To propagate Mazus, the easiest method is by dividing established plants in early spring, just as new growth begins, using a sharp knife or spade to separate sections of the clump and replant them in a new location; you can also propagate Mazus by taking stem cuttings, but division is generally preferred due to its natural spreading habit. 

Key points about propagating Mazus:

Best time to divide: Early spring when new growth starts. 

Method: Dig up a portion of the established plant, carefully separate it into smaller sections with roots attached, and replant each section in a new spot. 

Spacing: When planting new divisions, space them 8-12 inches apart to allow for their natural spreading. 

Stem cuttings: If taking cuttings, select healthy stems, plant them in moist potting mix, and keep them in a protected area until roots develop. 

Natural propagation: Mazus naturally spreads by rooting at the nodes of its stems, so you can also simply transplant rooted offshoots from an existing plant.