How to Plant Allium Bulbs: Step-by-Step Guide

What is an Allium?

Alliums, part of a genus that includes onions, garlic, and scallions, are valued for their ornamental and edible qualities. Known for their tall stature and globe-shaped blooms, they add interest to gardens during late spring to early summer. These flowers, which come in shades like white and violet, attract pollinators such as bees and hummingbirds. Easy to grow in various soil conditions, alliums continue to provide aesthetic value even after blooming, making them excellent for cut and dried arrangements. Additionally, their distastefulness to animals helps protect them from being eaten, while their ability to naturalize enhances their garden presence each year.

Where to Plant Allium Bulbs

Alliums fit into almost any garden setting! Thanks to their in-between-seasons bloom time, these bulbs provide a much-needed bridge of color between spring and summer flowers. Alliums naturalize beautifully and can make amazing back-of-the-border flowers due to their stance and shape. One of our favorite benefits of growing alliums? An allium field is truly a pollinator's paradise.

Alliums really look best in the company of other summer bloomers. Sweet alyssum, rock cress, bachelor's buttons, coreopsis, sweet William, foxglove, baby's breath, daylily, iris, red hot poker, coralberry, barberry, Japanese Maple, Deutzia rosea, weigela, and Geranium pretense are just some of the companion plants that look fantastic with Alliums.

Alliums do best in full sun with well drained, fertile soil and good moisture. Choose a location that receives at least six to eight hours of sunlight per day, and where water does not pool. These are great plants for xeriscaping, as they grow deep roots and don't mind bright sunlight.

Alliums can be grown in containers, but keep in mind that most alliums require a good bit of planting depth. If you're planting a taller allium, make sure to provide at least 8 to 10 inches of soil, and plenty of space for the plant to grow tall. Alliums don't have a wide spread, so they can be planted fairly close together.

When to Plant Allium Bulbs

Alliums are best planted in fall, usually in September or October, depending on your garden zone. Wait until after the first frost, but get your bulbs into the ground before the soil is completely frozen. By waiting until cooler weather to plant your alliums, you'll reduce the risk that they'll sprout too early and experience frost damage. These bulbs need enough time to establish a little rooting before the deep cold of winter. Alliums bloom in late spring or early summer.

How to Plant Allium Bulbs

Now that we've determined where and when to plant alliums, let's get to planting. Alliums are extremely easy-care bulbs right from the start, and planting alliums is a breeze. Let's look at how to do it.

• Work your soil. Use a hoe or spade to break up the soil in your planting location, and mix in compost, peat moss, or another drainage-improving material if you find that your soil is compacted or clay-heavy. Break up your soil to at least a foot of depth, so that your alliums' roots aren't fighting through hard, rough soil.
• Determine spacing. Most alliums require just four to eight inches of space for each bulb—alliums don't have a wide footprint and can be planted relatively close together. However, they do need a bit of breathing room to become properly rooted.
• Plant your allium! A good rule of thumb is to plant about two to three times the height of the bulb. Because allium varies so greatly by species, your planting depth depends upon variety. A small one-inch-tall bulb will be best planted around 3 inches deep, while a giant three-inch-tall bulb could be planted up to 6 inches deep. Dig individual holes using a spade and backfill carefully. Remember that your bulbs should be point-up!
• Water in your alliums well. You won't need to water again over the winter, but begin watering regularly once the plants sprout in spring. In general, your alliums' soil should be moist, but not soggy, to the touch. If you experience a dry spring, you may need to water weekly.

Now you just need to sit back and wait for spring to arrive!

Caring for Alliums

After your alliums have bloomed, wait until the leaves die back on their own before cutting them back. Alliums, properly cared for, will come back year after year. Allium bulbs do not need to be lifted in the fall.

How Deep to Plant Allium Bulbs

Giant allium bulbs should be planted about 6 inches deep while small allium bulbs should be planted about 3 inches deep.

Do Alliums Multiply

Yes, alliums have the ability to naturalize exceptionally well by multiplying year after year for increased beauty.

What are Common Allium Pests and Diseases?

Aside from the occasional snail and slug, alliums are, for the most part, pest and disease-free. In fact, the scent of these bulbs is actually a deterrent for deer and rodents. The presence of allium can actually protect your other bulbs from damage!

Should you find holes in your alliums' leaves, the most common perpetrator is a slug or snail. Use diatomaceous earth, beer traps, or slug bait to relieve your garden of those pests. Garden pest spray for ornamentals can also help eliminate aphids, earwigs, and other pests.

What are Popular Allium Varieties?

Alliums are available in a wide variety of shapes and sizes. Here are a few of our favorite garden-worthy allium varieties. Mix and match to create an all-allium garden, or choose the colors and heights that coordinate with other perennials and bulbs.

• Red Giant Allium lives up to its name in every way! Blooming in a deep magenta color with flowers nearly five inches across, this allium stands just 12 inches tall. The combination of large flowers and short stems is particularly charming in a cottage garden.
• Clusters of star-shaped purple-blue florets appear in large form on the Persian Blue Allium. Great for a cool-tone garden, Persian Blue stands out from the purple crowd.
• Graceful Beauty Allium offers large white florets with centers of purple. This allium features shining white petals in high-visibility form. A unique allium!
• A classic Drumstick Allium adds height and whimsy to the garden, with small flowers on stems 20 to 24 inches tall. These compact flowers bloom in a deep purple tone.
• Schubertii Allium stands out as a somewhat "exploded" allium. This unusual plant features nearly 100 individual purple florets on 16-18" stems that radiate from a ball-shaped center.
• For the pink-loving gardener, Rosy Dream Allium features a classic allium shape in a rosy-purple hue. Three-inch wide blooms stand out in the garden and in the vase.

Alliums come in all shapes and sizes and are lots of fun to grow! These easy plants sparkle in disco-ball form in neat rows or informal cottage gardens. There's an allium for everyone.