With their bold palette of colors, primroses are one of spring's brightest messengers. Planted along a sidewalk or garden path, sharing a flower bed with crocus or other spring-blooming bulbs, or combined with pansies in a container, primroses will grace the landscape until other flowers take over in May. If your primroses are three or four years old and they aren't blooming as well as they have in previous years, or if the center of the plant appears to be dying, splitting the primroses can bring them back to life. Divide primroses after they finish blooming in spring, or in early autumn.
Prepare the area where you intend to plant the divided primroses. Use a shovel or a garden fork to work the soil to a depth of 6 to 8 inches, and mix in a shovelful of well-rotted manure or compost. If you live in a cool climate, plant primroses in full sun; but if you live where the summers are hot, plant them where they'll be in the shade during hot afternoons.
Dig up the primrose. Insert the shovel 5 or 6 inches away from the outer edge of the plant to avoid damaging the roots. Dig straight down, then lift the primroses carefully out of the soil.
Inspect the primrose plant. If the middle of the plant is dead, toss it on the compost heap. Divide the primrose into small chunks. As long as a chunk has a good root, it will transplant successfully.
Dig a hole for each newly-divided primrose in the prepared site. The hole should be large enough to plant the primrose with the roots spread out evenly.
Plant the divided primrose at the same soil level at which it was originally planted, and tamp the soil down lightly. Water the area well.
Spread a 1- to 2-inch layer of bark mulch or other organic mulch around the primroses to retain moisture and control weeds. Don't pile it up on the plant because that can invite insects and disease, and the buildup of heat and moisture can rot the primrose. The primroses shouldn't need to be transplanted again for two or three years.