Sanitize six wide-mouth 20-ounce canning jars in boiling water; keep hot until ready to use. Prepare lids according to manufacturer’s directions.
Rinse 10 pounds of asparagus. Cut stems so that the tipped spears fit into the jar with a little less than ½ inch headspace.
Peel six large garlic cloves and place one at the bottom of each jar. Tightly pack in the asparagus with the blunt ends facing down.
In an eight-quart Dutch oven, combine 4 ½ cups water, 4 ½ cups white distilled vinegar, hot peppers to taste, ½ cup canning salt, and three teaspoons dill seed. Bring to a boil. Pour boiling hot pickling brine over the spears, maintaining ½ inch headspace.
Remove air bubbles by gently tapping the jars against the counter; adjust headspace as needed. Wipe the jar rims with a damp paper towel; screw on two-piece metal canning lids.
Process in a boiling water canner for 10 minutes. Let cool, undisturbed, for 12 to 24 hours. Let sit for three days before eating. Unopened, the pickles keep in the fridge for two years. Once opened, consume within a month.