I am inordinately fond of very old gardening manuals. Most of the ones I’ve collected from second-hand bookshops and garage sales have lost their covers but not the fascination of their contents: I find there’s much wisdom in their yellowing pages, from the finer details of potato clamping to rather impressive photographs of earthing up celery (to thigh height with some dauntingly deep ditches all around. They really liked digging back then).

Plus they have really good adverts: ‘You Must Sow the best to Grow the Best’ from Unwins of Histon, Seeds of Quality; and a slightly scary advert for Corry’s Slug Death: the Magic Slug Killer which states with admirable certainty that 6,572 have been caught with one two-shilling tin. Official.

Anyway – they’re all beacons of modernity by comparison with the manual on display at the Painting Paradise exhibition at the Queen’s Gallery in London at the moment. Ruralia Commoda (literally ‘Countryside Benefits’) was written by Pietro de Crescenzi, an Italian lawyer and country landowner in 1304 and was the first printed treatise on anything to do with growing. There was no other gardening manual available at the time.

Unsurprisingly, it became a bible for 14th century gardeners. Henry VIII himself (or, I suppose, his gardeners) consulted it to create the gardens at Whitehall Palace (now lost). It’s a wonderful insight into growing techniques in an era we can only imagine; and it may have been single-handedly responsible for gardening one-upmanship by recommending that the size of a garden (20 acres, ideally) and the perfection of the plants within it were a reflection of a king’s status.

There’s been a lot of sniggering about the contents of the book: reports have concentrated on the exhortation to plant squash seeds in the ashes of human bones, and a warning that cucumbers will tremble with fear in a thunderstorm. But there are also a few tips that are food for thought even in our knowing and worldly-wise 21st century gardens.

It recommends making a turf seat between fragrant herbs, for example: eminently sensible, and advice we follow to this day when we plant perfumed roses over an arbour.

It also goes into detail about how to grow giant leeks; how to graft different coloured figs on to the same rootstock; and how to manage your soil. And there are detailed accounts of how to grow plants such as oregano, Nigella and grapevines.

Unfortunately the details are scanty – apparently the text has never been translated into English. Anyone know a good Latin speaker?