Fascinated with carnations? Consider experimenting with growing carnations. The most commonly known carnation flower—florist’s carnation (Dianthus caryophyllus)—is the one typically seen in bouquets with large blossoms and serrated petals. In the home garden, this carnation requires considerable effort to get the quality of blooms you see in a florist shop. But growing carnations is possible, including this type along with several others.
Florist’s carnation is also known as a perpetual flowering carnation. For the commercial florist trade, these plants are typically raised in greenhouses in Colombia, Israel and Spain. In the controlled environment of a greenhouse, growing carnations is a very regimented process—which is why these plants yield the large bloom size.
In the home garden, growing carnations typically produces flowers in the 2- to 3-inch range. The plants tend to be somewhat floppy because the flowers weigh too much for stems to support, so it’s important to stake plants. An effective way to make growing carnations easier is to use grow-through stakes or create a grid of strings that you can weave carnation stems through for support.
Most often professional growers start florist’s carnations from cuttings they take from side shoots or small plantlets or suckers that form around the stem bases. Home gardeners typically buy carnation plants as perennials. Carnations are hardy in Zones 5 or 6 to 9, depending on the variety. These are short-lived perennials, typically blooming strongly for only three to four years. Plan to divide carnations whenever growth in the middle of a clump starts to die.
The reason professional flower growers don’t sow florist’s carnation seeds is that it takes from 12 to 24 months for plants to bloom. In the home garden, florist’s carnations grown from seed are usually treated as annuals.
Other types of carnations that grow well in the home garden include border carnations (Dianthus x allwoodii), which are shorter perennials that grow 4 to 18 inches tall and up to 18 inches wide. These plants yield abundant flowers with the classic carnation flower form and last well in bouquets. Smaller carnation cousins include sweet William (Dianthus barbatus), a short-lived perennial, and china pinks (Dianthus chinensis), a short-lived perennial often grown as a biennial. All of these carnation types offer fringed petals and clove-scented flowers.
You can start the different types of carnation seeds indoors, and most also grow well using winter sowing techniques. Sweet William and china pinks thrive in cool weather and sprout readily when directly planted into flower beds. These plants readily self-sow and can establish a reliable presence in a flower bed.
All carnations need well-drained soil that’s light and fertile. Heavy clay soil is a death sentence when growing carnations of any type. Amend heavy clay with organic matter, gypsum or lime. A soil test will help you know what you should add. Carnations are susceptible to a variety of leaf and flower diseases that spread easily through overhead watering. Use drip irrigation, microsprinklers or soaker hoses to deliver water directly to soil.