Thank you for asking about home canning of tomatillos. A great resource is the National Center for Home Food Preservation (www.nchfp.org). Here is the information from their site:
Preserving a Harvest of Tomatillos
Elizabeth L. Andress, Ph.D. and Elaine M. D'Sa, Ph.D.
National Center for Home Food Preservation
Too many tomatillos on hand? Tomatillos may be canned by packing whole in jars and covering with hot water, for use later in the year; however, this process will cook them. You may also want to consider suggestions we have for canning them as an ingredient in salsas and relish, given below.
Quantity: An average of 14 pounds is needed per canner load of 7 quarts; an average of 9 pounds is needed per canner load of 9 pints. A bushel weighs 32 pounds and yields 14 to 16 quarts—an average of 2 pounds per quart.
Quality: Select unblemished firm, deep bright green tomatillos with a dry papery husk.
Procedure: Wash and rinse canning jars; keep hot until ready to use. Prepare lids according to manufacturer's directions. Remove the dry outer husks entirely from the tomatillos and wash the fruit well. Leave whole; do not peel or remove seeds. Add enough water to cover the tomatillos in a large saucepan and boil them gently until tender, about 5 to 10 minutes. Add bottled lemon juice or citric acid to the hot jars, according to the directions for acidification below. Fill hot tomatillos loosely into hot jars, leaving ½-inch headspace. Cover with the hot cooking liquid, leaving ½-inch headspace. Remove air bubbles and adjust headspace if needed. Wipe rims of jars with a dampened clean paper towel. Adjust lids and process.
Pint jars………………………………………40 minutes
Quart jars……………………………………45 minutes
Pint or Quart Jars………………………10 minutes
Acidification: To ensure safe acidity, add two tablespoons of bottled lemon juice or ½ teaspoon of citric acid per quart jar of tomatillos. For pints, use one tablespoon bottled lemon juice or ¼ teaspoon citric acid. Acid can be added directly to the jars before filling with product. Add sugar to offset acid taste, if desired. Four tablespoons of a 5-percent acidity vinegar per quart may be used instead of lemon juice or citric acid. However, vinegar may cause undesirable flavor changes.