Growing dianthus from seeds presents few challenges and the plants rarely suffer from transplant shock. This makes them ideal for gardeners who are starting from seed for the first time. Blooming in shades of pink, red or white, dianthus offers variety in form and size if not in colour. From simple annuals and tender perennials that grow 15 to 30 cm (6 to 12 inches) tall to frilly carnations that reach a height of 60 to 90 cm (2 to 3 feet), there's a type to suit most garden beds.
Starting dianthus plants
Fill individual pots with potting soil to within 1.25 cm (1/2 inch) of the top.
Set the pots on a tray and thoroughly moisten the potting soil with water. After a few minutes, discard any water that collects in the tray.
Place three or four seeds on top of the soil near the centre of each pot.
Sprinkle just enough soil over the seeds to cover them. Press down lightly and spray gently with water.
Stick clean twigs or craft sticks into the soil at the edge of a few of the pots and place the tray of pots inside a plastic bag. Seal the bag with a twist tie. The twigs keep the plastic from lying flat against the soil.
Place the bag of pots in a location out of direct sunlight. The seeds germinate best at temperatures around 21 degrees C (70F).
Check regularly for germination. Annual types may germinate in as few as five days, and perennials may take up to three weeks.
Remove the plastic bag once the seedlings appear, and place the tray of pots in a sunny window. A south-facing window provides the best light. Keep the soil moist but not soggy.
When the seedlings have their first true leaves, snip out the weakest plants, leaving only one in each pot.
Fertilise after 10 days with a half-strength solution of liquid houseplant fertiliser. Continue fertilising every two weeks.
Transplanting dianthus outdoors
Prepare the garden bed by loosening the soil with a garden fork, shovel or tiller to a depth of about 15 cm (6 inches).
Apply 2.5 cm (1 inch) of compost or rotted manure if your soil isn't rich in organic matter. Dianthus doesn't thrive in an organically poor soil.
Use a trowel to dig a hole as deep as the pot your seedling is growing in.
Remove the plant from the pot and place it in the hole. Fill in around the roots with garden soil and press down gently.
Water gently and keep the soil moist until the plant are established.
Wait until after the last expected spring frost to transplant most types of dianthus outdoors. Perennial pinks and carnations can take a light frost, so transplant them in early spring when the soil is cool and you may still see a light frost.
Plant dianthus in a location with well-drained soil and full sun. Provide a location with afternoon shade in hot climates.
Transplant on an overcast day or late in the evening. Alternatively, protect the plants from harsh sun for the first day or two.