Allium ‘Purple Sensation’

* Common name: Ornamental onion ‘Purple Sensation’

* Botanical name: Allium hollandicum ‘Purple Sensation’

* What it is: ‘Purple Sensation’ is a variety of ornamental onion that produces three-inch-round, golfball-sized violet-purple flowers in May.

   The lollipop-like flowers grow at the tips of the two- to three-foot-tall flower stalks, which are surrounded by green strappy leaves.

   ‘Purple Sensation’ is a winter-hardy bulb that’s best planted from late September through October. Foliage emerges the following spring and each spring thereafter before dying back and going dormant in summer.

   Deer and rabbits have no interest in this onion-family plant grown for its ornamental value. However, bees and butterflies like the flowers, and some of the flowers can be cut for vase use.

* Size: Foliage grows about 18 inches tall, and flower stalks and flowers poke up another foot. Plant bulbs eight inches deep and eight inches apart.

* Where to use: ‘Purple Sensation’ is at its best when planted in masses or clusters of at least a dozen in sunny borders, sunny house foundations, along walkways, and in rock gardens, although plants also can be spotted among other spring-blooming perennials for a “meadowish” look. It’s also a top choice in any children’s garden.

   As with all ornamental onions, ‘Purple Sensation’ performs best in full sun and well drained soil, especially in slightly raised beds.

* Care: Water the bed after planting in fall, and top the soil with two inches of mulch. No need to fertilize at this point. The needed first-year nutrition is already stored in the bulbs.

   In ensuing years, scatter an organic, granular bulb fertilizer over the bed in early spring and early fall.

   Snip off flower stalks when blooms fade, but wait until foliage browns or at least yellows in early summer before cutting it.

   Water is not needed once bulbs go dormant in summer – no matter how hot or dry it gets.

   If clumps are getting thick after several years, bulbs can be dug, divided, and used in other areas or given away. Dig the clumps right after the plants go dormant in summer, separate the bulbs, then replant immediately as you would new ones. No need to wait until October.

* Great partners: Pink-blooming shrub roses and spirea often overlap bloom time. Salvia, peonies, and bearded irises are good perennial partners that bloom at the same time.

   Hollies and boxwoods are good evergreen neighbors.

   Interplant with dahlia tubers, which will take over the space in summer as ‘Purple Sensation’s’ leaves go dormant.

   Annual flowers also can be planted between the bulbs once the alliums are dormant.