Canning Asparagus at home is easy with the proper equipment. Because Asparagus has a low acidic content, any home canning of this vegetable will require the use of a pressure cooker. The temperature required to kill off all of the microorganisms that accumulate on the food product needs to be higher than the temperatures achieved by a boiling water bath process.
Wash the Asparagus spears and remove the tough woody portion of the stem. The easiest way to do this is to hold the spear gently with both hands...one at the tough end and the other at the top of the spear. Gently bend the stalk until it snaps. The portion that breaks off will be the toughest portion, which can either be discarded or chopped up to be dried. Save the tender top portions for the canning process.
Pack the washed, trimmed spears tightly into the sterilized, hot jars with the top of the spear pointing up and add 1 teaspoon of canning salt per quart and cover the spears with boiling water, leaving 1/4" head space. Secure the lids and screw bands onto the top of the jar and process in the pressure cooker canner. Process pints for 25 minutes and quarts for 30 minutes.
Blanch the Asparagus spears in a boiling water bath for 30 to 40 seconds. Pack the spears as hot as possible into the sterilized, hot jars and add 1 teaspoon of canning salt per quart. Always pack the Asparagus into the jars with the tough bottoms down and the tender spear tips pointed up. Pour the hot canning liquid used to blanch the spears, or, use fresh, hot boiling water into the jars, leaving 1/2" head space and secure the lids and screw bands. Process the pints for 25 minutes and the quarts for 30 minutes in a pressure cooker canner.