Pink Cottage is a variety of dianthus that has bright pink flower blooms atop tall, green, grasslike stalks. The plants are drought resistant and heat tolerant, making them a good choice for almost all gardens. Pink Cottage dianthus grows in clumps from a spreading underground root system. After the plant is 2 to 3 years of age, it must be divided into multiple plants. Pink Cottage dianthus plants that are not divided die much sooner than those which are regularly split.
Wait until the early spring to divide the Pink Cottage dianthus, as soon as the green stalks emerge from the soil and look healthy, but before the plant produces blooms.
Walk to the edge of the dianthus clump and insert the blade of a shovel straight down into the soil at the location of the outermost leaves, called the drip line. Lean back on the shovel slightly.
Remove the shovel and insert it directly next to the first location in the same manner, again leaning back to loosen the soil slightly. Continue this process to dig a trench around the entire perimeter of the portion of the Pink Cottage dianthus plant that you want to separate and replant.
Insert the shovel blade into the trench but angle it at a 45 degree angle under the dianthus plant. Lean back on the shovel handle until it almost touches the ground. Lift the roots of the plant out of the ground with the shovel or using both hands if it is easier.
Brush away as much dirt as possible from the roots so that you can see them clearly. Work your fingers into the centre of the root ball and gently pull to divide the root mass into multiple portions. If needed, use a clean, sharp knife to cut through any tough roots.
Look for new planting locations that are in full sunlight and have adequate soil drainage. Dig holes that are the same depth as the root divisions but twice as wide.
Insert the roots into the hole and backfill it, making sure the green stems are completely above the soil surface. Water the ground to a 5- or 6-inch depth and keep it moist until you see new growth develop on the Pink Cottage dianthus.