Crop production in mountains?

Question

Would potato- or grain-like crops be able to flourish in northern alpine regions? There's a lot to be said about the Andeans, but the have the benefit of living near the equator that other civilizations do not

Considerations:
- 8-12 thousand feet elevation
- Steep, primarily granite mountains
- Highlands climate
- 78 to 48 F in the summers
- 45 to 15 F in the winters
- 36-40 degrees North (on an Earth map)
- late medieval technology level (but not necessarily the time period)

Answer 1

Qingke

The best analogue of your nation is actually Tibet. The Tibetan plateau sits some 4.5kms above sea level, and they have crops up there which look reasonably similar to those in lower altitudes, but with some differences.

The most common crop in Tibet is something called qingke, which is a form of barley that grows particularly well in high altitudes and is both cold and drought resistant. But, they also grow wheat, rice, potatoes and the like. If you look at their farming practices in the same link, even on the side of mountains they tend to terrace their land, putting specific crops on different terraces for the season. I'm assuming that they would rotate crops between terraces for the health of the soil but I couldn't find that information in the link.

Based on my readings, barley is a common crop for high altitude and mountainous terrains, largely because of its hardiness. BUT, it's important to note that (IIRC) it has less than a third of the energy value of wheat, meaning you need to grow more of it to get the same value in terms of energy. I don't know offhand about the nutritional values but it would appear that barley related foods are a primary staple for Tibetan farmers so it certainly has to have at least some nutritional value in that regard other than energy.

Answer 2

The Incas grew many varieties of potatoes on the Andes mountains of what is now Peru. They also grew quinoa, squash, beans, and a species of corn that is different from the modern. I would expect also that any spring crop like spinach, beets, and peas would do well in a cool environment. They used terraced gardens to compensate for the lack of flat arable ground.

Answer 3

Mind you, there's a key element beyond elevation, and that's location. Agriculture in Tibet and on the Altiplano is possible because they're close to the equator. Whereas in New England (where I'm from), treeline in the White Mountains goes under 4000 feet in areas. The alpine tundra's notoriously fragile -- footsteps can disrupt vegetation for many years -- and I wouldn't wager on cultivation to support just about any population in such a zone.

Answer 4

It depends.

You would have the fields in the valleys, not directly on the mountain sides. In the southern parts of the mountains you could grow more crops than in the northern parts. The part of the mountains where it rains a lot are worse than the sunny parts.

I found a nice article about farming in the Alps in German here: https://www.planet-wissen.de/natur/gebirge/der_mensch_in_den_alpen/pwielandwirtschaftindenalpen100.html

It is divided into the Romanesque Alps and the Germanic Alps, here are two parts translated with DeepL:

The Romanesque mountain farmer's economy

In the High Middle Ages, agriculture perfected itself in the form of the staggered economy. The alpine areas are vertically divided into different height levels, which enables the farmers to use the terraces differently throughout the year. The yields of the individual levels must be combined in such a way that a family can make a living from them. The valleys are preferably used for growing cereals, while the higher altitudes are used for grazing livestock.

Strictly speaking, Alpine agriculture must be divided into Romanesque and Germanic regions. In Romanesque mountain farming, which can be found mainly in the Southern Alps, agriculture and dairy farming are of equal importance. The farmers use the sunny areas as arable land, while the meadows are replaced by the shady locations at higher altitudes. The arable land and fertilised meadows are privately owned, the alpine pastures and the forest are there for everyone.

[...]

Germanic mountain farming

On the humid northern edge of the Alps and in the Eastern Alps, cereal cultivation is so unfavourable that livestock farming dominates in Germanic mountain farming. The landscape of the Northern Alps therefore lacks arable terraces. The farmers use the arable land only for two to three years to cultivate cereals, after which they are green again.