The Dianthus family contains more than 300 flowering plants, including the carnation and Sweet William. The flowers are known for their masses of colourful blooms that occur in the spring and summer months. Dianthus flowers are grown both commercially and in many home gardens to add colour to the landscape. Although they die back in the late summer to early fall, the barbatus, chinensis, plumarius, deltoides and superbus varieties of Dianthus are all perennials that will re-bloom the following spring.
Wait until the spring when temperatures rise above freezing. Look around the yard and find a location with well-drained soil that receives at least four to five hours of sunlight per day. Insert a pH test probe into the soil to ensure the pH is at 6.75.
Spread 1 inch of compost on top of the planting site and mix it into the soil using a garden tiller set to a depth of 6 inches.
Dig a hole in the area using a hand spade, making the hole the same width and depth as the Dianthus plant's root ball. Remove the plant from the nursery pot and insert it into the hole. Fill the hole with soil, making sure the Dianthus sits at the same level as it did in the pot.
Plant additional Dianthus varieties in the same manner, spacing each plant at 12- to 18-inch intervals.
Water the soil under the Dianthus flowers only once per week until the soil is moist to a 3- or 4-inch depth.
Apply a 10-10-10 liquid plant fertiliser to the soil once every six to eight weeks. Use the fertiliser amount specified on the bottle for the number of Dianthus plants that you have.
If your soil is too acidic, add hydrated lime in the following amounts to make it more alkaline: 113gr. per square yard in sand; 227gr. per square yard in loam; 340gr. per square yard in clay; and 709gr. per square yard in peat.
Do not spread mulch around the base of Dianthus plants.