In the end, it doesn't matter who made the mansion because even if you moved in upon your arrival, that rose garden was no more than two weeks old. Because I was here one day before you and I was in that very spot on my day of arrival.

Further more, you didn't have to cover the whole rose garden. You just had to do it in the area where you would tell me to find a wilted rose.

I didn't know the type of magic you were to perform. All I knew was the wilted rose was to be a prop. Chances are almost zero that I would leave that area. The fact you said I could go anywhere in the garden lowered those chances even more. Since I was not 'limited,' I saw no need to go out of my way to look for a rose and would choose one I saw in the immediate area so I could see the trick.

I did not know what was to happen to the rose and a good many rose tricks don't require any advanced preparations. Even more reason why I wouldn't think to leave the immediate area because I didn't think there was anything done to the rose specifically before hand.

Yet another point was the magic was to be performed a bit before my departure. The chances are even smaller because I wasn't likely to go trekking over the whole garden after the second piece right before I left to find a wilted rose.

There was a possible chance I'd leave the area, but the chance was so small, it would be pure bad luck for you that I would leave the area. And everyone who performs magic has to believe they have some good luck. You even said your magic requires luck, so there's no reason to think you'd be hit by such bad luck.

And a good chunk of magic tricks is to manipulate the audience into acting how you want. All you had to do was to make sure I wouldn't have a specific desire to leave the area.