Greenhouses?

[Devor]

I'm trying to figure out how to get a greenhouse to work in medieval/magical times, and Wikipedia is just confusing me.

What are the challenges that have to be overcome to get a greenhouse working without modern technology?

 

[Ivan]

Making lots of glass, and cutting down on drafts. If you wanted to go crazy you could boil water in the greenhouse to make it more humid.

 

[myrddin173]

I don't know much about greenhouses so I would take this with a bit of salt. High production of good quality glass would probably be the only real technological requirement. Everything else I would think would be architectural, i.e. have a chamber with doors into the greenhouse proper and to the outside so air can warm up (cold air from outside then can't go directly to the greenhouse proper).

 

[topazfire]

Isn't there a greenhouse at Winterfell in Game of Thrones? He did not go into any heavy detail in the books about it, aside from mentioning that it was necessary for survival in the North. I agree with the above statements that consistant glass production would be the most technical aspect of the greenhouse to consider. If your society is magical, maybe there is a magic infused way of producing good clear glass - with magic, anything is really possible.

There was lots of glass production in the middle ages - just mostly the stained glass kind in Cathedrals.

 

[Devor]

Doing a little more research, it looks like the issues are the glass, ventilation, heating, blocking off the wind, and irrigation.

At a glance, "float glass" is a modern technique, where the molten glass floats over molten tin to even out the chemicals. I have no idea why that would work, but I don't see why it couldn't be done in premodern times.

Ventilation is easy enough, as fans can be powered by animals, and animals will provide manure that can be burned for fuel to boil water for heating. Wind can be blocked with hedges. And irrigation in this world is a problem I've already figured out.

So . . . it shouldn't really be a problem to have greenhouses? Are there other difficulties?

 

[Caged Maiden]

The size of it would probably be a factor. Modern greenhouses are made of plastic... and can be huge. Technically, the theory of a greenhouse is just to give plants plenty of light, and a consistent temperature, water, and rich soil. I don't think it is at all outside the realm of possibilities. In one of my novels, I used an elaborately planned bath house to pipe water to a lush garden, you could use both the heat and water and humidity of old bath houses and simply turn that into your greenhouse plan. Another suggestion would be I believe from Peru, where the Incas used irrigation canals to extend the growing season high up in the mountains.....

I think the question would be... "If someone wanted it in Medieval times, could they have built it?" and the answer would be yes. "Was it worth the expense?" probably not to them... but very much to you. I say maybe think a little outside the box and make some substitutions so it isn't completely a nineteenth century invention placed in another time period (unless you like that idea).

A note about manure.... certain plants need certain nutrients, and I accidentally killed my Raspberry bushes with steer manure. And I can't imagine the smell of moist manure in an enclosed area. I'd rethink the poop if anything.

 

[Devor]

In one of my novels, I used an elaborately planned bath house to pipe water to a lush garden, you could use both the heat and water and humidity of old bath houses and simply turn that into your greenhouse plan.

That's brilliant! I'm so using it. The bath houses are the heating system for the greenhouses. I love it.

A note about manure.... certain plants need certain nutrients, and I accidentally killed my Raspberry bushes with steer manure. And I can't imagine the smell of moist manure in an enclosed area. I'd rethink the poop if anything.

It's a weird ecosystem. I'm using Tibet as the very basic model for the ecosystem, and manure is very often the only fuel available in Tibet - hence the need for greenhouses.

That said, the actual society is nothing like Tibet. If the manure is burned to boil water to make a bath and heat the greenhouse, I think it would be easy to separate the actual fire and its smell from baths and the steam. I'm not going to worry about it.

((edit)) And I forgot. Believe it or not, Yak poop has no smell.

 

[Caged Maiden]

That said, the actual society is nothing like Tibet. If the manure is burned to boil water to make a bath and heat the greenhouse, I think it would be easy to separate the actual fire and its smell from baths and the steam. I'm not going to worry about it.

((edit)) And I forgot. Believe it or not, Yak poop has no smell.

ooooooh I thought it was the soil for the plants... which I wouldn't recommend in anything more than small amounts. I'm glad I could help.

