You might be wondering how exactly you can turn regular flowers into the much cooler version in a dome. Well, the answer's simple: magic.
Once you've met the wizard and are in the "unlocking season" you can choose in the config (see the following section), you'll receive a mail from him that asks you to visit him in his tower.

Follow his invitation and you'll be treated to an event that explains the what and how and adds a new quest to your quest log. After seeing this event, all you'll have to do is re-enter his tower with a specific flower according to the season you chose. That'll trigger another event that finally rewards you with the crafting recipe for the Enchanted Crystal that you need for producing Everlasting Flowers yourself.

So, what's needed to craft the crystal? Nothing too groundbreaking (ha) if you've spent a bit of time in the mines. You'll need five solar and void essences each along with a specific gem. The gem, again, is tied to the configuration, so go read that section. Short version: You can choose from a selection of different gems!

Once you've crafted an (or multiple?) Enchanted Crystal(s), you can start producing Everlasting Flowers yourself. If you know how to use vanilla machines, you're already more than well prepared to handle the crystal. Treat them just like you'd treat kegs, though there are two exceptions: The crystal only accepts flowers as input... and it bops up and down. Processing the flower takes three days and multiplies the input flower's price by 2.5. Additionally, its quality will be preserved. All in all, this should lead to similar profit when you compare Everlasting Fairy Roses and ancient fruit wine over the course of one week.

Additionally, they make for pretty good gifts: "Generic" flowers are universally liked gifts while roses as symbols of love and friendship are loved gifts. The exception to the rule is Vincent: He dislikes them because let's be honest: What's a kid like him supposed to do with a flower inside of a dome? Additionally,  George dislikes Everlasting Dandelions while Jodi dislikes both dandelions and daffodils.

Every marriage candidate has one platonic and one romantic response when you gift them a rose while you're above eight hearts with them (again, see the config section for details) and a few villagers have unique reactions to some flowers they like or dislike, too. Can you find them all?

First things first: A config.json containing all your settings will be generated once you've started the game with the mod installed. While you can edit it with a simple text editor, I heavily recommend using Generic Mod Config Menu instead. Consequently, the following notes use the names displayed when you use it.

• Unlocking Season determines when the mail that starts the little quest chain to unlock the crystal to process flowers should be sent. Fall is set as the default for lore reasons, but if you want to unlock them sooner, sure, why not?
  

• Required Gem is a new config in the 1.6 version and lets you choose which gems should be used as part of the crafting recipe for the Enchanted Crystal. It defaults to a diamong, but if you want to start crafting them earlier, you can also choose rubies, emeralds, topaz or amethysts instead. Bonus: The resulting crystal will change its color depending on which gem you chose in the config!
  

• Relationship with [insert NPC name here] unsurprisingly determines which relationship you want to have with the respective NPC and, consequently, changes their gift reaction when you gift them an Everlasting Rose item (including ones crafted from roses from supported mods). Most people don't want every romanceable NPC to confess their everlasting love to them, so all of them are set to platonic by default. Just change them to suit your own preferences!
  

• Flower Sprites is the last category that includes all ten vanilla Everlasting Flowers. Here, you can choose which sprites you want to use for them: Vanilla, old or new Vanilla Tweaks, Better Crops and Foraging or Cuter Crops and Foraging. You can mix and match to your heart's content.