Common Name Dianthus, Sweet William,  
Genus  Dianthus 
Species D. barbatus, interspecific hybrids 
Family Caryophyllaceae
Life Cycle  Depends on variety - Biennial, short lived perennial, some can be grown as annuals. 
Tray Size  210
Plug Care Bump up into larger cells or harden off and transplant soon after receiving plugs. Do not expose plugs to  stressful conditions (drought stress, high heat) and do not allow to become rootbound or premature flowering may occur. 
Netting / Staking Not necessary. 
Temperature Range Hardiness zones 3-9
Spacing 10-12" 
Soil Preference Loose, fertile and well draining soil with a neutral pH is  best. For the best quality cuts avoid fertilizers with a high nitrogen content at time of flowering. Calcium uptake can be an issue in this crop - lack of calcium will show in the form of leaf tip necrosis (dead leaf tips).  Regular use of calcium nitrate will combat leaf tip necrosis. 
Day Length Long day plant - will flower early in the season when the  days are at their longest. Plant in full sun. 
Pinching Not necessary. 
When to Plant Some varieties we offer (Electron, Super Duplex, Messenger) are true biennials and need to be planted in the fall and overwintered for flowers early the next season. First year flowering varieties (Sweet, Amazon) can be planted early in the season, up to a month before last frost. They prefer the cool weather to bulk up and establish roots and will flower as warmth sets in. Protect young plants from heavy frosts by planting under cover or using agribon during freezing periods.
Harvesting Expect flowers early-mid summer, but this is dependent  on planting time (fall or spring) and weather/temperature. Harvest when 15-20% of the florets are open on an inflorescence and the rest of the buds will continue to open in the vase. 
Post Harvest Care Cut stems should immediately be placed into cool water, the use of a floral preservative will help increase vase life. Expect a vase life of up to two weeks. Can be stored in the cooler for over a week if not needed right away. 
Diseases / Insects Long periods of humidity or continuously wet foliage can cause rust or powdery mildew. Aphids are the most problematic insect with this crop - keep an eye on the vulnerable young leaves and growth tips. 
Bailey's Notes

Dianthus work well incorporated into mixed bouquets, but make an equally large impact marketed in straight bunches. 

First year flowering varieties are good candidates for  succession sowing, especially in cooler zones. Plugs  planted later in the season will bloom more quickly than  those planted in colder conditions and they will likely have shorter/thinner but still useable stems.