The third object will.. Well, let's just call it "object 3". It's easier that way.
You can plant it anywhere you want. I advise some place where you don't mind spending all your time and no one else would go. Your back yard or under your cellar works if you don't have any roommates; as long as there's fertile soil. Dig at least five feet down. It won't want to be buried, but just keep piling dirt onto it (if you can still hear it when you're finished you didn't go deep enough).
Its veins (or roots, I guess) will eventually spread in all direction about a foot and a half for every year of your life. Grass and weeds will grow stiff and bony, or black and oily, or take on the colour and texture of a spider bite, or rice paper. Wood will be infected too; you'll hear the arteries in your walls pulsing on quiet nights. The ground will rot with dead insect and animal life. Don't mow your lawn; it bleeds like hell.
This is your sanctuary.
No matter what threats or injuries beset you outside, here you will be safe and healthy. Well, what passes for 'healthy' for you now. And if you really hate someone, bring them here. Trick them into coming. They'll get infected, one way or another; a lungful of spore, a thorn prick, a bit of residue on their hand. They will blood-vomit and the blood will have tiny centipedes in it. They'll shit out their own spinal fluids. Their eyes will milk over and hatch; little spines and brambles will grow from the sockets. They'll survive for months or years, doctors will be baffled.
That's all for starters. You'll learn more as you go. Much more. But if I told you everything now you might not do it.
Whatever you do, just guard it with your life, with your very soul. If you think you're in danger of losing it, dig it up, kill it with a silver needle, and let someone else make a new one someday. You'll feel as if you've pierced your own heart, but it's better than letting it fall into the wrong hands.