It is of course possible to grow a plant that prefers warmer or more humid climates in a place that does not have those things by utilizing greenhouses and other methods. You can shelter plants during the winter, etc. So at the end of the day, it depends how important the plant is to the culture in question, and what lengths they are willing to go to in order to grow it.
As Ange1e4e5 points out, the Girdle of Melian could have a mitigating effect on climate, as Melian can control what does or does not enter Doriath. It's possible that that includes cold air!
But not on natural light. One can keep tropical or subtropical plants at home nowadays also because one switches artficial light on in winter time when one comes back from work. Still it is seldom the amount of plant material necessary to support an industry.
Regarding Lorraine, there is the North Sea relatively nearby. While not an ocean it does affect the local climate. Any bigger body of waters does. And as Doriath has none nearby I would expect Doriath to be quite continental = drier in its climate.
Indigo grows in Luberon in the south of France. I never suggested it could grow in Lorraine. I was only pointing out that average nightly low temperatures in Lorraine are actually milder than in Virginia in the wintertime, despite Virginia being 10° further south.
One hectare of the plant was planted this year. A unique experiment in France that could offer new outlets for farmers in the Luberon We have a natural indigo of Provencal and French production, in organic, of very high quality and with very powerful coloring power,...
www.provence-luberon-sothebysrealty.com
Regarding the indigo article - very interesting. But is a different plant: Japanese Indigo, Persicaria Tinctori called "persicary".
https://en.wikipedia.org/wiki/Persicaria_tinctoria
Persicaria tinctoria is a species of flowering plant in the buckwheat family. Common names include Chinese indigo and Japanese indigo. It is native to Eastern Europe and Asia.
The leaves were a source of indigo dye. It was already in use in the Western Zhou period (c. 1045–771 B.C.), and was the most important blue dye in East Asia until the arrival of Indigofera from the south.
An article by Ashley Walker © copyright 2017 This year I had planned to carry out a tightly controlled experiment to look for variation in the amount of indigo produced by three fairly distinct str…
www.naturesrainbow.co.uk
The stain (rounded leaf variety
) which produces dark blue in this experment is not from the North and it does need a longer vegatation season:
"
Leena is based in Finland which has such a short growing season that the rounded leaf variety does not have time to produce seed."
One hectar and 180kg of pigment won. So still experimental phase. Will prove if it is still sustainable in 50 years. (Even if I have found a mention it is grown in other European countries successfully. No yet found out where. I know it grows feral as an escapee from flower gardens here and there but how useful that feral variety is - no idea.) Doubt any of the Doriathim would travel to Arda's equivalent of Japan to get it and come back still in one piece? (While this for sure would be quite a story!)
Natural Dyes - Indigo - Persicaria Tinctoria Persicaria Tinctoria, natural indigo powder Organic cultivation in Provence, France. A natural Indigo prepared from fresh leaves of Japanese Indigo (Polygonum tinctorium Aiton, also named Persicaria tinctoria (Aiton) Spach), manufactured in Provence...
www.theyarntree.com
INDIGO
www.vibrantvalleyfarm.com
BTW the colour on cloth seams even more faded than that of fresh unfermented woad but no idea if they fermented the persicary for up to a year or if they used it fresh:
It is again the nomencalture issue - if you mean with "indigo" any plant which contains any amount of the pigment - then woad is included and the shades do differ slightly between species. If you mean "real indigo" which produces rich dark striking shades without much effort then it is Indigofera - and that grows in the tropics and subtropics. The nearest place to get it would be probably future Harad (one of the proposed origins for Indigofera tinctoria is West Africa. The plant no longer grows wild so its exact origin is unknow.)
Still - does Doriath trade that far? Do dwarvish merchants care about trading dyes? Or even ready-made precious cloth from afar?
Who is into dye making in Beleriand? I still propose it to be humans. Those are the children of the Sun. And colours depend on sunlight. It has a reason why elves prefer grey and silver - as for them starlight is the default - the Sun is just a suboptimal fix-up for them.
And processing plants - regardles if for fiber or for pigment - is often a messy stinky process of using controlled decay, sometimes even urine, and poisoning water. Really doubt the Sindar would be into it save for some green colours which are relativelly easy to obtain.
And you metioned bilberry/ European blueberry:
how to dye fabric with blueberries •03.27.2020 04 finishThere’s not much left to do at this point but to...
laurafilas.com
This is how it does look after having been washed and dried. And this with iron mordant. And nothing about how light-fast it is - I assume it will fade even further when exposed to sunlight.
