How to Divide Perennial Dianthus

If you're looking for a perennial border plant that blooms most of the summer, dianthus (Dianthus spp.) may be just for you. Also known as pinks, there are actually more than 300 varieties that feature blooms ranging in color from fiery red to creamy white. Make sure the plant is mature when dividing dianthus. Dianthus grow in U.S. Department of Agriculture zones 3 to 9, depending on the variety.

Perennial dianthus plants provide a blanket of color in the garden all summer long, and look good when planted in large masses. You can divide dianthus once they become mature –every three to five years is recommended.

Dianthus are fairly easy to divide. The best time for dividing dianthus is early spring, before the plants start to flower. You can divide during the growing season, but your chances of success are less. If you divide after the plants have bloomed, deadhead the blooms before transplanting. Do not transplant dianthus late in the growing season.

Good preparation will make the dividing process go smoothly. Dig a hole, at least 4 to 6 inches in diameter and at least as deep, for the dianthus cutting. You want to prepare the new location by amending the soil with compost. Transplant in the morning because the roots are better hydrated. Water your dianthus thoroughly before digging up roots.

Using a sharp spade, dig at least 6 inches under the root. Cut the root crowns of the plants you want to divide. Pry apart the crowns of the roots you've just dug up, and plant your new dianthus plants in the holes you've dug. Water the newly transplanted dianthus plants at least once a week to get your new plants established.

Dividing dianthus is not the only way to expand your dianthus flower bed. You can propagate dianthus via cuttings taken between June and September. Use garden shears or your hands to trim off a non-flowering dianthus shoot from the plant. Trim or tug the shoot just below a leaf joint.

Peel away the lower leaves and retain about four sets of leaves above the cutting. Dip the base of the cutting into hormone rooting powder. Plant each cutting 1 1/2 to 2 inches apart in a pot filled with compost, then place on a sunny windowsill. Water the pot well. After about a month, you should see roots emerge from the pots. Transplant into pots with compost, keep in a sheltered, frost-free spot, and plant in the spring.

Dianthus can spread into large mats of foliage and blooms. Dividing dianthus or propagating it helps regenerate dead spots and keeps your dianthus bed looking good each growing season. Give your dianthus the best chance of success by planting it in an area that gets at least six hours of sunlight a day.

Regular deadheading encourages dianthus to flower more vigorously throughout the growing season. Each spring, give dianthus plants a balanced, organic, all-purpose fertilizer and a bit of compost. Instead of mulch, which can cause rotting or fungus problems, use gravel to keep weeds away.

Make sure you plant dianthus in well-drained soil, as the roots won't grow well if the soil is waterlogged. Too much shade can also cause the roots to rot. When you buy dianthus, check to see if it's a true perennial dianthus variety or a biennial, which will last only two years. Look for dianthus in various colors and patterns to give your garden some interest.