Idea for a Short Story WIth a Farmboy Hero

The story begins with Danyil, a boy living on a farm in a remote village. The all-powerful Dark Lord sends troops into town and destroys his home, killing his family, and Danyil is only saved by a mysterious stranger who whisks him away. While Danyil trains with his growing magic powers and the blade, he learns who his real parents are. After the stranger is killed, can he rise up and defeat the Dark Lord?

Doesn't that sound great?

Yeah... I'm kidding. THIS is the real idea.

(as-yet-unnamed hero) is living on a farm dedicated to growing an herb vital to the majority of magic potions. When another country invades, they are forced to take as much of their crop as possible, burning the rest, and flee to the capital. In the most epic plot twist ever, he learns his family on the farm is... his real family! But with a squad of enemy soldiers sent to track them close on their tail, can they reach safety in time?

For a minute there I thought you were serious about the first outline, and thought, "who are you and what have you done with Merlin."

Lucky it was just a joke.

It's important that you have credible reasons that the country is being invaded and why he didn't know his family was his real family up until that point.

If you haven't thought about it, might I suggest that the other country is invading becasue they want the herbs which don't grow in their climate zone or something like that. Of course you'd need to come up with a reason that they can't trade for them. Just a suggestion.

Before you go into too much detail planning the plot, make sure you know your characters reasonably well. Otherwise you'll box in your characters personalities based on what choices they need to make for the plot's sake. This could result in unrealistic characters.

It's hard to comment much with so little to go on, but I'm sure you could pull it off. You're right in writing it as a short story. There's not enough content for a novel.

I'm thinking that the herbs are nearly impossible to plant in a new place: they have to be tended and protected from predation where they already exist, and the invading country has barely any, partly because of a rain shadow created by the mountain range along their borders.

The climatic reason is good. Fantasy often resorts to magic as an excuse for anything. "A spell was cast over the land that prevented the plants from growing" or "they don't have the magic crystal required." Those are just laziness on the author's part. The rain shadow is credible (I remember learning thesethings at school). Good idea. And remember, if it's a short story you don't have to include too much exposition, so don't worry about doing tons of worldbuilding that won't get used. Just enough to know what you're doing.

The magic in this world is different. No one throws fireballs at anyone. Instead, magic only comes in the form of potions, (for example, a potion to increase stamina or provide resistance to fire) which anyone can brew, but which must be given power by someone with the gift.

Also, I'm setting this in a world modeled after Ancient Greece. There's another story I'm writing that's set in a pseudo-Greek world too.