Carnation is the common name of the Dianthus family of plants that has over 300 different species within it. When to plant carnations for best results in your area depends on what kind of carnation you are attempting to grow. Carnations come in three main varieties: annuals, perennials, and biennials. Carnations can be propagated in all areas of the world throughout the calendar year, but they are native to the temperate regions and summers of Europe and North America.
When to Plant Outdoors
Annuals and perennials should be planted outside between the end of autumn and the last frost. If growing from seed instead of cuttings, these seeds must be covered to prevent them from being damaged by the frost. Biennials should be sown in late spring or early summer. When planting outdoors, all carnations should be spaced at least eight inches apart. Carnations require full sun and well-drained soils, so do not plant them outside in your area during seasons that are typically rainy or overcast. Further, do not plant carnations until you are certain that the final frost of the season has ended.
When to Plant Inside
All three major types of carnations can also be grown inside. Annuals and perennials should be planted approximately ten weeks in advance of when they are needed. They can be transplanted outdoors after the final frost of the season. Biennials, on the other hand, should be planted eight weeks in advance and should be transplanted outside in August. All styles of carnation have an approximately two week germination period.