How to grow and care for sweet william - the ultimate plant to add vintage style and colour to your garden

Rosette shaped and rich in a variety of colours, knowing how to grow and care for sweet william (Dianthus Barbatus) will inject a touch of old-fashioned appeal into your garden borders. 

These deliciously fragrant flowers, perhaps, have that same old-school simplicity as carnations. Being from the same family they resemble them too; tall and lush green stems grow to about 50 centimetres tall and fan out compact petals in vivid shades, often two-toned, ranging from deep purple to bright white. 

And, what's more, the delightful cottage garden idea staples are just as easy to grow as they are to look at. You can even sow their seeds straight into the ground. As we see a rise in cottagecore interiors and country garden plots, we've asked the experts how to grow and care for sweet william. 

How to grow and care for sweet william

Want to learn how to grow and grow sweet william to enjoy the budget-friendly and low-maintenance charmers during high summer? We've asked the experts what's needed to bring the beauties to life. Patience is the key to sweet-smelling success.

Where to buy sweet williams

How to grow sweet william from seeds

Growing sweet william from seeds is a budget garden idea that will have your flower beds bursting with colour next year. 

The first rule of sweet william success is to ensure you've completed your spring gardening job list so garden beds and borders are weed-free. 

'Sweet william seeds can be sown directly into the ground where you want to grow them, but you will first need to ensure that the soil is weed-free. The seeds are best planted in July, and they should then produce flowers the following summer,' explains Martin Donnelly, a horticultural expert from LBS Horticulture.

'Rake the soil to a fine tilth, and create channels in the ground that are roughly 5 millimetres deep. If planting in rows, these should be at least 30 centimetres apart.'

'If you are planting in dry soil, water the soil before sowing and allow it to drain. Sprinkle the seed thinly along the channel, and cover them with soil. If the plants are crowded as they grow, they can be thinned out to around 15 centimetres apart.'

How to grow and care for Sweet William plugs

If you have grown sweet williams from seed they should grow into their vegetative stage` by autumn and can be re-arranged to avoid cramping. 

'In autumn, move the plants so that they are 30 centimetres apart and will not be too crowded once they begin to flower. Sweet williams should be kept well watered in periods of dry weather, and flowers should appear in the next summer.'

Alternatively, sweet william plugs can be bought from nursery centres and planted in the ground at this time. The plants love fun sun so plant them away from shade.

'Plant 9” – 12” apart into fertile, well-drained soil. Allow plenty of space to prevent plants being affected by mildew. These young plants are hardy and will overwinter in the ground,' explains Nicola Bradley, Head Gardener at The Lost Gardens of Heligan.

How to care for Sweet William

Sweet william is an over-wintering plant there so shouldn't be affected by frost. Once spring arrives the hibernators will enjoy a good feed when they wake up and will require the same every 6-8 weeks as they grow.

'In early spring apply a top dressing of well-balanced fertiliser to give the plants a boost. Make sure you keep the area weed-free,' says Nicola.

'In Cornwall, our plants usually flower from late May onwards. I would also suggest to deadhead regularly to prolong the flowering period.'

Water regularly during their growing season taking care not to waterlog. 

FAQs

How long does Sweet William last

Sweet william can be cut down to its base during late summer (when flowering has finished) to encourage new growth for another year. However, as these plants are short-lived, it may be more practical to purchase new ones and grow them as annuals each year.

'Once flowering is over we remove our plants and compost, sowing new plants each year. They can be left as a short-lived perennial, but we find we get a better display when grown as a biennial,' agrees Nicola.

What's the difference between sweet william and pinks?

Sweet william's botanical plant name is Dianthus barbatus. Sweet william, carnations and pinks are all Dianthus.

Pinks and carnations are short-lived perennials and re-bloom over a few cycles. Sweet William on the other hand are biennials so will grow and bloom in their first year and die off in their second.

Bring back this classic colourful plant to your garden and start planting this weekend.