Which came first: The grower then the greenhouse, or the greenhouse then the grower? The vast architectural wonders on show at our national botanic gardens are a beauty to behold, a statement of wealth and abundance and a result of the plant hunting mania that gripped the aristocracy with its green-fingered hunger for exotic rarities throughout the Victorian era. But the concept of a greenhouse, as an environmentally controlled place to grow plants probably dates back to the Romans. Temperature, water supply and light are the critical factors for plant growth and it is the manipulation of these to facilitate healthy plant growth that expresses our definition of a greenhouse.
The Romans, according to Pliny grew some type of cucurbits in early wheelbarrows covered in oiled cloths at night for insulation. The wheeled carts were moved outside during the day and wheeled back under cover at night.
The Italians are credited with inventing the earliest modern greenhouses to house their precious exotic plants brought back by intrepid explorers and of course Hartley Botanic have been building great greenhouses since the 1930’s, enabling growers and gardeners to elegantly and efficiently extend the season at both ends and grow fabulous flowers, fruit and vegetables.
But for me some of the most inspiring and dramatic ‘greenhouses’ I have ever seen can be found high on the plains of Peru, dating back to pre Incan times. North of the Incan capital of Cusco, 10 000 ft. above sea level at Moray, in the high Peruvian Plain are four huge earthworks, thought to be Meteorite craters that ancient Peruvian civilisations cleverly sculpted into vast, irrigated, agricultural terraces.
Across the world terracing is extensively used to grow crops at altitude, not just to make farming the slopes more practical, but because the stone walls absorb the heat of the sun during the day and then feed this warmth into the terrace soil at night to prevent them freezing. This technique is employed today in modern stone or brick wall based glasshouses, in a storage heater effect.
In Moray, drastic variations in temperature, a difference of 15C, have been measured in the 30 metres that separate the top from the bottom of these craters, creating unique microclimates that modern greenhouse growers replicate by growing under glass.
These sculpted craters facilitated ancient breeding programmes for wild vegetable species that did not grow well at altitude, such as maize – a mainstay of the Peruvian diet that was essential in the settlement of large communities in the Andes. It is possible that these massive crater greenhouses generated some of the crops on which the world depends today. The ancient civilisations of Peru contributed three thousand different potato species and around 150 different strains of Maize to agriculture; many of these are still grown by impoverished farmers across Peru. So when you start to chit your First Earlies in your winter greenhouse, spare a thought for these ancient growers that bred and selected the precursors of our modern day spuds.
Today these awesome crater ruins have been renovated to their original form in places. The existing irrigation system is partly intact and remarkably, after all this time, it is still operational, a lasting tribute to the skills and innovation of the Incan empire. Channel, aqueducts and drains redirect water from the sacred mountains above into the fertile terraces. These Incan Greenhouses, as they have become known, never flood due to the very porous rock formation beneath them. In a modern world where technology is hailed as a great miracle, perhaps we should remember the groundwork that ancient civilisations made to facilitate the comfortable existence that most in our Western society at least, enjoy.
And, given that the greenhouse effect is pretty much the reason that life exists on this planet, perhaps we should be more appreciative of our glass glazed garden creations too?