How to Grow Carnation Flowers in Your Home Garden

Depending on where you live, there are as many as 300 different types of carnation and carnation hybrids to choose from, in annual, biennial, and perennial varieties with a full spectrum of shades and petal shapes. Most cultivars thrive in USDA hardiness zones 5–9.

Tall, leggy varieties like the ones seen in bouquets aren’t typically sold for home cultivation, but some of the most commonly grown varieties are Chabauds (Dianthus caryophyllus), which serves up an iconic tightly-packed, deeply aromatic blossom. Most chabaud carnation seeds are sold in packs of different colors for a multicolored cutting garden.

Another favorite is the “Sweet William” (Dianthus barbatus), which can feature a starburst-colored flower, often electric pink at the center and fading to white at the edges with sharply serrated petals.

Carnations begin to bloom in late spring, usually May. Depending on the location and variety, their growing season can last deep into summer; like roses and hydrangeas, regular cutting and deadheading of blossoms will stimulate new buds and extend a plant’s bloom time.

There are a few widely used approaches to growing carnations from seed: You can start carnations indoors in seed-starting potting mix and transplant outdoors; sow directly in the ground; or cultivate in containers. Most plants won’t produce flowers in their first year, so patience is key.

1. 1. Choose the site. Carnations prefer full sun, and a well-draining, fertile soil that’s slightly alkaline, with a pH around 6.7 to thrive. Choose a planting site that receives at six hours of sunlight per day.
2. 2. Prepare the site. A few days before planting, combine potting mix with a few inches of aged organic material like compost to ensure good soil health.
3. 3. Start seeds indoors. If you choose to start carnation seeds indoors, you can do so up to eight weeks before your area’s last frost date. Sprinkle seeds over a starter potting soil mix in starter trays (both of which can be found at a garden center or nursery), and cover with a very light layer of soil. Mist to keep the soil moist, and cover loosely with a plastic bag to simulate a warm, greenhouse environment. When using the plastic bag method, you’ll need to look out for mildew on the surface of the soil. If it becomes too moist, remove the plastic bag, and allow the soil to slightly dry out.
4. 4. Plant. Plant carnations in early spring, about two weeks after the last frost date. Indoor seedlings are ready for transplanting when they reach five inches in height. Dig holes the same size as the starter pot—space the holes a foot or so apart if planting multiples. If pots are peat or biodegradable, place directly in the ground and fill in with soil; if not, carefully wiggle the container off to avoid damaging the young roots and place in soil. After placing the plant in the hole, gently tamp down the soil, and water well. If sowing seeds outdoors, place them ¼ inch deep in the soil and lightly cover with topsoil. Keep moist; once seedlings appear, thin to about 10 inches apart to give the plants room to grow.

Carnation plants require a few simple maintenance routines:

• Water. Water new plants deeply once a week—soaker hoses are great for this—to help establish root systems. After establishing the roots, you’ll only need to water the flowers when the top inch of soil is completely dry. If possible, stick to a morning watering schedule to give the plant’s delicate leaves a chance to dry out in the heat of the afternoon to prevent mildew.
• Mulch. Surrounding carnation plants with a layer of mulch (for perennial plants, shredded bark is ideal) keeps weeds at bay, as well as maintaining soil temperature and moisture.
• Control pests. Carnations are targets for pests like aphids, mites, and thrips. Practice companion planting as a natural insect deterrent, or introduce predators like ladybugs to control the population. Depending on the severity of the infestation, you may need to apply a mild insecticidal soap to plants, but in most cases, a strong blast of water every few days or so may do the trick.
  
• Deadhead. Cut flower stems regularly, and clip away any spent flowers to encourage a longer blooming season and stimulate new plant growth. Pruning will also help with air circulation, which can help prevent powdery mildew and other fungal diseases.

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