Good
It's fun, but I don't think your own apples should hurt you, it just makes the game less appealing.
Reviews for "Sonic Garden"
nice game
you should include instructions menu on there to
Not bad
Overall, I think this is an ok game. I don't think anyone's done something like this using Sonic before, so you get some originality points. A thing to consider would be perhaps making Sonic's hitbox a tad smaller, as I noticed often things damaged me when I didn't touch them. Also, for this type of game, power-ups are always fun. You were creativ enough to make this game, so I'm sure oyu could come up with some apple or fruit-based addition to Sonic's arsenal.
Of course this is all assuming you're going to continue to work on it. If so, additional characters would be nice too. At least Tails & Knuckles, and maybe Shadow for the hell of it. I got to wave 11 myself before I stopped paying attention, and it was good so far. It does start off a little slow, though.
As for the song, I think it fits well. SFX however, namely the sound of the apples hitting the ground, were rather annoying, at least when wearing headphones. Might want to change that particular one. Just a simple *thud* type sound suffice, I think.
As far as power-ups go, I just thuoght of a few. You could perhaps have green apples that split into pieces as you throw them, creating a shotgun-like effect. Or maybe yellow apples the explode when they hit an enemy.
All-in-all, good work so far, and keep at it