Fill a large saucepot with about 3 inches of water. Cover, bring to a boil. Uncover, reduce heat to medium-low to a simmer. Add the asparagus. Cook for 4 minutes, stirring occasionally. Drain.
If you are grilling right away
Transfer asparagus to a plate. Season with the olive oil, salt, pepper, and garlic powder. Toss to coat. Grill over medium heat until tender, 5-8 minutes. Turning every couple minutes for an even char.
If you are making ahead
In a large bowl, add 1-quart water and 1-quart ice. Place drained asparagus into ice water to shock it. Once cold, drain again. Set aside until ready to grill. Or, the blanched asparagus can be stored in the refrigerator in an airtight container for up to one day before grilling.
Notes
A lot of people skewer their asparagus before grilling. It's not needed. Just, lay the asparagus across the grates and carefully turn them with tongs, easy!