Carnations (Dianthus caryophyllus) are popular flowering plants known for their vibrant colors and long vase life. As temperate plants, they thrive under specific temperature conditions that balance growth, flowering, and overall health. Understanding their ideal temperature range is critical for optimal cultivation, whether in greenhouses, gardens, or indoor settings.
During the day, carnations perform best in temperatures between 18°C to 24°C (64°F to 75°F). This range supports photosynthesis, nutrient uptake, and robust stem development. Temperatures above 25°C (77°F) may stress the plant, leading to reduced flower size and accelerated aging, while prolonged exposure to temperatures below 15°C (59°F) can slow growth and delay flowering.
Carnations benefit from cooler nighttime temperatures, ideally between 10°C to 15°C (50°F to 59°F). This diurnal temperature variation mimics their natural habitat and promotes healthier root development and flower pigmentation. Consistently high nighttime temperatures (above 18°C/64°F) can weaken stems and reduce flower quality.
For seed germination, carnations require slightly warmer conditions, around 21°C to 23°C (70°F to 73°F). Once seedlings emerge, temperatures should be gradually reduced to 15°C–18°C (59°F–64°F) to encourage sturdy growth. Excessive heat during this stage can lead to leggy, weak plants.
Flower initiation and development are highly temperature-sensitive. Carnations require cooler temperatures (10°C–15°C/50°F–59°F) during the bud formation phase to ensure uniform blooming. High temperatures during this period can cause bud abortion or irregular flowering. Maintaining stable temperatures avoids stress-induced deformities in petals.
Carnations can tolerate brief exposure to temperatures as low as 0°C (32°F) or as high as 30°C (86°F), but prolonged extremes are detrimental. Frost damages foliage and buds, while heatwaves increase susceptibility to pests like spider mites and diseases such as Fusarium wilt.
In temperate climates, carnations grow best in spring and fall when temperatures align with their ideal range. Summer heat may necessitate shade cloth or misting, while winter protection (e.g., mulching or row covers) is needed in colder regions. Greenhouse growers often use ventilation and heating systems to maintain consistent temperatures year-round.
Temperature influences carnations' water and light requirements. Higher temperatures increase transpiration, demanding more frequent irrigation, while low temperatures reduce nutrient absorption efficiency. Light intensity should be balanced with temperature; high light + high heat can scorch leaves, whereas low light + cool temps may stunt growth.
