How to Care for Carnations: Plants and Cut Flowers

The carnation, known scientifically as Dianthus caryophyllus, is a globally recognized flower appreciated for its ruffled, full-bodied blooms and extensive color palette. Its enduring popularity stems from its versatility as both a durable garden perennial and a long-lasting cut flower. With a subtle, clove-like fragrance, carnations have been cultivated for centuries, finding a place in gardens and floral arrangements alike. This flower’s resilience and classic appearance make it a favorite for many occasions.

Ideal Growing Conditions

For carnations to flourish, they require a location that receives at least six hours of direct sunlight each day. Morning sun is particularly beneficial as it is less intense than the afternoon sun, which can sometimes cause the vibrant colors of the petals to fade. Without adequate light, flowering can be sparse and the plant’s overall vigor may decline.

They demand well-draining soil to prevent root issues. This means the soil allows water to pass through at a moderate rate, preventing it from becoming waterlogged. Heavy clay soils, which retain too much moisture, should be amended with organic matter like compost to improve their structure and drainage.

Carnations prefer a slightly alkaline soil, with a pH level between 6.7 and 7.0. If your garden soil is naturally acidic, incorporating a small amount of garden lime during planting can help raise the pH to a more suitable level for these plants.

Placing carnations approximately 10 to 18 inches apart provides sufficient room for growth and promotes good air circulation around each plant. This airflow is instrumental in drying foliage quickly after rain or watering, which significantly reduces the risk of fungal diseases developing. Most carnation varieties are suited for USDA hardiness zones 7-10, where they can survive as perennials.

Routine Carnation Plant Care

Consistent watering is important for carnations, especially during the spring when flower buds are forming. The best practice is to water deeply at the base of the plant, allowing the soil to dry out moderately between waterings. Keeping the foliage dry by avoiding overhead watering helps prevent the onset of common fungal issues.

To support vigorous growth and continuous blooming, a regular fertilizing schedule is beneficial during the growing season. A balanced, water-soluble fertilizer applied every four to six weeks can provide the necessary nutrients. It is advisable to use a formula that is not excessively high in nitrogen, as this can promote lush foliage at the expense of flower production.

Pruning and deadheading are regular tasks that encourage a carnation plant to produce more flowers and maintain a tidy shape. Deadheading, the process of removing spent blooms, redirects the plant’s energy into creating new flowers rather than producing seeds. After the first major frost in the fall, you can prune the plant back to a few inches above the ground.

Managing Pests and Diseases

Carnation plants may occasionally attract common garden pests, with aphids and spider mites being two of the more frequent visitors. Aphids cluster on new growth, while spider mites create fine webbing on the plant. Both pests can be managed effectively by spraying the affected areas with a gentle stream of water or by applying insecticidal soap.

Fungal diseases such as rust and fusarium wilt can also affect carnations, particularly in humid conditions or when plants are too crowded. Rust appears as small, reddish-brown pustules on the undersides of leaves, while fusarium wilt causes the lower leaves to yellow and the plant to wilt, often starting on one side. If a plant becomes infected with fusarium wilt, it should be removed to prevent the disease from spreading through the soil.

Extending the Life of Cut Carnations

The stems should be re-cut at a sharp angle, preferably under running water or in a basin of water. This prevents air bubbles from entering the stems, which blocks water uptake and causes premature wilting. Removing any leaves that will sit below the waterline in the vase is also necessary to prevent bacterial growth in the water.

Always use a clean vase to reduce the presence of bacteria that can contaminate the water and harm the flowers. Adding a commercial flower food packet to the water provides the carnations with the necessary carbohydrates and biocides to thrive. The water should be completely changed every one to two days, and the stems should be re-cut each time to ensure they can continue to absorb water efficiently.

The arrangement should be kept out of direct sunlight and away from sources of heat, such as vents or appliances, as warmth can accelerate the aging process of the flowers. It is also wise to keep the vase away from ripening fruit. Many fruits release ethylene gas as they ripen, a plant hormone that causes flowers to mature and fade more quickly.