How to plant Allium bulbs


Alliums bridge the gap between spring and summer when your garden is short on colour. Even if it weren’t for this nifty trick, you’d still want to grow them. The strikingly geo-metrical flowerheads and often intense colours of Alliums ensure that they make a bold statement in any garden. Strange though it may seem, they are actually relatives of onion and garlic, but there’s nothing oniony about the sweet scent most varieties’ flowers give off. Allium varieties range from smallish, cute, and colourful plants to tall-stemmed, large-flowered stunners.

Allium planting basics

Alliums will flower much later than most of your spring flowering bulbs, but that’s to your advantage. Step one is to choose a sunny spot. Although they’re un-fussy and easy to grow, getting Alliums off to the best start possible pays off. Compost is perfect for improving almost any soil’s texture and structure, if you have a heavy or very light soil, start by digging plenty of compost in to improve the structure and nutrients.

Allium planting instructions

— Alliums are fully hardy and will be happy outdoors throughout winter. They should be planted between September and December for best results. If you’re not ready to plant them as soon as you receive them, you can open up the packets to let air circulate the bulbs and store them in a cool, dry place. They should be stored no later than early December as they may start to deteriorate by that time, they won’t store until the following year.

— Allium bulbs can be planted directly outside in borders or patio containers. If you have a heavy soil or soil with a high clay content, it is a good idea to incorporate plenty of compost and some grit or sand prior to planting to aid drainage.

—If planting in containers, we recommend using peat-free multipurpose compost. Choose a position in full sun or very light partial shade.

— Allium bulbs come in a wide range of sizes, some are as small as peas and others are bigger than baseballs. The size of the bulb determines the planting depth, they should be planted around 1-2 times as deep as the bulb is high.

— Plant the bulbs with the pointed side facing upwards. Some allium bulbs will be flat on one side, this is normal.

— The size of the bulbs also determines the spacing between bulbs. Small bulbs can be scattered into wide, shallow holes—a spacing of around 5cm for small allium bulbs is fine. Large bulbs should be planted individually into holes and will need to be about twice the bulb width apart from each other.

— Cover back over with soil/compost. If the soil is very dry, it’s a good idea to water them in after planting to settle them. They will not require any further watering through winter unless you have very mild winters and the soil becomes dry. They will only require water in spring if it is warm and the soil is dry.

Plant calendar

  • Planting
  • Flowering

Gracy's tips: Alliums

"Plant your allium bulbs into groups of odd numbers—this will create a more dynamic and natural look in your garden. If the weather is particularly dry during the growing season, alliums will appreciate extra watering while in leaf."

Download instructions booklet

Planting instructions