Asparagus is one of the few vegetables that grow wild as well as in domestic gardens. Its season is very short, lasting only three months in springtime. Asparagus begins to deteriorate as soon as it is harvested, so if you are lucky enough to have access to freshly picked asparagus in season, freezing is a simple and efficient way to have it on hand all year round.
Wash the stalks in cold, running water to remove any dirt or debris. Cut off any bruised or mushy tips or scales. Trim or break off the bottom of each stalk about 1/4 inch to 1/2 inch from the bottom. Sort the asparagus by diameter so that you are not blanching very thick stalks in the same water bath as thin ones. This will help ensure that they neither undercook nor overcook.
Fill a large pot with water, leaving enough room to avoid an overflow when you add the asparagus. Fill a large, deep bowl with water and ice. Don't pack the ice too tightly or you won't have room for the asparagus. Place the ice bath as close to the pot as you can.
Bring the pot of water to a rolling boil. Add your first batch of sorted asparagus stalks all at once. Boil the thinnest stalks for 1 minute, medium stalks for 2 minutes and thick stalks for 3 minutes.
Remove the asparagus all at once with a large slotted spoon or wire scoop -- or to make things especially easy, use a collapsible steamer to immerse and remove the stalks. Plunge the stalks directly into the ice water bath. Scoop the stalks back out after a second or two, and spread them out on paper towels or clean dishtowels to drain. Bring the water back to a boil and repeat until all of your asparagus has been blanched and shocked.
Pat your asparagus stalks with paper towels or clean dish towels until they are completely dry. This helps keep ice crystals from forming on the surface of the stalks. Place them in plastic zipper bags or resealable containers. Go ahead and fill them right to the top if you like, they don't require any head room.
Blanched asparagus will keep in your freezer for six to eight months.
Asparagus develops an unpleasant texture when it is frozen and then thawed, so it's best to prepare frozen asparagus straight from the freezer. Steam asparagus for 2 to 3 minutes depending on the thickness of the stalks, without thawing it first. Thawed asparagus works well when pureed for soup.