Though related to the edible members of the genus Allium that are likely to appear frequently on your dinner table—onions, leeks, garlic, shallots, and chives—ornamental alliums are very different. These perennials have a lot to offer as additions to your spring and fall garden. The colorful balls of blooms consist of numerous smaller flowers and create Dr. Seuss-like displays of lollipops throughout the garden.

Because these bulbs have relatively unobtrusive foliage that blends in quite well with surrounding plants, they are easy to mix and mingle with other plants in the garden. The hardiness varies with the species and cultivar, most alliums are hardy in zones 4-9. The plants are easily recognized by their big, round heads of flowers, though some types may be less showy than others.

Where to Plant Allium

For the most blooms, plant alliums in full sun. This will ensure 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.

Alliums do well in gravel gardens and dwarf varieties are suitable for growing in troughs and small containers.

Surround plants that tend to get browsed by deer and other animals with alliums, as their scent and taste deter wildlife.

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. Water well.

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 sun.

Soil and Water

Because alliums generally form bulbs, they need well-drained soil. Rich, sandy loam is ideal. If their bulbs sit in water, they'll rot. In terms of soil pH, neutral to slightly acidic (5.6 to 6.5) is best.

The fact that most alliums are bulbs works to their advantage. By storing water and nutrients, these plants are extremely drought tolerant and 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. During dry spells, water every three to five days.

Temperature and Humidity

When you choose allium plants, check their hardiness in your zone. Most types are hardy in zones 4-10 and bloom before the hottest part of summer, so they 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, alliums typically don't need fertilizer.

Pruning

When allium has finished blooming, removing spent blooms encourages the plants to store more energy for next year's show, but it isn't necessary. Leaving the old flowers on adds 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

Plant allium in pots with large drainage holes and use well-draining potting soil. Remember that potted plants dry out much faster than plants in garden soil so adjust the watering schedule accordingly.

Despite the cold-hardiness of alliums, growing them in pots requires special winter protection because in containers, unlike in garden soil, the bulbs are exposed to temperature fluctuations and cycles of freezing and thawing, regardless of the size of the container. It is best to bury the pot in the ground in the fall for insulation and dig it out when the weather warms up in the spring.

Allium grown in a pot will need repotting as it outgrows its container.

Pests and Problems

There are very few pests or problems with alliums. Because allium is a member of the onion family, its blooms have the typical pungent odor. This smell works as an animal deterrent and, coupled with their taste, prevents allium bulbs from being eaten by 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 is prone to fungal diseases such as rot and downy mildew, but these issues are easily avoided. Never water from overhead and remove any infected bulbs as soon as you notice them.

How to Propagate Allium

Alliums are easy to propagate by division. The bulbs start to multiply after a couple of years so it's a good idea to refresh a clump after 3 to 4 years. Dig the plant up in the 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 regions with milder winters, sow allium seeds in the late summer, fall, or early winter.

Types of Allium

The flowers of alliums vary greatly, Some allium varieties have flat-topped or domed blooms that add a nice geometry to garden designs. Other varieties still have more explosive blooms reminiscent of fireworks throughout the garden.

Keeled Garlic

Allium carinatum pulchellum blooms in late spring, showing off clusters of nodding reddish-purple flowers on 2-foot-tall stems. Zone 5-8

Allium schubertii

Allium schubertii is one of the most dramatic alliums. It shows off volleyball-size clusters of lavender flowers on 2-foot-tall stems. Zone 4-10

Giant Allium

Allium giganteum is one of the largest allium varieties. It bears large globe-shaped clusters of purple flowers on 6-foot-tall stems. Zone 5-10

'Gladiator' Allium

The stalks of this hybrid allium grow a towering 4 to 5 feet tall with softball-size purple blooms in early summer. Zone 4-7

'Globemaster' Allium

The hybrid allium 'Globemaster' is a dramatic selection with 10-inch violet flower heads on 3-foot-tall stems in late spring to early summer. Zone 4-9

Naples Garlic

Allium neapolitanum is a summer-blooming species that has 2-inch-wide clusters of white flowers. It grows 16 inches tall. Zone 6-10

Nodding Onion

Allium cernuum is a North American native with clusters of pink flowers in summer on 2-foot-tall stems. Zone 4-10

Showy Allium

Allium rosenbachianum offers 4-inch-wide globes of purple flowers in summer. It grows 3 feet tall. Zones 4-10

Star of Persia

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

Companion Plants for Allium

Cabbage

Cabbage attracts many pests but allium makes an excellent companion plant for cabbage. The scent and taste of allium repel animals. Allium keeps cabbage loopers and other vegetable-eating insects away from plants.

Phlox

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. Zone 3-8

Yarrow

Yarrow is a classic garden perennial known for its ruggedness. It shrugs off cold winters, hot and humid summers, drought, and poor soils to cheerfully bloom in sunny places. With its tall stems of colorful flowers and fern-like foliage, it works especially well in a cottage garden setting and in wildflower gardens. Zone 3-10

Garden Plans for Allium

Summer-Blooming Front-Yard Cottage Garden Plan

Create charm and curb appeal in your front yard with this lush, beautiful cottage garden plan.

Soften a Fence with This Lush Border Garden Plan

Backyard fences are functional, but not always the prettiest thing to look at. This garden plan draws attention away from the harsh lines of fence posts and slats with plants that provide long-lasting color, fragrance, and texture.

Beginner Garden for Full Sun

This easy-care, sun-loving design is a great introduction to perennial gardening. The collection of plants in this garden plan will provide you with colorful blooms from spring to fall.