Trim tops leaving about 1 inch of stem and roots. Scrub well. Cover with boiling water and boil until skins slip easily, about 15 to 25 minutes depending on size.
Cool only enough to handle, peel, and trim stems and roots. Keep beets warm or hot. Leave baby beets whole; cut larger beets into 1/2-inch cubes or slices.
Fill jars with hot beets and fresh boiling water, leaving 1-inch headspace. Add 1 teaspoon salt per quart if desired. Adjust lids.
Pressure process pints 30 minutes or quarts 35 minutes.
Dial gauge: 11/12/13/14 psi by 2,000-ft altitude bands through 8,000 ft. Weighted gauge: 10 psi through 1,000 ft; 15 psi above.