Blue Corkscrew Onion
Allium senescens 'var. glauca'
Blue Corkscrew Onion flowers
(Photo courtesy of NetPS Plant Finder)
Plant Height: 12 inches
Flower Height: 24 inches
Spread: 12 inches
Hardiness Zone: 2a
Other Names: Flowering Onion
Blue Corkscrew Onion has masses of beautiful balls of lightly-scented lavender flowers at the ends of the stems from late spring to early summer, which are most effective when planted in groupings. Its sword-like leaves remain green in color throughout the season. The fruit is not ornamentally significant.
Blue Corkscrew Onion is an open herbaceous perennial with tall flower stalks held atop a low mound of foliage. 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 is a relatively low maintenance plant, and should only be pruned after flowering to avoid removing any of the current season's flowers. 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. It has no significant negative characteristics.
Blue Corkscrew Onion is recommended for the following landscape applications;
Planting & Growing
Blue Corkscrew Onion will grow to be about 12 inches tall at maturity extending to 24 inches tall with the flowers, with a spread of 12 inches. It grows at a medium rate, and under ideal conditions can be expected to live for approximately 5 years. As this plant tends to go dormant in summer, it is best interplanted with late-season bloomers to hide the dying foliage.
This plant should only be grown in full sunlight. It does best in average to evenly moist conditions, but will not tolerate standing water. 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 is a selected variety of a species not originally from North America. It can be propagated by multiplication of the underground bulbs; however, as a cultivated variety, be aware that it may be subject to certain restrictions or prohibitions on propagation.