Cut off beet tops, leaving 1-inch of stem and root to reduce color loss; scrub well.
In large pot, cover beets with boiling water. Boil until skins slip off easily, ≈ 15–25 minutes, depending on size.
Cool to remove skins and trim off stems and roots.
Cut beets into ½-inch cubes or slices (halve or quarter large slices); leave baby beets whole.
~ Always sterilize canning jars and lids just before using ~
Pack beets into hot jars; leave 1-inch headspace.
Add salt, if desired; ½ teaspoon for pint jars, 1 teaspoon for quart jars.
Fill jar with boiling water; remember to leave 1-inch headspace and remove any air bubbles.
Wipe jar rims and threads.
Adjust lids and begin canning.