Gardening Flowers Bulbs How to Plant and Grow Allium Learn to grow blooms that look like they were plucked right out of a Dr. Seuss book. By Hollyanna McCollom Hollyanna McCollom Hollyanna McCollom is a writer and editor with more than 15 years of experience. As a freelance writer, she specializes in food, pop culture, wellness, DIY craft, and sustainable living. She is the author of the Moon Portland travel guide (now in its 4th edition) and previously served as editor-in-chief of PDX Magazine, as well as the editorial lead for several other small publications and projects. Learn about BHG's Editorial Process Updated on October 4, 2023 In This Article View All In This Article Where to Plant Planting Tips Care Pests and Problems Propagation Types Companion Plants Garden Plans FAQ You are probably familiar with the members of the genus Allium that are likely to end up on your dinner table—onions, leeks, garlic, and shallots. But their prettier cousins, the ornamental alliums, have a lot to offer as additions to your spring and fall garden. Because the perennial plant allium has relatively unobtrusive foliage that blends in quite well with surrounding plants, they're easy to mix and mingle with other plants in the garden. Depending on the species and cultivar, they're hardy in zones 4-9. Allium is easily recognized by its big, round head of flowers, though some types may be less showy than others. Mark Kane. Their oniony smell is a powerful deterrent to most hungry animals, but allium is nonetheless considered toxic to dogs, cats, and horses. Some species, like Allium giganteum (or giant allium), are also toxic to humans. Allium Overview Genus Name Allium Common Name Allium Plant Type Perennial Light Part Sun, Sun Height 6 to 12 inches Width 6 to 12 inches Flower Color Blue, Pink, Purple, Red, White, Yellow Foliage Color Blue/Green Season Features Fall Bloom, Spring Bloom, Summer Bloom Special Features Attracts Birds, Cut Flowers, Good for Containers, Low Maintenance Zones 4, 5, 6, 7, 8, 9 Propagation Division, Seed Problem Solvers Deer Resistant, Drought Tolerant Where to Plant Allium For the most productive display of blooms, plant alliums in full sun. This will assure sturdy stems, so flowers will be less likely to flop. Giant varieties may benefit by being planted near a wall or fence for some protection from strong winds, so you won't have to worry about your blooms snapping in a storm. Some varieties tolerate part shade but perform best in full sun. Avoid soggy soil or locations that don't drain well. Their scent and taste can deter deer and other animals, so try planting some at the front of garden borders or surrounding tender lily bulbs. How and When to Plant Allium Plant allium bulbs in the fall for late spring or early summer blooms. Plant them about 12 inches apart at a depth of 2 to 3 times the diameter of the bulb and water well. Alliums make great additions to gravel gardens, and dwarf varieties also make great accents in troughs and small containers. Allium Care Tips Very little maintenance is required for allium to grow and thrive. Light Get as much growth and as many flowers out of your allium during their short season by planting them in full sunlight. Soil and Water Because alliums generally form bulbs, they need well-drained soils. If their bulbs sit in water, they'll rot. The fact that most alliums are bulbs works to their advantage. By storing water and nutrients, these plants are extremely drought tolerant and can survive long dry spells that might kill other plants without the benefit of a storage root. If you get plenty of rain (about an inch per week), there's no need to water allium—if you don't, water every three to five days. Temperature and Humidity When you choose allium plants, check their hardiness in your zone. Most are hardy in zones 4-10 and bloom before the hottest part of summer, so will do fine in a range of temperatures. Fertilizer Add balanced fertilizer when your plants first start flowering. For the amount to use, follow product label directions. Otherwise, they don't need fertilizer in most soil. Pruning When allium has finished blooming, removing spent blooms can encourage the plants to store more energy for next year's show, but it isn't necessary. Leaving the old flowers on can add interest as they dry (they look like miniature fireworks) and encourage reseeding if you're hoping to increase the number of allium plants in your garden. Potting and Repotting Allium Allium grown in a pot will need repotting as it outgrows its container. In autumn, dig out the bulbs of the plant and divide where needed. Replant in pots that are well-draining, or add divided bulbs to in-ground gardens before the first frost. Pests and Problems There are very few pests or problems with alliums. Because alliums belong to the onion clan, these blooms are associated with that