Preheat the grill to medium heat, 400F or 200C if you are using a gas grill.
Break or cut the woody ends of the asparagus off.
On a small sheet pan pour the olive oil over the asparagus and gently toss to coat. Sprinkle the salt, pepper, thyme, and garlic powder over the asparagus and toss again to evenly coat.
Place directly on the grill grates, close the grill and cook for 6-8 minutes. Rotate with tongs halfway through to get grill lines evenly over the asparagus.
Remove from the heat and serve on a platter. Squeeze lemon juice on top if desired.