Caring for Mounding Dianthus

Site Preparation

• Mounding dianthus grows best in areas that receive at least six hours of sunlight daily. These plants also prefer well-drained, slightly sandy soil. Mixing a 1 inch layer of compost into the top 6 inches of soil before you plant helps improve drainage. Dianthus needs room to spread, so most mounding varieties are spaced 12 inches apart in all directions. This gives the plant room to form a dense mat without having to compete with nearby plants for soil moisture or nutrients.

Water and Fertilizer

• Regular watering ensures lush, healthy foliage growth and strong roots. Mounding dianthus requires about 1 inch of water weekly, which is enough to moisten the top 6 inches of soil. A light 1 to 2 inch thick mulch layer can help retain moisture, although it's usually not necessary since the mounding form of the dianthus effectively mulches itself. Watering with an all-purpose fertilizer, such as a 24-8-16 blend, every two weeks supplies sufficient nutrients. Mix 1 tablespoon of the fertilizer with a gallon of water and apply it to every 10 square feet of garden bed.

Pruning

• Deadheading removes the wilted flowers so the plants look nicer, but it can also help encourage further blooming. Simply pinch off the old flowers as soon as the petals wither, removing the swollen structure at the base of each bloom. Cutting back the entire dianthus by up to one-third of its height after each major flush of bloom encourages new, more compact growth. This results in a more evenly mounded shape and more flowers later.

Problems

• Disease rarely affects mounding dianthus if the plants are spaced correctly and if the soil drains well. Overly wet soil can cause root or stem rots, while poor air circulation in a crowded bed can lead to fungal problems. Aphids and mites may feed on the foliage. You can usually rinse these pests away with a sharp spray of water. If they continue to pose a problem, spray the affected foliage with a ready-to-use insecticidal soap spray. Reapply the spray at three to five day intervals until the pests are gone.