trademark odor. This smell works as an animal deterrent and, coupled with their taste, prevents alliums from being eaten by creatures like pesky rabbits, deer, and other browsing animals. Many gardeners take advantage of this and plant them among other plants to act as a barrier to troublesome critters. Alliums can develop fungal diseases like rot and downy mildew, but these issues are easily avoided. To prevent rot and mildew, avoid overhead watering and remove any infected bulbs as soon as you notice them. How to Propagate Allium Alliums don't require dividing annually, so there's no need to dig them up every fall. The bulbs start to multiply after a couple of years so it's a good idea to refresh a clump after 3-4 years. Dig the plant up in fall and separate the bulbs along the visible division lines. Replant a new healthy bulb in the original space and plant the remainder in other areas of your garden. To grow allium from seed, start them indoors to speed up the germination process and—depending on the species—be prepared to wait as long as a year before you see blooms develop on your new plants. You can also sow seeds directly into your garden in the spring when the seeds are unlikely to be washed out by heavy rains. In some regions with milder winters, you can sow allium seeds in the late summer, fall, or early winter. Types of Allium The variety of allium colors, shapes, and sizes makes them easy to use. The colorful balls of blooms are composed of numerous smaller flowers to create Dr. Seuss-like displays of lollipops throughout the garden. There are also many allium varieties that have flat-topped or domed blooms that can add a nice geometry to garden designs. Other varieties still have more explosive blooms reminiscent of fireworks throughout the garden. Allium aflatunense Mark Kane Allium aflatunense features big, spiky flower heads packed with purple blossoms on thick stems in late spring. It grows 30 inches tall. Zones 4-8 Allium carinatum pulchellum Denny Schrock Allium carinatum pulchellum blooms in late spring, showing off clusters of nodding reddish-purple flowers on 2-foot-tall stems. Zones 5-8 Allium cyathophorum var. farreri Denny Schrock Allium cyathophorum var. farreri is a vigorous selection with clusters of deep violet-purple flowers in summer. It grows 1 foot tall. Zones 4-9 Allium schoenoprasum Marty Baldwin More commonly known as chives, this traditional herb is grown more for its tasty foliage than its purple blooms. Zones 4-8 Allium schubertii Andy Lyons Allium schubertii is one of the most dramatic alliums. It shows off volleyball-size clusters of lavender flowers on 2-foot-tall stems. Zones 4-10 Allium oreophilum Mark Kane Allium oreophilum is a tiny star for the rock garden. This petite onion features airy clusters of rosy flowers on 4-inch plants. Zones 4-7 Allium senescens subsp. montanum var. glaucum Denny Schrock Allium senescens subsp. montanum var. glaucum is perfect for the rock garden or front of the border. It has blue-green leaves that grow in a spiral and clusters of purple-pink flowers in late summer. It grows 6 inches tall. Zones 5-9 Allium stipitatum Dean Schoeppner Allium stipitatum blooms in early summer with 4-inch-wide clusters of lilac flowers. It grows 4 feet tall and is sometimes confused with the similar showy allium. Zones 4-9 Allium tuberosum Denny Schrock Another tasty allium, garlic chives are not quite as commonly used as standard chives. These have a flat leaf blade, where standard chives are hollow tubes. White blooms are borne in early summer. Zones 4-8 Allium triquetrum Peter Krumhardt Allium triquetrum bears clusters of drooping white bells that flourish in partial shade and will spread in moist soils. The flowers unfurl in late spring on 18-inch-tall stems. Zones 3-9 Giant allium Elvin Mcdonald Allium giganteum is one of the largest varieties. It bears large globe-shaped clusters of purple flowers on 6-foot-tall stems. Zones 5-10 Bear's garlic Peter Krumhardt Allium ursinum is noted for its 2-inch-wide shaggy white flower heads that appear on 18-inch-tall stems in summer. Zones 4-9 Blue allium Bill Stites Allium caeruleum delights with airy bunches of delphinium-blue flowers on 18-inch-tall stems in late spring. Zones 5-7 Drumstick allium Janet Mesic Mackie Allium sphaerocephalon offers egg-shaped reddish-purple spheres in early summer on 2-foot-tall stems. Zones 5-9 'Gladiator' allium Blaine Moats Huge stalks reaching 4-5 feet tall are topped with softball-size purple blooms in early summer. Zones 4-7 'Globemaster' allium Peter Krumhardt Allium 'Globemaster' is a dramatic selection with 10-inch violet flower heads on 3-foot-tall stems in late spring to early summer. Zones 4-9 Golden garlic Mark Kane Allium moly produces bunches of star-shaped, bright yellow blooms that spread their sunshine in rock gardens in late spring to early summer. It