Dianthus caryophyllus "Sweet William" is mildly toxic to dogs. If you're a dog owner, consider eliminating the plant from your gardening scheme. Although it won't kill your dog, the plant does cause problems if your dog eats too much of it.
Sweet William Basics
Sweet William is a breed of carnation that is desirable in most gardens because it is multicoloured in brilliant red and salmon pink or pure white. Sweet Williams are also hardy plants that, "are affected by few pests, grow vigorously in an average soil and are not too demanding so far as water is concerned," according to Plant-Care. Sweet Williams are used as colourful borders, in planters throughout the yard, window boxes and included in flower gardens.
Sweet William was previously deemed safe to eat, however, as of 2011, the ASPCA reclassified the Sweet William as an "unknown irritant." It is also not known which part of the plant is most irritating to your dog should it eat it, the leaves, stems or buds. It's best to keep your canine away from the entire plant. Sweet William is also mildly toxic to cats, which are much more prone to eat plants.
If your dog does eat sweet william, it suffers, "mild gastrointestinal signs, mild dermatitis," warns the ASPCA. Your dog will probably drool, throw up, may get diarrhoea and possibly break out in hives or a rash. Although these symptoms are classified as mild, they are extremely uncomfortable for your dog. If left untreated, it could lead to more dangerous health issues, such as dehydration.
What to Do
If you suspect your dog has eaten sweet william, take it and a cutting from the plant to the vet for the appropriate medical diagnosis and treatment. Although this plant is only mildly toxic to dogs, take no chances with your canine's health. Excessive vomiting, diarrhoea or severe dermatitis after your dog has completely expelled the sweet william may indicate something more serious going on, such as an allergic reaction to the plant. Taking a portion of the plant to the veterinarian with you helps your vet determine exactly why this perennial is causing your canine such distress.
Planting Sweet William
Sweet William thrives in areas with a lot of sunshine. Plant your sweet williams approximately 6 to 12 inches apart in the spring or fall in about 12 to 15 inches of tilled soil mixed with a 2- to 4-inch layer of compost. The National Gardening Association recommends removing sweet william from its nursery pot and placing it in your freshly tilled soil so the root ball is, "level with the soil surface." Gently pat the dirt in around the root ball and give sweet william a thorough dousing of water. If you've planted your Sweet Williams in a soil with a neutral to alkaline pH where they can sunbathe all day and kept them moist, but not too wet, certain sweet williams might grow as tall as 2 feet.