What was a Garden of Simples?

Medicinal gardens, also known as herb gardens or Gardens of Simples, have been created at least since the Middle Ages, though plants were grown for medical purposes long before. A "simple" is a herb used in medical treatment.

Early medicinal gardens were created particularly in monastery courtyards. Gardens dedicated to medicinal herbs alone were quite rare in medieval times, except in these larger institutions like monasteries.  During the European Renaissance, with the advance of medical & botanical sciences, monastic herb gardens developed into botanic gardens. But the original function of these gardens was to display plants for medicinal use. The section where herbs were grown became the “Garden of Simples.”

The Garden of Simples, often referred to as a monastery’s infirmary herb garden, grew specialized plants used in medieval medicine to help the body heal itself.  Medieval medicine was based on the notion of the body having four ‘humors’ related to the 4 elements:
Blood (air) was hot & moist
Phlegm (water) was cold & moist
Yellow bile (fire) was hot & dry
Black bile (earth) was cold & dry.

It was the physician’s task to work out how to restore the balance of a person’s humors, if they became ill, & so plants & herbs were ascribed properties to redress the balance.  De Medicina (On Medicine) by the Roman author Aulus Cornelius Celsus (c 25 BC - AD 45) contained information on the use of herbs (simples) in medical practice.

De Medicina, now considered one of the finest medical classics, was largely ignored by Celsus' contemporaries. It was rediscovered by Pope Nicholas V (1397–1455) & was among the first medical works to be published (1478) after the introduction of the printing press.  The work’s encyclopedic arrangement follows the tripartite division of medicine at the time as established by Hippocrates (460-377 BC)  & Asclepiades  (124 BC - c 40 BC) - diet, pharmacology, & surgery. The historical portion of the work is of great importance; much of what is now known about Hellenistic medicine & Alexandrian anatomy & surgery comes primarily or exclusively from Celsus' De medicina. 

Celsus recommended cleanliness & urged that wounds be washed & treated with substances even now considered to be somewhat antiseptic, such as vinegar & thyme oil.  Celsus advised, for example, that "The following increase the urine: garden herbs of good odour, as parsley, rue, dill, basil, mint, hyssop, anise, coriander, cress, rocket, fennel; & besides these asparagus, capers, catmint, thyme savory, charlock, parsnip, especially growing wild, radish, skirret, onion; of game especially the hare; thin wine, pepper both round & long, mustard, wormwood, pine kernels."