Greenhouses Are An Important Part of the British Horticultural Industry, Garden & Allotment Scene. In This Article I Explore The History Of Greenhouses, Conservatories And Orangeries.

For many years I made my living growing crops in greenhouses and polytunnels. Polytunnels are as new as plastic! But greenhouses, aka glass houses or, as the Victorians called them hot houses, have a history going back to the 17th century. Indeed, some of the heating systems adopted go back to Roman times.

In my own case I grew salads and the occasional flower crops in Dutch Light and Venlo style greenhouses. Mine weren’t high-tech “glass palaces”. They were of their day, economic but not the latest version. Indeed, some of the glass in my Dutch light houses was over 30 years old. I’ll say more about Dutch Lights later. They were a very important part of greenhouse development.

How Many Days to Maturity for greenhouse crops
Days to Maturity for greenhouse crops will vary depending on growing techniques, temperature, light, nutrition etc.

But before I write any more let’s first define a greenhouse and its use.

Clue .. it’s not one of the cheap plastic things with shelves that you can’t walk into. They have their place in gardens but aren’t what I define as a greenhouse for the purpose of this article.

What is a Greenhouse?

A greenhouse is a purpose-built structure designed to create an optimal environment for the cultivation of plants. They utilise transparent materials, primarily glass or rigid plastics scubas polycarbonate, to allow sunlight to penetrate while trapping heat within the enclosed space. This controlled environment enables gardeners, horticulturists, and commercial growers to extend the growing season, protect plants from adverse weather conditions, and cultivate a diverse range of flora that may not thrive in the native climate. In this article I’m not considering polytunnels aka hoop houses.

Key Components of a Greenhouse:

  1. Frame Structure: The framework of a greenhouse serves as its structural foundation, supporting the transparent covering and providing stability to the entire structure. Frames can be constructed from materials such as aluminium, galvanised steel, or wood, depending on the desired strength, durability, and aesthetic preferences. The Dutch light type comprised a wooden frame around the glass and this was mounted on a wooden greenhouse frame. The Venlo glasshouse has a metal frame that supports a roof ridge bar and gutters to rake the water away. But the main structure is light aluminium with he structural strength coming from the glass itself. Glass is very strong and gives the structure its strength and rigidity .. which surprises most people!
  2. Covering Material: The covering material plays a crucial role in regulating sunlight penetration and heat retention. Traditional greenhouses use glass panel, which offer durability and excellent light transmission. Alternatively, polycarbonate sheets or similar may be used but they suffer poorer light transmission and are not as strong.
  3. Ventilation System: Proper airflow is essential for maintaining optimal growing conditions within a greenhouse. Ventilation systems, including roof vents, side vents, and exhaust fans, allow for the exchange of air, preventing overheating and ensuring a balanced environment for plant growth. The smaller a greenhouse is the harder it is too control temperature and ventilation. Amateur houses are hardest to control and suffer temperature swings unknown in commercial sized structures.
  4. Heating and Cooling Systems: To regulate temperatures, greenhouses may incorporate heating systems for colder periods and cooling systems for warmer seasons. These can include radiant heating, forced-air heaters, and shade cloths to control the amount of sunlight reaching the plants. Shading is only used in very specific situations with specific crops. For example AYR (All Year Round) flower crops where day length needs controlling to get them to flower out of season.
  5. Irrigation Systems: Efficient water distribution is critical in greenhouse cultivation. Drip irrigation, misting systems, or capillary mats ensure that plants receive an adequate and consistent water supply, promoting healthy growth while minimising water wastage. I used a lot of overhead sprinkler irrigation on all sorts of crops .. the idea of watering from below often makes me smile. Try watering a crop of 100,000 lettuce from below. We used overheated sprinklers … think of them as being a bit like fire sprinklers. Done correctly no leaf ever gets burnt by the sun magnifying the sun and burning them .. that’s a myth!
  6. Environmental Monitoring: Modern greenhouses often employ sophisticated environmental monitoring systems. These systems may include sensors for temperature, humidity, light levels, and carbon dioxide concentration. Such data is invaluable for growers to make informed adjustments to maintain optimal growing conditions. Where hydroponics are used the technology also controls pH, nutrition etc. It can be very sophisticated.

Functions of a Greenhouse:

  1. Season Extension: One of the primary functions of a greenhouse is to extend the growing season beyond the limitations of the local climate. By creating a sheltered and controlled environment, gardeners can start planting earlier in the spring and continue cultivation over winter.
  2. Protection from Adverse Conditions: Greenhouses shield plants from harsh weather conditions such as frost, hail, excessive rain, or strong winds. This protection is particularly beneficial for delicate or exotic plants that may struggle to thrive outdoors in unpredictable climates.
  3. Optimal Growing Conditions: Greenhouses allow growers to tailor environmental factors such as temperature, humidity, and light to the specific needs of the plants. This precision fosters accelerated growth, increased yield, and enhanced overall plant health. Even without sophisticated controls a skilled grower can sense things like humidity levels. Growers often talk about a buoyant atmosphere being needed. Its hard to describe except to day its when its not muggy in the greenhouse. A buoyant atmosphere is a bit more than not muggy or humid, but is easy to recognise once you know it.
  4. Diverse Plant Cultivation: The controlled environment of a greenhouse allows the cultivation of a really diverse range of plants, including those that might not be native to a region. Eg. tomatoes, cucumbers, aubergines etc. From tropical flowers to subtropical fruits, greenhouses provide a versatile space for a gardener’s horticultural experimentation.

