Each year the Perennial Plant Association names a plant as its Perennial Plant of the Year. This year they have named Allium ‘Millenium’ as their 2018 Perennial Plant of the Year. University of Illinois Extension Horticulture Educator Martha Smith offers the following information on this herbaceous perennial that is a workhorse in the late summer garden.
The genus Allium contains over 900 species of bulbous plants, but is best known for a dozen or so species that compose the culinary vegetables and herbs: onion, garlic, leeks, shallots, scallions, and chives. The genus is also known for a few dozen ornamental flowers that grow from bulbs and sport tall stems with big globe-shaped blooms in spring.
Allium ‘Millenium’ can help liven the landscape in several ways. It grows best in full sun. Each bulb typically produces a clump of upright grass-like foliage that has glossy, deep green leaves that will become 10-15 inches tall in spring. In midsummer, two or three flower scapes appear from each bulb. Each scape will produce two to three showy two-inch spherical flower heads that are rose-purple in color. The flowers can last for up to four weeks. The flowers will dry to a light tan, often holding a blush of their former rose-purple color.
You can expect a good display with three to five bulbs per one-gallon container. Free draining soil medium and full sun are required. Once in the garden, ‘Millenium’ can easily be lifted and divided in either spring or fall. Cut back foliage in late fall.
While most other Alliums end up looking scraggly in the heat of the summer, ‘Millenium’ doesn’t let the heat bother it. Easily grown in Zones 4-9, it makes a great perennial in many areas of the country. In very hot summer climates, it does appreciate afternoon shade.
No serious pest or disease problems have been reported except for bulb rot, which may occur in wet soils. In overcrowded growing conditions, plants may also suffer from leaf spot. An additional benefit is that deer and rabbits leave ‘Millenium’ alone. While deer and rabbits may not enjoy ‘Millenium’, pollinators will flock to it.
Often times people avoid growing Alliums because of their reseeding behavior. Fortunately, ‘Millenium’ produces 50 percent fewer seeds and therefore less potential for self-sown seedlings.
This low-maintenance dependable perennial will not disappoint. It blooms at a time when most of our garden begins to decline and offers much needed color. It is truly an all-season plant offering attractive shiny foliage spring through summer and capping off the season with its crown of perfectly round, rose-purple flowers.