How To Grow Sweet William

Sweet William is a traditional cottage plant famous for its late spring and early summer colour and sweet peppery perfume. Dense clusters of flowers are produced on sturdy self-supporting, well-branched stems in a superb mix of complementary colours.

It’s also prized as a cut flower to bring indoors. Learn how to grow Sweet William in our growing guide.

What are Sweet William’s?

Sweet william is a beautiful, colourful biennial flower that will reseed itself. The plant grows for two years, blooming in the second year. The compact size of Sweet Williams makes them great for containers and pots or on a windowsill. Despite their small size, they also make good cut flowers – all they need for indoor splendour is a small vase.

You’ll quickly discover when growing sweet william that their nectar will attract bees, butterflies and birds to your flower beds, making it a great choice for a wildlife orientated garden. The leaves are tapered and the flowers grow in clusters at the top of the stems.

When to plant Sweet William

For autumn bedding, plant out your plug plants from mid-September to early October, depending on the size of the plants acquired. Grow on plants indoors until they reach 8 to 10 cm in height at which point they’re ready to plant out. 

How and where to plant Sweet William

You should ideally, plant your sweet williams in an area with full sun, though a partial or light shade can be tolerated. The soil conditions should be slightly alkaline, fairly rich, quite loose and well-draining. 

Make sure to mix in a general garden fertiliser before planting out, and then every 6 weeks. If the general temperature is going to be hotter than average, then choose to plant out in a shadier location to offset this.

If you’re planting in a bed or border use a trowel to dig an individual hole for each plant, deep enough to submerge the root ball and keep the base of the stem at soil level. Position your plant and fill the hole back in. Gently firm down and water in. Leave a 15 cm space between plants, and bear in mind that the plants will grow to a height of between 20 and 40 cm.

When do Sweet William flower?

Sweet william flowers are five-petaled and around 2 to 3 cm in diameter and will bloom in late spring/early summer. The petals also have serrated edges. Regular deadheading will encourage further flowering – however, bear in mind that sweet williams is self-seeding so you need to keep enough flower heads to provide the seed for next year.

How to care for Sweet William

Make sure to regularly weed around your Sweet Williams as they are growing as weeds will compete for nutrients and water.

You should also apply a layer of mulch once the plants are established and inspect the plants for any signs of aphids, nematodes or slugs, and remove or apply appropriate deterrents as necessary.

For more advice on how to deal with garden pests such as aphids and slugs & snails check out our gardening advice section.

Feeling inspired? Take a look at our Sweet William collection.