The Roman Emperor Tiberius has had a pretty bad press these last two thousand years. Even if you don’t believe everything you read in Robert Graves’ I CLAUDIUS, you can’t ignore the ancient writers who were Graves’ source material. They tell how Tiberius committed every type of crime and indulged in every sort of perversion. He murdered anyone who displeased him, sexually abused children…oh yes, and neglected the government of his Empire. Well, he was an absolute ruler and, as Lord Acton remarked, “All power corrupts. Absolute power corrupts absolutely.”
Modern historians, though, are asking how many of these dire reports are actually true, and how much was exaggerated or even invented by writers who were hostile to Tiberius or his family. That’s another story, and not for today. Because I’ve come across at least one good thing that Tiberius is credited with. His gardeners invented the greenhouse.
The Romans were enthusiastic gardeners, and grew a wide range of plants, especially vegetables, that we still cultivate today. Tiberius, it seems, was very partial to cucumbers, and insisted on having fresh ones for his table all year round. Even in a Mediterranean climate this posed a challenge to his gardeners in winter-time, and with the added problem of working for a master who had a short temper and powers of life and death…not surprisingly, they found a way to deliver what he wanted.
They used to grow their cucumbers in large carts that could be wheeled outdoors in sunny weather and brought inside again at night or when it was cold. Not a complete answer, because long cold spells might mean the plants were kept indoors for days on end and would fail from lack of light. So the gardeners covered the carts with translucent panes that let in light but kept out the worst of the chills, and the plants could be outdoors even in cold weather.
The covers were made of selenite, a form of gypsum which was soft enough to be easily cut into very thin sheets, yet hard enough to serve as quite large panes. Why not use glass? They didn’t have the technology to make large clear panes of glass; they did manage small opaque glass windows for richer folks’ houses, but these were expensive and perhaps more fragile than the mineral sheets. Whatever the reason, the selenite covers proved a good practical solution.
Mind you, not all Roman gardeners’ ideas about cucumbers was so sensible. They believed that soaking the seed in milk, or in honeyed wine, would make the resulting fruits extra tender. Harmless enough, but how about this? They advised that women shouldn’t be allowed anywhere near the cucumber beds, as sturdy plants’ growth would be stunted. And if a woman was having her period, one writer claimed that “just her look will kill immature young ones.” What a load of…er…manure! Probably an excuse by frightened gardeners whose plants weren’t flourishing. “Sorry, master, but the mistress came by yesterday and since then…”
Never mind, the covered-cart idea was passed on by several ancient writers on gardening as a workable technique. I suppose the cucumber-houses were more cold frames than true greenhouses, but they were a start. So next time you tuck into a mixed salad or toy with a thin cucumber sandwich, spare a thought for Tiberius and his gardeners, laying the foundations for a new technique.