The How and Why of Hot Beds @museum.de

F 2: Raised beds with, as it were, heating included were already around in the Middle Ages. Soil temperature in such a hot bed is up to 8 degrees Celsius or around 14 degrees Fahrenheit higher than in a ground-level bed. And even in medieval times, people took advantage of that. The plants grow more quickly, to a larger size, and can be harvested more often. In short: the yield is higher. It’s also important to align the hot beds properly for maximum exposure to sunlight. Hot beds are best placed lengthwise in an east-westerly direction, so the plants don’t shade each other while the sun is shining.

M 1: The posts are made of hard, durable timber, for example acacia or oak. The wickerwork, of flexible pollarded willow, is woven in between the posts. Then it's time for the filling. The bottom layer consists of branches and twigs, for example the prunings from fruit trees, which accumulate anyway. The gaps between branches are filled with soil. From about halfway up, alternate layers of soil and manure are added. As the manure rots down, the process ensures that the fill is not only especially rich in nutrients, but also generates heat.

After about 7 years, the fill of the hot bed has to be replaced, since the nutrients have been depleted. The wickerwork also has to be renewed from time to time. These days, hot beds have become very popular again – not just because plants grow so well in them, but also because the crops are easy to tend, and the beds themselves offer decorative options in garden design.

F 2: In the medieval monastery, on the other hand, the use of hot beds was mainly a way of ensuring that the canons had enough to eat. But to prevent confusion, each bed contained only a single type of plant. Only very few of the lay brothers would have been able to read.