In essence, a greenhouse is not merely a shelter for plants; it is a dynamic and adaptable space where the delicate balance of nature and technology converge to provide optimal conditions for plant growth and cultivation. The evolution of greenhouse design and technology continues to shape the way we harness the power of controlled environments in our pursuit of sustainable and diverse agriculture and undoubtedly will for years. Today it is possible to grow crops such as strawberries in the UK for 12 months of the year. With it we suddenly we change crop seasonality.

Stefan Drew

Dutch Lights

Dutch Lights are so fundamental to the history of the greenhouse I’ve written a separate Dutch Light post on them. Having grown several million lettuce and over 100,000 tomato plants under Dutch Light greenhouses they have a special place in my memories

The History Of Greenhouses in the 17th Century: The Dawn of Controlled Environments

The 17th century witnessed the birth of greenhouses as we know them today. with the advent of the early plant hunters, European botanists and gardeners sought ways to protect delicate plants from the harsh external elements, enabling them to thrive in climates not naturally conducive to their growth.

history of greenhouses

One of the earliest recorded instances of a greenhouse was the “fruit room” built by French botanist Jules Charles at the Montpellier Botanical Garden in 1599. This modest structure allowed the cultivation of tropical fruits in the temperate climate of southern France. The last time I was in Montpellier the summer temperature exceeded 38C., so not so chilly, though winter temperatures are much colder.

However, it was in the 17th century that the concept of the greenhouse truly took root. The Orangery at the Palace of Versailles, constructed in 1663 under the direction of French landscape architect André Le Nôtre, became a symbol of sophistication and horticultural prowess. Designed to shelter citrus trees during the winter months, the Orangery marked a shift in gardening practices, emphasizing the controlled environment as a means of extending the growing season.

The word orangery is perhaps obvious as a place to grow oranges. But the word conservatory was also coined at around the same time. It was a place to conserve plants!

18th Century: Dutch Light Greenhouses and the Age of Exploration

The 18th century saw a surge in greenhouse innovation, notably with Dutch light greenhouses. Pioneered by Jan van der Heyden, these greenhouses incorporated large glass “windows” that allowed ample sunlight to reach the plants, fostering healthier and more robust growth. This revolutionary design became integral to the Dutch horticultural tradition, shaping the landscape of tulip cultivation and other exotic plants.

Simultaneously, the Age of Exploration fueled the demand for rare and exotic plants from distant lands. Greenhouses played a crucial role in nurturing these botanical treasures upon their arrival in Europe. The Royal Botanic Gardens at Kew, established in 1759, boasted a series of greenhouses dedicated to showcasing plant specimens collected from across the globe, affirming the greenhouse as a symbol of botanical exploration and discovery. With the first (unofficial?) director being Joseph Banks, it’s no wonder they had so many new plants requiring protection in adverse weather.

19th Century: Victorian Splendor and the Rise of Menlo

The 19th century witnessed a Victorian-era fascination with ornate and elaborate greenhouses. The Crystal Palace, constructed for the Great Exhibition of 1851 in London, exemplified the grandeur of this period. With its expansive glass structure, the Crystal Palace showcased an array of plants from various climates, captivating visitors and setting the stage for the widespread adoption of greenhouses as architectural marvels. Crystal Palace was achievable because of the progress that had been made in casting iron and making glass panes.

In the United States, the 19th century also witnessed the rise of the Menlo greenhouse. Named after the Menlo Park research facility of inventor Thomas Edison, these greenhouses were designed to harness natural light efficiently. The use of curved glass panels maximized sunlight exposure, making Menlo greenhouses a popular choice for plant enthusiasts and commercial growers alike.

20th Century: Technological Advancements and Modern Greenhouses

The 20th century ushered in a new era of technological advancements and scientific understanding, further refining greenhouse design and functionality. The introduction of automated climate control systems, ventilation, and artificial lighting allowed for precise regulation of environmental conditions, expanding the possibilities of year-round cultivation.

Dutch horticulturist L.J. van den Berg made significant contributions to greenhouse technology in the mid-20th century with the development of the “Venlo” greenhouse. This modular design, characterized by its steep roof angles and efficient use of space, became a standard for commercial greenhouse operations worldwide. Venlo houses were/are wonderful structures, I once owned a quarter acre block, that were adaptable to low growing crops such as lettuce and to vining crops such as cues and long term tomatoes that can be layered in them.

21st Century: Sustainable Practices and High-Tech Greenhouses

As we venture into the 21st century, the focus on sustainability has reshaped greenhouse practices. Greenhouse technology now integrates renewable energy sources, water-saving irrigation systems, and advanced materials to create environmentally friendly structures.

High-tech greenhouses equipped with smart sensors and computerised control systems enable growers to monitor and optimise conditions in real time. Vertical farming, a concept gaining prominence, leverages controlled-environment agriculture within urban spaces, pushing the boundaries of traditional greenhouse design. However, vertical farming is also the demise of greenhouses as no natural light is needed and glass is unnecessary. So the are building for growing in and not greenhouses.

history of greenhouses, vertical farming.

In conclusion, the history of greenhouses is a testament to humanity’s ceaseless quest for innovation in horticulture. From the modest beginnings of the 17th-century fruit rooms to the technologically advanced greenhouses of the 21st century, each era has contributed to our understanding of how controlled environments can unlock the full potential of plant growth. As we continue to cultivate a diverse array of flora within these transparent sanctuaries, the legacy of the greenhouse remains intertwined with the ever-growing story of botanical exploration and scientific curiosity.

Image Attribution: Mos.ruCC BY 4.0, via Wikimedia Commons, User:Владимир Иванов, Public domain, via Wikimedia Commons

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