Wash and rinse canning jars in a sink of hot soapy water or in the dishwasher; keep hot until ready to use.
Sterilize the mouth lids in a saucepan of hot boiling water for a few minutes. Place a few spoons on the bottom of the pan to prevent the mouth lids from touching the bottom of the pan while they boil.
Wash asparagus well, but gently, under running water. Cut stems from the bottom to leave spears with tips that fit into the canning jar with a little less than 1/2 inch headspace. Peel and wash garlic cloves. Place four garlic cloves at the bottom of each jar along with the dill seed. Tightly pack asparagus into jars with the blunt ends down then add one spicy pepper to each jar.
In a large pot, combine water, vinegar, and kosher salt. Bring to a boil. Ladle boiling hot brine over the spears, leaving ½-inch headspace.
Remove air bubbles and adjust headspace if needed. Wipe rims of jars with a clean paper towel; apply two-piece metal canning lids.
Place the jars into the canner making sure the water just covers the lids then bring to a rapid boil. Place lid on the canner and boil for 10 minutes. Remove from the canner and place on a towel lined counter to cool. You will hear a popping sound from the jars when they seal. Once they have cooled for a few hours, press your finger in the center of each lid - if it pops then it didn't seal properly. Place into the refrigerator and eat them up first (after two weeks). If they don't pop back that means they are sealed. Place the sealed jars into the pantry. Let them sit for two weeks before opening and eating. Enjoy.