How To Grow Allium Bulbs

Alliums have distinguishable pom-pom flowers which bloom for weeks and are loved by bees. They typically come in shades of purple, pink and white, and look great planted in clusters, in grass and in borders, as well as making excellent cut flowers.

Read this guide on how to grow allium bulbs for the best chance of having beautiful, blooming alliums in May/June.

Selecting Alliums Choosing the right allium bulbs is the first step. There are many different alliums available so it is important to do your research before buying bulbs, to ensure they will fit in and thrive in your garden or planter.

When selecting your allium bulbs, you should consider the following:

● Height - different alliums grow to different heights, with some growing to 90cm or taller, such as Summer Drummer alliums

● Flower head size - flower heads can vary from just 2cm to 20cm in diameter

● Flowering time - most alliums flower in May and June, but some flower later, in July and August, such as Globemaster alliums

● Garden conditions - different alliums are better suited to different conditions or environments

● Colour - alliums are available in a range of blues, purples, pinks, whites, and yellows

Take a look at the range of allium bulbs available to get a good idea of the species that are available and their individual characteristics to help you determine which would be best suited to you and your gardening project.

Planting Alliums

Most allium bulbs should be planted in autumn, between September and December. For best results, they should be planted in moist but well-drained soil, in a spot that gets plenty of sun but is sheltered from the wind, to help prevent the stems from being blown over.

Bulbs can rot if planted in shaded areas prone to cold or in waterlogged soil, so you must avoid planting in these conditions.

The leaves of alliums die down at flowering time. Plant alliums among other plants, such as low-growing herbaceous plants, so that any unsightly foliage after flowering is well hidden.

Before planting, dig over the soil and remove any weeds. Avoid planting in soil which has been freshly manured as it is likely to be too nutrient rich.

Plant allium bulbs four times deeper than the diameter of the bulbs. For example, if a bulb is 4cm wide, plant it at a depth of 16cm. Bulbs of smaller alliums should be planted 7.5-10cm apart, whereas alliums which grow bigger or taller should be planted at least 20cm apart.

If you are planting allium bulbs in containers, opt for deeper pots with drainage holes, and use a peat-free general purpose potting compost.

Caring For Alliums

You do not typically need to water alliums that are grown in the ground, but alliums grown in containers will need to be watered regularly. However, you need to make sure that the compost does not become waterlogged.

Annually apply a mulch to the surface of your soil, using manure or well-rotted compost to conserve moisture, improve the condition of the soil, and reduce weed growth. If you have poor soil then apply a balanced fertiliser in spring, otherwise, regular feeding is not necessary.

Deadheading is not essential when it comes to alliums, but you can cut off any spent flower heads at the base if you wish.

For help selecting the best allium bulbs for your gardening project, contact our knowledgeable team at Boston Bulbs on 01775 769333, or email We have a wide range of allium bulbs available, with options to suit both novice and avid gardeners.

The Boston Bulb Company has over 40 years of experience in supplying only the finest quality horticultural products from farmers and growers throughout the UK and Europe.

Share this post