 

[Saigonnus]

Greenhouses have been around since the roman empire in some form or another, so it would be perfectly reasonable to have them in any fantasy novel. You may not even need to use heating, depending on the climate and on the building materials present. If it is like Tibet, you could use water from a natural hot spring to heat the inside of the greenhouse, limiting the need for plumbing.

 

[Ivan]

The above is much better than using precious fuel to boil water and heat the air just for plants. I don't know the socio-economic structure of your world but if greenhouses are run by free small-holding farmers, you could set up a contrast between scrabbling out an existence on yak poop versus luxuriating in the vapors of a hot spring.

 

[Devor]

If it is like Tibet, you could use water from a natural hot spring to heat the inside of the greenhouse, limiting the need for plumbing.

For various reasons, a hot spring would not be possible. Springs happen when the water pressing down in a mountain pushes up in a valley, and in this setting the landscape has been altered so that it would never happen naturally.

They do it artificially, however, with qanats and plumbing for their water.

The above is much better than using precious fuel to boil water and heat the air just for plants.

It's not when you need those plants to survive.

 

[Saigonnus]

You may not even necessarily need to use water in general aside from the obvious need for irrigation... if you craft the greenhouse from dark stone and windows it will absorb heat and radiate it into the covered area, also the windows would allow heat to get in, in the form of sunlight, so humidity; depending on the climate and the crop may not be a necessity and a limited amount could be made via evaporation. Perhaps the only time you'd need to heat the inside of the greenhouse is at night, limiting the amount of fuel you'd need to use.

Also, I thought I would mention that many types of Lichen or Moss will grow in a climate like Tibet and are easily usable as fuel as well; Maybe they mix it with the yak patties and compress it, so it takes longer to burn. Processing it with other types of green waste (most of which is flammable when dried) could be a way to stretch out their limited supply of excrement. I do something similar to that in my WIP, the Druids tend to use everything from plants and animals that they can.

 

[SeverinR]

For glass production, would it be only rich people able to afford the glass to make a greenhouse?
I guess I always assumed glass was expensive in the middle ages.

As for fertilizer, wouldn't using a potting soil be better? Mix the excrement with dirt, so as not to shock the plants with direct contact? Also the smell would be lessened. I think proper treatment of excrement, sun dried to kill parasites and germs, which also makes the smell less noticable. But then again, if you have a good way to dry it, you probably wouldn't need to have a greenhouse (except maybe in winter).
Also human excrement was a common fertilizer. I beleive meat eaters produce stronger smelling feces then herbavores, also herbavores eat more fiber, which makes it alot easier to handle. I know I'd rather walk around in a dirty horse stall then step in one dog pile.

 

[Devor]

For glass production, would it be only rich people able to afford the glass to make a greenhouse?
I guess I always assumed glass was expensive in the middle ages.

As for fertilizer...

So far as the glass is concerned, the greenhouses would be part of a system of infrastructure needed for a community to prosper, rather than privately owned. So I'm not worried about the costs.

I'm also not very concerned with fertilizer, I just want the feel of seeing or walking through the place.

 

[Caged Maiden]

It sounds like you are well on your way Devor. I wonder whether you need a lot of glass or only a small amount. Mostly what plants need is water. If you can put them into an environment where they get adequate light during the day, for instance if the doors were all opened or the plants otherwise exposed during sunlight hours, and then the building closed up at night to keep them warm... well that ought to work just fine. I can't imagine these people would be growing tropical flowers up at that altitude, they are probably more concerned with food-bearing plants, and many like peppers take a small amount of soil and only adequate light and water. You could probably avoid glass altogether and merely provide shelter for the plants at night when because of the altitude, the temperature plummets. Ha, yeah I live in Albuquerque, and the growing season here is just as short as up north because of our altitude. However, if you plant in raised beds it is extended weeks, and several plants (like onions, lettuce, herbs, and peas) survive throughout the winter as long as it doesn't stay below 20 degrees farenheit for too many days. In fact, we had quite a cold winter this year, and all of my onions, lettuce, oregano, sage and chives are still green and I could have cut them all winter. (They were somewhat mulched by the fallen leaves). Just some things to consider. There are many cold-hardy plants you could take advantage of and minimize the need for EVERYTHING to be grown indoors if it isn't your vision to do so.