Dianthus can easily be grown from seeds. For the earliest blooms, start the seeds indoors about 6 – 8 weeks before the end of frost season and plan on setting them out just before the last frost date. Use a moistened seed-starting mix in trays or pots, and press the Dianthus seeds into the soil, misting the surface to moisten the seeds. Sealing the container in a clear plastic bag is helpful in maintaining moisture. Maintain a temperature of 70°F. When sprouts are seen, remove the plastic and place the containers in a sunny, south-facing window. Water from the bottom and fertilize with water-soluble fertilizer from day 10 of seedling growth and then every 2 weeks until transplanting. Dianthus seeds for annual varieties can also be started directly outdoors in a prepared seedbed after danger of frost has passed.
Here are a few tips for growing Dianthus:
- Dianthus plants are sun lovers and need at least 6 hours of direct sun each day. If they are grown in shade, they will have few blooms and the plants will be lanky and not as compact and well-shaped.
- Deadhead the spent blooms to encourage re-blooming and prevent seeds from forming. Using Dianthus flowers for arrangements is a great way to promote new blooms, and the flowers have a long vase-life.
- Many Dianthus will self-sow. Leaving a few blooms to go to seed will make an annual seem like a perennial.
- For winter survival, lightly mulch over the roots as Dianthus plants are fairly shallow-rooted.
- Grow Dianthus in well-drained soil, and either use a slow-release fertilizer when transplanting young plants into the bed, or use a balanced liquid fertilizer each month.
- Give plants adequate spacing to allow for air movement. Remove any plant part with a sign of disease.