How to Grow Sweet William, a Cottage Garden Favorite
I love heirloom flowers. I love the idea of growing plants in my garden that were grown hundreds of years ago. One of my favorites is sweet william. It was grown in gardens in the time of Shakespeare.
What is Sweet William?
Sweet William (Dianthus barbatus) are biennials or short lived perennials that are often grown as annuals. A short lived perennial is a perennial that lives only a few years instead of the 7 t 9 years that is normal for most perennials. Most gardeners purchase second year plants from their local nursery so that they will bloom during the summer and then they remove them from their gardens in the fall after the frost along with their annual flowers.
Sweet William are related to carnations. They are native to two areas of the world. D. barbatus var. barbatus is native to Southern Europe. This is the plant most commonly grown in our gardens. D. barbatus var. asiaticus is native to northeastern Asia.
Sweet william was introduced into northern Europe in the 16th century. It made its way to North America with the European settlers and has naturalized here.
The European sweet william are hardy in USDA growing zones 3 – 9. They grow 1 to 2 feet tall with lance shaped leaves unlike the more grassy leaves of their cousins the carnations.
The flowers look like carnations, but instead of appearing singly on stalks, they grow in large clusters known as umbels. Each flower has five petals with serrated edges. The colors range is the same as carnations: red, pink, white and bicolors. The older cultivars have a clove like scent while the newer hybrids do not. This often happens with flowers. As you breed for specific colors, flower forms or size, you lose the scent. Most gardeners don’t mind but I grow sweet william for both its flowers and its scent so there are no fancy double flowers in my garden. Instead when they bloom, there is an intense fragrance that greets me every time I step out of my door.
How to Grow Sweet William
Sweet william loves to grow in rich, well-drained loamy soil in full sun. It can grow in partial shade but won’t flower as well. In areas of the country with very hot summers, it appreciates some shade in the afternoon. Keep your plants moist, about 1 inch of water per week. A thick layer of mulch will help keep the soil moist and prevent weeds from growing in your garden.
Bloom time is late spring to early summer. If you deadhead the flowers, you may get a second flush of flowers. A lot of gardeners allow their plants to go to seed so that they will reseed in the garden. This is a great way to ensure that a short-lived perennial will continue to grow in your garden year after year. Just be aware that the double flowers will not come true from seed. They are hybrids. In fact, if you allow sweet william to reseed for enough years as I have, you will discover that they eventually revert back to the original red flowers with white bases of their ancestors.
In the fall, the plants will die with the frost. Cut them down to the soil level and remove them from your garden so that harmful insects cannot use the plant debris to hibernate in over the winter. Do not pull the plants out of the ground. Leave the roots alone. They will remain dormant in the soil, then grow new plants in the spring. If they don’t grow again in the spring, then you can remove the roots that have died.
How to Grow Sweet William From Seed
I have never purchased plants because sweet william is so easy to grow from . Plus by buying seeds, I can get the old-fashioned varieties with the wonderful scent. You can direct sow your seeds in your garden after your last frost. Plant them 1/16 inches deep. Germination should occur in 1 to 2 weeks. Thin your seedlings to 6 inches apart. They will bloom the following year. seed
You can also start your seed indoors 6 to 8 weeks before your last frost. Plant the seeds in containers filled with pre-moistened soil 1/16 inches deep. Moistening the soil before you plant the seeds is critical when the seeds are at such a shallow depth. If you wait until after your plant the seeds to water the soil, the seeds will just float away and may even float out of the container if any water runs over the side of the container. I always water first when planting seeds.
Germination should occur in 1 to 2 weeks. You can transplant your seedlings outdoors into your garden after your last frost. Space them at least 6 inches apart. Your plants will bloom the following year.
© 2020 Caren White