Alliums, also known as ornamental onions, are a striking addition to any garden border. Their globe-shaped flower heads and late spring to early summer bloom time make them a favorite for gardeners seeking both structure and color. If you’re considering adding Allium to your garden, here’s what to keep in mind when choosing and buying bulbs.

When to Buy Allium Bulbs?

Allium bulbs are typically available for purchase from late summer through autumn. The best time to buy is between August and October, as this ensures you have the widest selection and the bulbs are fresh. Planting is done in autumn, before the first hard frost, so the bulbs can establish roots before winter.

How to Recognize Quality: What to Look For

When selecting Allium bulbs, check that they are firm and heavy for their size. The outer skin should be dry and intact, without signs of mold, soft spots, or damage. Avoid bulbs that feel light, shriveled, or have visible rot. Larger bulbs generally produce stronger, larger flower heads, but smaller bulbs can also give good results, especially for naturalizing.

Which Varieties Suit Your Garden?

Alliums come in a range of heights, colors, and bloom times. For dramatic effect in borders, consider tall varieties like Allium 'Globemaster' or Allium 'Purple Sensation'. For smaller spaces or pots, look for compact types such as Allium christophii or Allium karataviense. Think about your border’s color scheme and flowering period—mixing several types can extend the Allium season from late spring into early summer.

Combining Allium with Other Bulbs

Alliums combine beautifully with other spring-flowering bulbs and perennials. Their upright stems and spherical blooms add height and contrast among tulips, camassias, or ornamental grasses. When planting, group bulbs in odd numbers for a natural look and stagger heights for layered interest.

Introgreen Selection: Current Allium Bulbs