size from small home greenhouses to large industrial structures for growing plants.
How does a greenhouse work?
Simply put, a greenhouse converts light energy into heat, which plants then use to grow. This happens in several steps:
Step 1: Greenhouse walls and roofs are usually made of large areas of translucent material such as glass or plastic. This allows sunlight to penetrate more easily and exposes the plant to natural light during the day.
Step 2: The sunlight is then absorbed by the soil, plants and everything else in the greenhouse garden, converting it into infrared energy or heat in the process.
Step 3: Once these items start to emit heat, it rises to the top, but cannot easily escape from the inside of the greenhouse due to its insulating construction. This trapped heat then begins to increase the interior temperature of the greenhouse.
Step 4: It is important to note that the insulation of the greenhouse combined with this heating process may cause the inside to be hotter than the outside. For this reason, ventilation is an extremely important part of a successful greenhouse, whether it's opening windows or doors, or using fans. Ventilation helps regulate temperature and humidity and provides air movement in your greenhouse. This fresh air supply boosts photosynthesis, plant respiration, and even allows pollinators to enter your greenhouse garden.
Step 5: Thanks to the light and heat from the greenhouse, the plants now have the right photosynthetic conditions to process the plants to grow.
Step 6: The greenhouse takes care of the heat and light, but you control the airflow, water, and fertilization of the plants. These high temperatures often lead to faster evaporation, and plants consume nutrients quickly, which means you need to water frequently and fertilize regularly.
Step 7: Depending on your intent, you can use a home greenhouse to sprout seeds, extend the growing season, propagate plants, or start growing earlier.
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Greenhouse Advantages
Greenhouses are most commonly used by home gardeners, botanists, and commercial plant breeders to control the environment in which plants grow. They provide multiple benefits such as:
Greenhouses can be used to overcome deficiencies in the environment in which plants are grown because they allow you to have more control over the climate.
These structures allow plants to grow year-round and can withstand external seasonal climate changes - especially during severe weather.
Greenhouses extend the growing season, allowing you to grow plants in late winter or early spring for transplanting when warmer weather returns.
They allow certain crops to be grown year-round, especially in marginal environments.
Greenhouses can be used for delicate processes such as seed germination.
They can even be used to grow exotic plants that may not necessarily survive outside of their natural environment.
Greenhouse Type
The wide variety of greenhouses offers gardeners plenty of options to best meet their growing needs.
Hobby: Hobby greenhouses are the perfect size for garden growers and come in all sizes and price points. These structures can be used to meet a variety of growing needs.
Lean-To: These structures are designed to lean against existing walls and potentially allow for more heat to be absorbed through the surface. When attached to a house wall, attached greenhouses often also provide the convenience of water and electricity.
Planter Racks: These vertical racks are used for growing seedlings and smaller plants in a greenhouse environment, but with a small footprint. Planters usually have plastic or vinyl enclosures with doors that roll up to give you access to plants.
Mini: Great for beginner growers, mini greenhouses are a space-saving option for growing small plants. They are usually placed above the flower bed, so no installation is required.
Cold Frames: Cold frames are often used to promote germination and rooting of seedlings in early spring. They consist of a wooden frame with glass or plastic panels that allow light to penetrate and reach the seedlings while protecting them from excessive rain or cold.