grows 12 inches tall. Zones 3-8 'Hair' allium Andy Lyons Allium 'Hair' is the most unique allium. Rather than petals, this plant bears spidery green leaves atop its 18-inch-tall stems in late spring. Zones 4-8 'Ivory Queen' allium Marty Baldwin Allium karativiense 'Ivory Queen' shows off 6-inch orbs of white flowers over wide, blue-green foliage. It grows 10 inches tall. Zones 5-8 'Millenium' allium Blaine Moats Allium 'Millenium' features 2-inch-wide lavender-rose flower spheres above clumping green foliage for several weeks in late summer. It grows 12 inches tall. Zones 5-8 'Mount Everest' allium Andy Lyons Allium 'Mount Everest' bears tennis-ball-size white flowers on 4-foot leafy stems. Zones 4-9 Naples garlic Scott Little Allium neapolitanum is a summer-blooming species that has 2-inch-wide clusters of white flowers. It grows 16 inches tall. Zones 6-10 Nodding onion Elsa Bakalar Allium cernuum is a North American native with clusters of pink flowers in summer on 2-foot-tall stems. Zones 4-10 'Purple Sensation' allium Greg Ryan Allium aflatunense 'Purple Sensation' bears giant violet flower globes that radiate whimsy and cheer on 3-foot-tall stems in spring. Zones 4-8 Showy allium Peter Krumhardt Allium rosenbachianum offers 4-inch-wide globes of purple flowers in summer. It grows 3 feet tall. Zones 4-10 'Silver Spring' allium Denny Schrock Allium 'Silver Spring' bears clusters of white flowers marked with a red-purple eye. This dramatic selection blooms in early summer and grows 2 feet tall. Zones 4-8 Star-of-Persia Bryan E. McCay Allium cristophii bears distinct silvery-lavender flower globes measuring 12 inches in diameter atop tall 2-1/2-foot stems in late spring. Zones 4-9 'Summer Beauty' allium Denny Schrock Allium tanguticum 'Summer Beauty' shows off clusters of dark lavender-blue flowers in midsummer on 2-foot-tall stems. Zones 4-9 'Summer Skies' allium Dean Schoeppner Allium tanguticum 'Summer Skies' bears lavender-blue flowers in midsummer on 2-foot-tall stems. Zones 4-9 Turkestan onion Mark Kane Allium karataviense bears loosely clustered red-and-white flowers on 10-inch-tall stems in late spring. Zones 4-8 White giant allium Marty Baldwin Allium giganteum 'Album' is a white-flowering version of giant allium. It grows 6 feet tall. Zones 5-10 Companion Plants for Allium Cabbage Jay Wilde Plant allium with vegetables, like cabbage, to keep critters from eating your plants. The scent and taste of allium repel animals. Allium keeps cabbage loopers and other vegetable-eating insects away from plants. Phlox Jay Wilde. Phlox, whether tall or low-growing varieties such as sweet william, have the same soil and sun requirements as allium, and their smaller flowers complement the large allium pom poms. Yarrow Tim Murphy. This rugged perennial works in both cottage and wildflower settings. Garden Plans for Allium Summer-Blooming Front-Yard Cottage Garden Plan Illustration by Mavis Augustine Torke Create charm and curb appeal in your front yard with this lush, beautiful cottage garden plan. Download this garden plan Soften a Fence with This Lush Border Garden Plan Illustration by Mavis Augustine Torke The exciting plants included in this design will provide long-lasting color, fragrance, and texture. Download this plan now Beginner Garden for Full Sun Illustration by Mavis Augustine Torke This easy-care, sun-loving design is a great introduction to perennial gardening. Download this garden plan Frequently Asked Questions How big does allium get? The largest allium, Allium Giganteum, typically grows to be 3 to 5 feet tall (but can grow as tall as 6 feet). It produces softball-sized blooms that are approximately 5 to 6 inches in diameter. Is allium a perennial or an annual? Alliums are perennial plants and—if they are planted in a hospitable environment—they should return each year. With proper care, most alliums will live 3 to 4 years but can spread on their own if not moved or divided. Are allium invasive? Since most alliums can self-seed, some species can become invasive—especially in mild climates. Watch out for wild allium (A. ursinum) as well as wild garlic (A. vineale) in particular. Left unattended, they can form a dense carpet of growth and choke out other plants. Deadhead blooms before they go to seed to prevent unwanted growth. Was this page helpful? Thanks for your feedback! Tell us why! Other Submit Sources Better Homes & Gardens is committed to using high-quality, reputable sources—including peer-reviewed studies—to support the facts in our articles. Read about our editorial policies and standards to learn more about how we fact check our content for accuracy. Onion. ASPCA. (n.d.). Allium giganteum. Allium giganteum (Giant Ornamental Onion, Ornamental Onion). North Carolina Extension Gardener Plant Toolbox.(n.d.). Allium ursinum - plant finder. Missouri Botanical Garden. (n.d.).