When to Plant Dianthus: Spring Planting, Seed Starting and Sweet William Timing for Pinks and Carnations

Dianthus is a big genus: NC State counts over 27,000 registered cultivar names, and the Almanac says there are over 300 species. They are grown as annuals, biennials and evergreen perennials (NC State). The garden groups are perennial pinks such as Cheddar pinks (D. gratianopolitanus) and cottage pinks (D. plumarius), China pinks (D. chinensis), sweet William (D. barbatus) and carnations (D. caryophyllus) (Almanac). NC State says the name "pinks" refers to the frilled petal edges, as if cut with pinking shears, not to the color.

When to plant dianthus

Use our planting calendar to find your frost dates. The Henderson County Master Gardeners add that cold-treated sweet William bought in spring flowers the same year, and that many newer cultivars bloom in their first year if started early from seed.

How to plant dianthus

The RHS adds organic matter rather than grit to heavy soil and waters well after planting. The Almanac transplants seedlings once they have four sets of leaves, after hardening them off.

Watering, feeding and deadheading

• Water only when dry. The Almanac waters when the soil dries out; the RHS says plants in the ground need water only in a long drought.
• Keep mulch off the stems, which invites crown rot (Almanac).
• Feed lightly, if at all. The sources differ: the RHS says plants in the ground are unlikely to need feeding but containers do, while the Almanac feeds a few times a season with a balanced fertilizer.
• Deadhead for more flowers. The RHS cuts back to the next bud, and NC State deadheads Cheddar pinks for later blooms. The Almanac shears plants after flowering in late summer for a second flush.
• Stake carnations (RHS).

Dianthus in containers

The RHS suggests containers when garden soil stays wet and says potted plants do need feeding, unlike those in the ground. Compact pinks such as Cheddar pinks, 6 to 12 inches tall (NC State), suit pots and edges. Our reading is to use a pot with drainage holes, a free-draining mix and an empty saucer, since winter wet is the main risk (RHS).

Fall and winter

• Worry about wet, not cold. The RHS says dianthus are fully hardy and are more likely to be damaged by winter wet; NC State says Cheddar pinks do not tolerate wet winter soil.
• Refresh old plants. The RHS says some pinks are short-lived or go bare in the middle, so take cuttings every 2 to 3 years; the Almanac divides on the same schedule.
• Let sweet William reseed if you want it every year; the Henderson County Master Gardeners say it self-seeds, though doubles don't come true from seed.

Pests and problems

NC State says poor drainage and poor air circulation lead to root rot, and lists crown rot and rust for sweet William, with slugs and snails in shade. The Almanac adds aphids, grasshoppers, sow bugs, botrytis, leaf spot, rust and aster yellows. NC State and the Almanac both call dianthus deer resistant, but NC State says rabbits eat it. NC State also notes the leaves can cause mild stomach upset or skin irritation if handled or eaten and flags the genus as a concern for dogs, cats and horses, so think about where pets graze.

Dianthus in the vegetable garden

Low pinks make a tidy, sunny edging for a vegetable bed, and sweet William and carnations are classic cut flowers; the Almanac says cut stems last 7 to 21 days, and the Henderson County Master Gardeners say sweet William lasts about 2 weeks in a vase. They pair with other cool-season and cottage flowers such as snapdragons, sweet alyssum, pansies and lavender (our reading, based on their shared need for sun and drainage). See also flowers that attract beneficial insects. Scabiosa also likes sun and neutral to alkaline soil; see when to plant scabiosa.

Frequently asked questions

When is the best time to plant dianthus?

Most are best planted in spring, or in summer if kept moist (RHS). The Almanac also plants nursery plants in the cool months of fall.

When should I start dianthus seeds?

Indoors 10 to 12 weeks before the last frost, or outdoors in early spring while a light frost is still possible. Cover seed lightly, since it needs light (Almanac).

When do I plant sweet William?

It is a biennial, so sow it in summer for flowers the next year: July in Britain (RHS), or 6 to 8 weeks before the first frost (University of Arkansas). Cold-treated plants bought in spring bloom the same year (Henderson County Master Gardeners).

Will dianthus bloom again?

Often. Deadhead to the next bud (RHS) or shear after flowering in late summer for a second flush (Almanac).

Why are my pinks dying in winter?

Usually wet soil. The RHS says dianthus are more likely to be damaged by winter wet than cold, and NC State links poor drainage to root and crown rot.

Is dianthus safe for pets?

NC State says the leaves can cause mild stomach upset or skin irritation and flags the genus for dogs, cats and horses. Ask your vet if a pet eats some.