(Photo courtesy of NetPS Plant Finder)
Height: 24 inches
Spread: 24 inches
Hardiness Zone: 2a
Other Names: Squarerose Knapweed
An interesting perennial with long gray green leaves that have a woolly appearance the circular flowers are bluish tones that fade to white, with violet centers; good cut flowers; plants do better if lime is added to soil; pollution and salt tolerant
Knapweed features unusual sky blue lacecap flowers with white overtones and purple anthers at the ends of the stems from late spring to early summer. The flowers are excellent for cutting. Its tomentose narrow leaves remain grayish green in color throughout the season.
Knapweed is an herbaceous perennial with an upright spreading habit of growth. Its medium texture blends into the garden, but can always be balanced by a couple of finer or coarser plants for an effective composition.
This plant will require occasional maintenance and upkeep, and is best cleaned up in early spring before it resumes active growth for the season. It is a good choice for attracting butterflies to your yard, but is not particularly attractive to deer who tend to leave it alone in favor of tastier treats. Gardeners should be aware of the following characteristic(s) that may warrant special consideration;
Knapweed is recommended for the following landscape applications;
- Mass Planting
- General Garden Use
- Naturalizing And Woodland Gardens
Planting & Growing
Knapweed will grow to be about 24 inches tall at maturity, with a spread of 24 inches. The flower stalks can be weak and so it may require staking in exposed sites or excessively rich soils. It grows at a fast rate, and under ideal conditions can be expected to live for approximately 15 years. As an herbaceous perennial, this plant will usually die back to the crown each winter, and will regrow from the base each spring. Be careful not to disturb the crown in late winter when it may not be readily seen!
This plant should only be grown in full sunlight. It is very adaptable to both dry and moist locations, and should do just fine under typical garden conditions. It is considered to be drought-tolerant, and thus makes an ideal choice for a low-water garden or xeriscape application. It is not particular as to soil type or pH, and is able to handle environmental salt. It is highly tolerant of urban pollution and will even thrive in inner city environments. This species is not originally from North America.