If you’d like to try growing carnations (Dianthus), starting with seeds is one of the best options, in my experience. This will allow you to grow many different types of carnations and give you the satisfaction of seeing these plants go from seed to flower. In this guide, I’ll share my essential tips and experience of how to grow carnation flowers from seed.
Selecting Carnation Seeds
One key tip to follow is to always start with new carnation seeds. Most reputable seed companies will list the germination rates on their seed packages.
You can also look at the seed packet for information such as days to maturity and seed planting depth.
If you’re in need of some inspiration, see our guide to the most fragrant types of carnation flowers.
Starting Carnation Seeds Indoors
If you want to plant carnations out in the garden as early as possible, the best plan of action is to start the carnation seeds indoors. This allows you to get a jump on the growing season when it is still cold outside.
When to Plant Carnation Flower Seeds Indoors
In my experience, carnations take about 6–8 weeks from planting the seeds to when the seedlings are ready for transplant. That means you should start seeds indoors about 6–8 weeks before the predicted last frost date.
For example, since the last spring first typically occurs in mid-April where I live, I will plant my carnation seeds sometime during the middle or end of February.
Choosing Seedling Containers
I like to start flower seeds like carnations in 72-cell trays (via Amazon). However, you can also plant your seeds in 50-cell trays, larger plastic pots, or even old plastic yogurt containers. If you choose to reuse containers, make sure to poke drainage holes in the bottom.
You can also start seeds in open trays (via Amazon) and then move them to individual pots once the seedlings have their first set of true leaves.
Selecting a Potting Mix
If you plant seeds indoors, you’ll want to choose a rich yet well-draining soilless potting mix. The mix should provide the structure and nutrients carnation seedlings need to develop strong roots, leaves, and stems.
Planting Carnation Flower Seeds
Once you have your seed trays and potting mix, it’s time to plant your seeds. Begin by adding water to the potting soil so it is moist but not wet—it should feel moist to the touch but not be dripping water.
Scoop the potting mix into your seedling trays and gently tap them on a hard surface to let the mix settle a bit. Then, fill the newly emerged empty space with more potting mix.
Use your finger to make a shallow indent where you would like to place each seed. The indentation should be about ¼ of an inch deep.
I place one carnation seed into each hole and then fill the hole with more potting mix. Gently water the seeds so the soil mix is damp.
I find the best results are to keep the seeds somewhere between 65–75°F and water when the soil mix begins to dry out. From experience, the seeds should germinate within one to two weeks.
Caring for Carnation Seedlings
Once the seeds have sprouted, you must ensure they receive at least ten hours of bright light each day. If you have a greenhouse or temperatures are constantly above 60°F, you can place the seedlings outdoors.
However, if you are starting the seeds indoors, you can place the seedlings under grow lights. I like to use T5 grow lights (via Amazon) and position them about six inches above the top of the seedlings.
Continue to water the seedlings when the soil begins to dry out. I find that I need to water my seedlings anywhere from twice a day to every other day, depending on the temperature, humidity, and wind.
Planting Carnation Seedlings Outdoors
Once your carnation seeds are about six weeks old, you can plant them outdoors. However, you’ll want to ensure that the danger of frost has passed before you do so.
Space the seedlings between 10–12 inches apart when you plant them outdoors.
To mitigate common issues, see our essential guide to why your carnation plant isn’t flowering.
Growing carnations from seed is a rewarding project that can boost your gardening confidence and provide you with fresh flowers.
Further reading: Discover our in-depth guide to 40 amazing types of carnation flowers to grow in your garden,.
Briana holds a B.S. in Plant Sciences from Penn State University. She manages a small market garden where she grows vegetables and herbs. She also enjoys growing flowers and houseplants at home.