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The mainstay of many English cottage gardens, sweet William blooms are a classic and long-lasting addition to your own landscape once you understand just where, how, and when to plant sweet Williams. While there are plenty of good reasons to grow sweet Williams, inclusion in cut-flower bouquets is easily the most common. But, when left intact, these old-fashioned flowers are also irresistible to hummingbirds, butterflies, bees, and other pollinators. One of the many kinds of carnations, sweet Williams are also known as “pinks”—not for their pink floral hues but, rather, because the edges of their petals appear to have been notched with pinking shears. Read on to learn more about these garden stars.
Meet this unique biennial flower
Technically, sweet William (Dianthus barbatus) is a biennial. That means it puts out foliage in its first year and then flowers in its second year of life. However, depending on your microclimate, hardiness zone, and the decisions you make regarding when to plant sweet Williams, these biennials sometimes can perform more like tender perennials instead.
Not to be confused with other cultivars, Dianthus barbatus has a one-foot spread and will reach 18 to 24 inches tall. (By contrast, there are lower-growing “sweet Williams” like Cheddar pinks (Dianthus grataniapolitensis) which rarely grow taller than six inches and maiden pinks (Dianthus deltoides), a perennial ground cover with a low, mounded habit.)
The ideal site for growing sweet Williams
Before you consider when to plant sweet Williams, you’d better decide just where they’ll thrive for you. Ideally, you should be able to provide your sweet William plants with moist but well-draining soil and full sun. Six to eight hours of sun is ideal. (In very warm climates, try to position plants so that they’ll get some light shade during the hottest part of the day.)
When to plant sweet Williams from seed: 2 options
Wondering when to plant sweet Williams from seed? In areas with very mild winters, you should be able to sow seeds directly in the garden during the fall. Plants will pop up in early to late spring and may even flower lightly during their first year and then more heavily during the second.
As for areas with colder winters? Start your sweet William seeds in pots or seed-starting trays indoors about six to eight weeks before your average last frost date. (And remember to harden off that seed tray full of seedlings before finally installing outside!)
For best results, start seeds in a sterile potting mix and use a seedling heat mat. Your seeds should germinate in five to 10 days.
When to plant sweet Williams from transplants
As for when to plant sweet Williams if you are using transplants? Late spring to very early summer are safe bets. (Essentially, you want to avoid exposing any very young plants to hard frosts.) When planting, position transplants at least eight inches apart to accommodate their spread as mature plants.
How to keep sweet Williams blooming
Besides when to plant sweet Williams for a bright floral show, you’ll also need to know how to get the most out of your sweet William flowers—and how to keep them coming. (Pro-tip: You can create a breathtaking cluster of light to hot pinks, reds, purples, whites, and bicolors by mixing multiple varieties like ‘Red Oeschberg’, ‘White Albus’, and ‘Holborn Glory’, among others.)
If you aren’t regularly cutting blooms for use in bouquets, be sure to cut any spent flowers regularly. Not deadheading the plants and letting the old blooms dry up will spur individual plants to set seed rather than continue to flower.
Overwintering sweet Williams
In part, what you decide about where and when to plant sweet Williams will dictate what you need to do for your plants during winter. For instance, if you grow them in containers, you should store the pots in a spot that won’t go through a hard freeze during winter, such as in a garage. And to help insulate plant roots from the cold, add a layer of mulch, clean, weed-free straw, or dried leaves to planting beds and inside containers.
Caring for the plants
- Food—To ensure you plants have access to the nutrients they need, it’s a good idea to amend your soil with organic matter like aged compost or worm castings. Additionally, you can also apply an organic, all-purpose fertilizer once every couple of months to encourage more robust growth and blooming as needed.
- Water—Plants should be moist but not waterlogged. Feel the top few inches of soil to gauge the moisture level before you water. And while watering, try to avoid splashing plant leaves. (Using a soaker hose is a great way to direct water straight to the plant’s root zone while keeping everything else nice and dry.)
- Breathing room—Regularly weed around individual plants and between rows to reduce competition for light, water, and nutrients. Keeping up with the weeds also improves air circulation between plants.
Troubleshooting problems
Although area deer aren’t likely to devour your sweet William plants, you’re not necessarily in the clear. Dianthus can attract pests like slugs, snails, and aphids. It’s also susceptible to fungal diseases like fusarium wilt and anthracnose. As a result, you should periodically check your sweet William plants for signs of rot or rust and feeding damage.
Seeing leaf spots? How about soft, rotting roots or yellowing foliage? What might have started as simple overwatering can morph into disease. Applying an organic fungicide may help to contain further spread.
In the case of slugs, snails, and aphids, if you look carefully enough you can usually catch them in the act. Control small infestations by hand-picking. Sprinkling diatomaceous earth around your plants is another way to keep the slug and snail populations down. As for those aphids? In the long run, attracting natural predators is best.
Think pinks!
By knowing exactly how and when to plant sweet Williams, you can confidently add their cheerful, long-lasting blooms to container gardens, the borders of perennial beds, and more. Grown in mild climates as a short-lived perennial, Dianthus barbatus shares the “sweet William” moniker with a few other Dianthus types, including lower-growing Cheddar pinks, maiden pinks, and sundry hybrid types. For its part, Dianthus barbatus features a taller growth habit, a fantastic mix of colors, and a faintly clove-like scent, too.
Have a sunny, well-draining spot? Then there’s nothing stopping you from making a bed of sweet Williams to call your own.
Meet more great flowers for the garden in these articles:
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