How To Grow Sweet Williams - Flower Patch Farmhouse

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How to Grow Sweet Williams (Dianthus Barbatus)in your Cottage Garden, tough and reliable for years of beautiful blooms.

How to Grow Sweet Williams (Dianthus Barbatus) is for those who want to add a tough and sweet-smelling cottage flower to their garden.

This of those easy cottage flowers that grow well in many zones. Sweet William flowers are considered a biennial or short-lived perennial. When seeded the plant grows one season and blooms the second year and then will reseed itself.

The ones I grow will bloom the first year, I get the Sweet William Lace Mantle seeds at Renees Garden Seeds.

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Today you will discover what growing conditions Sweet William plants like, how to start them from seeds, and how to care for them for a long bloom time.

Why Grow Sweet Williams

Sweet Williams are very easy to grow, will perfume your garden, and bring an element of charm with a long bloom time. For me, scent is a major reason I choose many of the flowers that I grow into my cottage gardens. Many traditional cottage garden flowers are sweetly scented bringing the garden to the next level of beauty!

For more scented flowers for your garden here is an entire post dedicated to flowers to grow for a scented garden.

garden ideas and inspiration

Grow a Sweetly Scented Garden!

discover the joy here!

Adding scent to your garden adds another layer of enjoyment.

What you will learn about Growing Sweet Williams (Dianthus Barbatus)

key takeaways today

• Growing Condtions
• How to start Sweet Williams from seed
• Best growing conditions for success
• How to keep Sweet Williams flowering
• Are Sweet Williams a perennial or annual?
• Are Sweet Williams poisonous to dogs or cats?

Related: Garden Zones, what you need to know!

Growing Conditions

Step 1: Choose the right location

Sweet Williams prefer growing in full sun but will tolerate light shade. They tend to grow taller and get a bit floppy if they get too much shade so if this occurs just plant in a sunnier spot the next time or provide support.

The caveat is if you live in the South with hot summer temps, they will do a bit better with some partial shade, especially in the afternoon.

They also prefer well-drained soil. Before planting, it’s important to prepare the soil by adding compost or well-rotted manure to improve its texture and fertility.

Create Your Own Compost

I like easy and I share how I do it here!

Sweet Williams can also be grown in containers if you have limited space. They are hardy in zones 3 – 9 and can be grown alongside perennials and annuals.

Step 2: Planting Sweet Williams

Sweet Williams can be grown from seeds or transplants. If you are starting from seeds, sow them indoors in early spring or directly in the ground in late summer or early fall.

Cover the seeds with a thin layer of soil and keep them moist until they germinate, which usually takes about 2-3 weeks. Transplants can be planted directly in the ground after the last frost.

When planting, space the plants about 6 to 12 inches apart and plant them at the same depth as they were in their container or the soil level in the seed tray.

Water the plants thoroughly after planting and keep the soil consistently moist until they establish themselves.

If starting indoors sow your seed in your containers 6 to 8 weeks prior to the first frost. I have an entire post on how I start seeds early here.

Or you can winter sow them as I share in this post. This is super easy and successful!

But my favorite way for Sweet Williams takes some patience and is super easy. In late summer scatter the Sweet William seeds on weed-free soil where you want them to grow.

Don’t add a cover of soil, just firmly step on them to make sure there is good contact with the soil. They like loose, rich soil that drains well so don’t press them in too firmly. Keep them watered and watch for the seedlings.

Thin the seedlings once they reach 3 inches tall to 12 inches apart. To thin them I dig them up and replant the seedlings in another area rather than just tossing them in the compost heap or I pot them up to give to garden friends and neighbors.

Thinning helps prevent fungal disease and lets the plants grow with limited disease pressure. By next Spring you should have beautiful sweet-smelling blooms.

Sometimes I don’t get to this job of thinning and they have grown fine, they just did not get as big as they could have. We live in a dry climate so mildew is not typically an issue.

Step 3: Care and Maintenance

Sweet Williams like regular watering, especially during dry spells. If your soil isn’t the best they will benefit from some fertilizer. I prefer to use this liquid organic fertilizer that is cost-effective and earth-friendly.

I add compost to my flower beds each season which acts as a slow-release fertilizer.

To encourage bushier growth and more flowers, pinch back the tips of the plants when they reach about 6 inches in height. This will also help prevent them from becoming too leggy.

Sweet Williams can be prone to powdery mildew, so it’s important to space the plants properly to ensure good air circulation.

Do Sweet Williams Repeat Flower?

Yes! To keep your Sweet Williams blooming you will need to deadhead them.

Watch as the flowers begin to fade and pinch or cut back the stem to half of its growing height. These are my favorite snips for jobs like this.

If you grow a swath of Sweet Williams as I do then cutting each flower when it fades is too much work. Instead, wait for the majority of the flowers to begin to fade and then cut with pruning shears all of the stems to half of the plant height.

Shearing allows you to deadhead all the flowers at once. This will also control the size of overgrown plants and encourage the flowers to bloom again.

Keep watered and watch for fresh blooms.

Let Sweet Williams reseed or not

If you want the Sweet Williams to reseed and grow for you again next season then stop deadheading and let the seeds mature.

Leave all of the seeds to spread on their own for a lot of Sweet Williams or let a few fall to the ground and save the rest of the seeds to give away or plant in other parts of your garden.

To see how I save seeds just hop on over to my Seed Saving for more Garden Blooms article!

Are Sweet Williams a Perennial?

Sweet Williams are a great biennial addition for Spring to Summer bloom with plenty of perfume.

Biennials grow the first year and then bloom the second. That is why you can plant them in late Summer/Early Fall to get growing, then they bloom the following Spring.

As I shared before, I also grow the ones that will bloom the first year. When they reseed themselves an they grow again the next season makes them seem to be a perennial. They are a short-lived one, not a true perennial.

Sweet William Colors

They grow in various shades of red, pink, purple, and white. Some can have a variety of colors on one plant, which is fun too.

Here is a great mix to try Dianthus Sweet William Mix, with lots of colors, and plenty of seed.

This one was a happy accident of many colors cross-pollinating in my garden and producing this gorgeous multi-colored specimen.

They get to about 7 to 18 inches tall depending on the variety and where they are planted.

I have always grown mine from seed or transplanted seedlings from one spot in the garden to another but you can also propagate by cuttings or root divisions.

You can also start them indoors, click here to see my method.

Great for Containers

They do well in pots and can bring a spot of Spring color to many spaces.

Sow your seeds directly in a container filled with good potting soil and keep watered.

Keep in mind that pots and containers dry out more quickly so you may need to water them more frequently than your garden plants.

What makes gardening so easy for me is I tend to favor flowers and plants that thrive in my area. I give them what they need and let them go.

When growing in containers it is easy for the nutrients to be diminished by frequent watering. Be sure and supplement them with this easy to use organic liquid fertilizer every other watering or so.

Are Sweet Williams poisonous to dogs?

Yes, they are mildly toxic to dogs and cats. Though, mildly toxic in most cases, ingestion, if not treated can result in extreme gastrointestinal issues.

Many flowers are toxic to dogs and cats so if you have pets that seem to want to eat your plants you may wish to put any of those types of plants into containers or areas out of their reach.

Or eliminate them from your garden.

For more info on how I garden visit my Lazy Gal Garden Guide posts.

Happy Gardening!

• Hi, I’m Pamela

  With 45 years of hands-on gardening experience, I love sharing practical tips, proven techniques, and inspiration drawn from my own gardens. My goal is to nurture your confidence, spark your passion, and help make every step of your gardening journey more enjoyable.

  Pamela Groppe a Garden Friend!

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