Soil type: Alliums are best planted in well-drained soil but are quite tolerant of a range of conditions, provided the soil is not waterlogged. If you have heavy clay soil, add gravel to the planting holes.
Aspect & position: Choose a position in full sun for alliums, and if you are growing a very tall variety, a sheltered position is preferred to protect them from blowing over in the wind. Remember that alliums are very perennial, so choose a permanent position for them that will not be disturbed.
Dig a hole for each bulb, or if you’re planting lots at once, dig a trench. I usually plant in good drifts, rather than in twos and threes to avoid a spotted look.
On heavy soil, a 5 cm (2 in) layer of gravel (or use compost) is spread over the bottom of the hole or trench.
As a general rule, make sure the hole is at least twice as deep as the bulb, and leave a gap of at least 3 times the width of the bulb between each bulb. For small to medium sized bulbs (such as ‘Purple Sensation’) this is about 10-15cm (4-6in) deep and 10-15cm (4-6in) apart. For the larger varieties (like ‘Purple Rain’) it’s about 15cm (6in) deep, but at least 20-30cm (8in-1ft) apart as they need more room for their much larger flower heads and foliage. Giants like ‘Globemaster’ need to be spaced 30-45 cm (12-18 inches) apart to accommodate their gorgeous heads.
