How to plant and grow Alliums

Majestic Alliums for statement borders or pots

Alliums really do make a bold statement in the later spring/early summer months. Alliums need planting in the Autumn for flowering May/June. They are incredibly long lived and come back year after year. Alliums add strong colour and bold structure to your borders or pots. Plant in mass groupings for a greater impact or intersperse amongst other spring flowers and shrubs to fill the gaps.

Planting Alliums in the garden

Alliums like to receive a good amount of sunlight throughout the day otherwise they will start to lean to find the light. Find a position in your garden with full sun and well-drained soil. As with all bulbs, they don’t like to have wet feet so add horticultural grit to the base of the hole if necessary.

Once you have found the perfect spot in your garden to grow your Alliums, you need to dig holes in the flower bed that are three times the diameter of the bulb. For example, if the bulb is 5cm (2″) in size then it needs to be planted 15cm (6″) deep. If you find you have heavy soil, add a 5cm (2″) layer of horticultural grit to the base. You can also mix in the grit with the soil to cover the bulb to improve the drainage. Mix 1/3 grit to 2/3 soil. Space your allium bulbs about 20-30cm (8-12″) apart. For impact, plant in groups.

As with most bulbs, you can add a potash feed to enhance the growth and strengthen the bulb. This will encourage the bulbs to flower year on year.

Planting Alliums in pots

Plant Alliums the same depth for pots as in the garden. Plant three times the diameter of the bulb. For example, if the bulb is 5cm (2″) in size then it needs to be planted 15cm (6″) deep.

For a garden with limited space, you may want to produce a fuller display of spring flowers by layering your bulbs like a lasagne. Simply plant your bulbs deeper to start with, with the largest or latest flowering bulbs further down, moving to the smallest and earliest flowering in the top layer. The shoots from the lower bulbs will find their way around the other bulbs. If you are planting the Alliums first, allow 10cm (4″) of soil underneath the bulbs. Add horticultural grit to heavy soil to improve water drainage. Ensure to plant your Allium bulbs with the pointy end up. Water the bulb well once in situ.

Caring for your Alliums

  • Cut the Alliums back at the end of their blooming season. They will then continue to grow in your garden year on year with very little maintenance and remove any dead foliage in early Summer.
  • Once the stem has turned brown and hollow, remove any dead stems. They can easily be detached from their bases by hand.
  • Alliums are hardy and can therefore be left in the ground all year round.
  • Keep an eye out for any diseased foliage.
  • Seldom need support.