When I was a child one of my favourite books was 'The Secret Garden', but while I was told about walled kitchen gardens enclosed to keep foraging animals out I never knew walled gardens had been commonplace up until the relative recent past. From the sixteenth to the twentieth century, European urban farmers grew Mediterranean fruits and vegetables as far north as England and the Netherlands, using only renewable energy.
These crops were grown surrounded by massive 'fruit walls', which stored the heat from the sun and released it at night, creating a microclimate that could increase the temperature significantly. The 2.5 to 3 metre (9 to 10 feet) high walls were more than half a metre (20 inches) thick and coated in limestone plaster. Mats could be pulled down to insulate the fruits on very cold nights. In the central part of the gardens, crops were grown that tolerated lower temperatures, such as apples, pears, raspberries, vegetables and flowers.
The fruit wall appeared around the start of what's known as the Little Ice Age, a period of exceptional cold in Europe that lasted from about 1550 to 1850. Initially, fruit walls appeared in the gardens of the rich and powerful, such as in the palace of Versailles. However, some French regions later developed an urban farming industry based on fruit walls.
The most spectacular example was Montreuil, a suburb of Paris, where peaches were grown on a massive scale. The French quickly started to refine the technology by pruning the branches of fruit trees in such ways that they could be attached to a wooden frame on the wall.
Established during the seventeenth century, Montreuil had more than 600 km (375 miles) of fruit walls by the 1870s, when the industry reached its peak. The 300 hectare (750 acres) maze of jumbled up walls was so confusing for outsiders that the Prussian army went around Montreuil during the siege of Paris in 1870. Now there's a secret garden for you.
Peaches are native to France's Mediterranean regions, but Montreuil produced up to 17 million fruits per year, renowned for their quality. Building many fruit walls close to each other further boosted the effectiveness of the technology, because more heat was trapped and wind was kept out almost completely. Within the walled orchards, temperatures were typically 8 to 12°C (14-22°F) higher than outside.
While fruit wall gardening was certainly labour intensive I can't help but remember Mary Lennox, the sickly, foul-tempered, unsightly little orphan girl who loved no one and whom no one loved. Her discovery and care of the secret garden on her uncle's estate led not only to her transformation but to the healing of a sad family's tragedy. If all the factory work is to be done by robots, perhaps the gardens will still have need of us and treasures to share.
Near the end of the book a character says: "There must be lots of Magic in the world. But people don't know what it is like or how to make it. Perhaps the beginning is just to say nice things are going to happen, until you make them happen."
♡
ps: * The design is achieved by wrapping the fruit in a paper bag while it's growing. Once it's full size a stencil is attached to the ripening peach using egg white. The Japanese do the same with apples. :)
The illustrations of The Secret Garden were painted by Inga Moore.
