Add Oomph to Your Garden With Ornamental Onions

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Stunning, star-shaped and super easy, ornamental onions, of the genus Allium, add a touch of glamour to your garden. Fall is the best time to plant these deer-and rodent-resistant bulbs.

There are several species of Allium or onion that are grown wholly for their flowers and not for eating their bulbs. Ornamental onions can play a starring role in beds or borders with other perennial flowers, while their edible distant cousins, such as the short day onion Yellow Granex (Allium cepa), or Garlic (Allium sativum), are planted in the vegetable garden.

The blooms of these beauties soar high in the air and wave orbs of color at the end of long, slender stalks. Most alliums bloom later than the spring bulbs so you can transition focal points of garden color to carry from daffodils to roses with the bold, brilliant allium.

There are over 700 species of ornamental onions to choose from. Some are tiny—only 6 inches high while others grow to be over five feet tall. Some have nodding, bell-shaped blossoms while others look like a explosion of fireworks.

The ‘Star of Persia” (Allium christophii) makes a spectacular softball sized  starburst of stars (try saying that 10 times fast) on 12 to 20 inch stems. Amethyst purple Purple Star of Persia plantflowers debut in late spring and often last for 2 to 3 weeks. The impressive three-foot-tall Allium Globemaster’s (Allium x ‘Globemaster’) eight inch blooms continual from late spring through early summer. My favorite giant flowering onion is Allium shubertii. The blooms look like living Fourth of July volleyball-sized fireworks in late spring to early summer, sitting on top of 1-2 foot stems. They have a fragrance that will surprise you and are a favorite with bees and other beneficial insects. They dry well too, so use them in cut flower arrangements to get even more enjoyment.

Most often, ornamental alliums bloom in rich pinks and purples, but some are white (A. neapolitanum), sky blue (A. caeruleum), and bright yellow (A. moly). Although most form globes of clustered flowers, others, such as A. siculum, A. triquetrum, and A. cernuum, have a dainty little relaxed, dangling blooms. The “bride’s onion” (Allium neapolitanum) can be a perennial in our zone, is drought-tolerant so it works well for xeriscaping, and even in containers.

These plants are in the onion family so, rodents, rabbits, and deer tend to leave them alone, deterred by their strong flavor. With a bit of strategy in your plant placement, they may help to protect other plants from being easy access for uninvited nibblers in your garden.

purple ornamental onionsGrowing ornamental onions is easy. All alliums like rich, well-drained soil and prefer a sunny site, although many species will tolerate shade. Plant the bulbs for all “standard sized” alliums 4 inches deep but set the bulbs for the giant varieties 8 inches deep—measured from the base of the bulb.

Choose varieties that are suited to our planting zone 7, keep them in the right place to reduce environmental stress and they will live long and prosper, multiplying enthusiastically! Plant alliums throughout the garden in groups to get the most color bang—standing alone won’t be as powerful. Achieve the best look by planting three to five bulbs spaced well apart for large alliums or a group of 10 to 15 for smaller species. When you are bulb shopping this fall consider adding a show stopping giant allium or a delicate-looking dwarf to your garden. You’ll be glad you did. For more information on various varieties take a look at https://plants.ces.ncsu.edu/plants/category/all/3/?.