How to Grow Alliums

Plant allium bulbs in a sunny position in autumn, ideally between September and November, to give them time to establish strong roots before winter. This time window is ideal, as cooler temperatures and autumn rains help bulbs develop strong root systems without triggering premature top growth. It also mirrors their natural growing cycle and ensures vigorous flowering the following spring.

For ‘Purple Sensation’ allium planting, we recommend early autumn (September-October) as ideal, as this popular variety benefits from a longer establishment period.

How to Grow Allium Bulbs: Planting Steps

• Plant bulbs three times their depth (e.g., 15cm deep for 5cm bulbs)
• Space 15-20cm apart; closer for dense displays
• Position pointed end up, flat basal plate down where roots emerge
• Plant structural plants in drifts of 5-7 bulbs for architectural interest in borders

Planting Allium Bulbs in Pots

Alliums thrive beautifully in containers, making them perfect for patio spaces or balconies. Use 30cm diameter containers with drainage holes and fill with 50:50 peat-free compost and horticultural grit. Plant at the same depth as borders. Water sparingly over winter, increasing as growth appears.

When Do Alliums Flower?

Alliums flower from late spring through early summer, with most ornamental alliums blooming between May and July, with the flowering season typically lasting 2-3 weeks.

Early bloomers like 'Purple Sensation' flower in May and June, mid-season varieties such as Allium sphaerocephalon appear in June, and late bloomers, including Allium caeruleum, extend the display into July. By selecting varieties with staggered bloom times, you can enjoy continuous allium flowers from May through July.

Popular Varieties

Purple Sensation
Height: 75–90cm
Bloom time: May to June

Allium caeruleum
Height: 30–60cm
Bloom time: June to July

Allium sphaerocephalon
Height: 60–90cm
Bloom time: June

Allium giganteum
Height: 1.2 metres
Bloom time: May to June

Allium atropurpureum
Height: 60–90cm
Bloom time: May to June