One tip for growing healthy dianthus perennials is to choose a location that gets full sunlight and well-drained soil for planting, since dianthus plants don't tolerate moist soil well. Another tip for successful dianthus growing is to plant in neutral to alkaline pH soil.
When growing healthy dianthus plants, it is important to prepare the soil to a depth of 12 to 15 inches using a tiller or garden fork. Mix a 2 to 4 inch layer of compost into the soil. Once the soil is prepared, dig a hole twice the diameter of the dianthus's pot. Next, remove the dianthus from its pot and place carefully into the ground so that the root ball is even with surface of the prepared soil. Pat the soil firmly down around the roots and water well. When planting multiple dianthus plants in one area, it is important to space each individual plants 6 to 12 inches apart.
After the dianthus is in the ground in the spring, add a thin layer of compost and mulch to the soil to provide the proper nutrients and moisture. Tall varieties of dianthus must be staked to grow upright. If rainfall in the area is less than one inch per week, watering is required.