Common name: Flowering Garlic
The allium family contains around four hundred species some of which includes the familiar onion, garlic and chives.
Allium aflatunense also known as ornamental onions, are grown for their showy flower heads that come in a wide range of colour and sizes.
Depending upon variety plants can grow to a height of 300mm-1200mm (12"-48") high.
The star like 25-150mm (1"-6") diameter flower heads in either blue, purple, white or yellow appear in June.
Alliums look at their best if the bulbs are planted out in groups of three or more set at 200mm (8") apart.
The smaller varieties such as Allium sphaerocephalon can be closely planted for impact.
When the plants die back, the dried flower heads look quite attractive if left in the garden, alternatively; they can be cut for indoor flower arrangements.
Plants prefer a sunny, sheltered spot, in a light moderately fertile well drained soil in full sun, although some varieties will tolerate dappled shade.
They will not tolerate cold,exposed or waterlogged areas.
If and when they are grown in heavier soils, provide a layer of horticultural grit ito the base of the planting holes to improve drainage.
For stability, bury them three to four times their own depth, or a minimum of 75mm (3") deep whichever the greater.
Allium sphaerocephalon produces relatively small heads in relation to its height, which is normally around 500mm (18") high.
It also produces more than one flower head per plant,unlike the variety aflatunense, which only produces one flower head per plant.
Bunch of sphaerocephalon
The smallness of the heads is thought to be the reason for it is sometimes to be referred to as 'The Drumstick' allium.
This plant has the potential to become invasive due to the small 'bulblets' that often grow under the flower head.
All types of allium can be left undisturbed until the clumps become overcrowded, then they should be lifted, split, and replanted immediately.
After flowering, the leaves should be allowed to die back, and not removed until completely brown.
If space is at a premium you could consider growing alliums in deep outdoor containers.
Although the choice is yours, it is probably best to use lower growing varieties when growing in containers.
Pests & Diseases:
As mentioned above Alliums are closely related to culinary onions, and may occasionally suffer from related problems, such as white rot, downy mildew and onion fly.
Therefore it is advisable not to plant them in a spot where onions have been grown in previous years.
Sow commercially purchased seed in trays of seed compost and germinates at a minimum temperature of 16°C (60°F)
Germination should take 2-3 weeks.
Prick out seedlings sown the previous year (circa week 27) into 70mm (3") pots and place in a cold frame until ready for planting out.
Prick out seedlings if large enough to handle into 70mm (3") pots and place in a cold frame until ready for planting out the following year.
It can take two or three year to get to flowering stage.
circa week 18:
As new growth appears; top dress the border/bed with a general fertilser to the manufacturers specification.
Collect seed after ripening and sow them immediatly in pots in a cool greenhouse or coldframe to produce flowering bulbs.
Alternatively, store the seeds in a fridge and sow them in spring at about 13°C (55°F).
Sow the collected seeds thinly and grow on for a year, then prick them out into pots/boxes or nursery bed and grow on for at least one more year.
Seeds should germinate within 10-12 weeks.
Being hybrids they may not necessarily come true to the parent plant from this method, plus they will take several years to reach flowering size.
Some alliums e.g. Allium sphaerocephalon often produce aerial bulbils in the flower head.
These should be carefully removed, separated, and either placed 25mm (1") apart and 10-12 mm (½")deep in a nursery bed or in pots of gritty compost and grown on in a coldframe.
They then can be treated as described under seed sown varieties.
Plant out; in well prepared fertile soil,covering the bulbs to three or four times their own depth, min 75mm(3"), and leave untouched for several years.
Plants may need staking, especially on exposed sites.
If required; from now and until March divide large clumps and replant immediately.
Many species produce offsets, these should be detached and planted out immediately.
Smaller offsets can be placed in pots of gritty compost and grown on in a coldframe until planting out time the following year.