Plant these ornamental onion bulbs a.s.a.p upon receipt in the garden or in flower pots/planters for on the patio/decking. The soil should be free-draining – add some sand to clay soil or potting compost. The lower growing varieties are of course the most suitable for window boxes and pots. Bulbs that are not planted need to be stored frost-free. Also potted bulbs are not generally hardy so will need protection.
Plant your bulbs in a hole three times as deep as the circumference of the bulb – a 5 cm bulb therefore goes in a 15 cm deep hole. The planting distance for large ornamental onions is about 25 cm, for allium molly (the smaller variety) only 5 cm apart. Loosen the soil and plant the bulbs with the tip up. Fill the hole and try not to walk over the soil. For larger swathes, dig a wider hole and plant several bulbs together. Ornamental onions grow best in fertile soil in full sun.

Allium sp. (ornamental onion) bulbs can remain planted in the same spot for years. Remove overblown flowers and their stems once they have turned brown, this will direct all energy back to the bulb, the food stored in the bulb helps for next year’s growth. Only cut back the leaves on your ornamental onion when they have turned yellow. With minimal care, the flowers will return year after year producing lots of flowers.
 

Alliums in the winter

Alliums planted in the garden are hardy - just be sure to avoid soil that is too wet (especially in the winter) as this will not be tolerated.
Potted alliums are somewhat more sensitive to frost so you will need to bring them into a frost-free area for the winter. As soon as frosts are over, get those pots outdoors again.

Tall ornamental onions look just fabulous at the back of beds or borders. The shorter varieties are ideal for planting at the front of the borders. The more you plant, the better the effect from the lovely blooms. Plant large alliums in groups of five among lower growing perennials in the border or scatter say 10-20 bulbs evenly over the border. The low-growing ornamental onions are best planted in larger groups. All alliums can be planted in pots (large bulbs = tall flower stems are best in large planters). Alliums mix wonderfully with summer flowering and leafy plants like hostas, lilies and roses.