As a horticultural manual written in 1304 and said to have inspired Henry VIII goes on display, Hannah Stephenson investigates whether there’s any truth in its claims
I’ve heard of some strange gardening practices over the years, but some of the tips offered in a medieval gardening book which is said to have inspired Henry VIII’s lost Great Garden at Whitehall Palace take the biscuit.
The Ruralia Commoda, written in 1304, due to go on display at an exhibition at Buckingham Palace in March, claims that a squash will bear fruit after nine days if planted in the ashes of human bones and watered with oil, and that cucumbers shake at the sound of thunder.
It also mentions that lettuce loves goat manure and that combining the seeds of lettuce, radishes, nasturtium and colewort will result in a particularly tasty crop of greens.
The book, which will be displayed alongside some of the earliest and rarest surviving records of gardens and plants from the Royal Collection, entered Henry VIII’s library after the death of its owner, the King’s chaplain Richard Rawson, in 1543 and explains the importance of a king’s garden to the Tudors.
But just how much truth is there in its horticultural growing tips?
Guy Barter, head of the RHS advisory service, says: “They didn’t have squashes as we know them in those days.”
Perhaps the Latin text has been lost in translation.
“It would have been a marrow. Squashes come from North America, which hadn’t been discovered at that time. If you watered oil on the ground it would have no fertiliser effect. It might inhibit loss of moisture by evaporation but it wouldn’t control pests.
“They would have used vegetable oil as they didn’t have synthetic oil in those days and it would have been broken down in the soil. But if an old-fashioned gardener wanted to give it a go, it wouldn’t do any harm. Just don’t use engine oil!”
The manual also suggests that lettuce loves goat manure; and Barter agrees.
“Gardeners throughout history have gathered sheep manure which is an excellent quality and balanced feed, not too high in nitrogen like bird manure and probably better than cow manure. The problem is, goats are pretty thin on the ground nowadays. If you can get hold of a goat, I’m sure there’s potential there.”
Burnt human bones were obviously valued for their horticultural properties in Henry VIII’s day - and they would have added nutrients to the soil, Barter agrees.
“Mixtures of blood, fish and bones are widely sold today. Bones are a very good fertiliser. Before they had good machinery to grind up bones into bonemeal, they would have been burned and the ashes would have been rich in phosphorous and in lime. Whether human bones are better than any other bones, I wouldn’t like to say.”
While it’s not the case today, in Tudor times many soils were deficient in phosphorous. The growing of root vegetables and legumes was often inhibited by lack of phosphorous, which is needed for the healthy production of roots and good root systems.
“Plants don’t use much phosphorous but there’s desperately little of it in virgin soil, so it was lacking until the invention of the fertiliser industry in the mid-19th century,” says Barter.
He is, however, flummoxed by the claim that cucumbers shake with fear at the sound of thunder.
“I’ve never seen a cucumber shake with fear,” he laughs. “They would have been grown in cold frames covered with glass or wax. But even so, I can’t imagine why a cucumber would shake with fear. There’s a lot of thunder at RHS Garden Wisley and a lot of cucumbers and they’ve always remained rather stoic.”
However, the 14th century manual was ahead of its time in some respects, declaring that combining the seeds of lettuce, radishes, nasturtium and colewort will result in a particularly tasty crop of greens.
“Isn’t that amazing? They predicted the invention of bagged mixed salads by hundreds of years. What a brilliant idea! It’s come full circle. We used to grow everything separately and now gardeners have come back to sow these mixed salad packs and grow their own versions of the supermarket ones.
“Those plants would all grow happily in the same soil together. Radishes are a little bit hairy, but there are versions of radish that haven’t got hairy leaves so perhaps the Tudors grew those. But they would all combine well together.”
Painting Paradise: The Art of the Garden is at The Queen’s Gallery, Buckingham Palace from March 20 to October 11.