One-Leaved Onion
Allium unifolium

Family: Alliaceae

What it is like

Allium unifolium is a BULB growing to 0.6 m (2ft) by 0.1 m (0ft 4in). See above for USDA hardiness. It is hardy to UK zone 8 and is not frost tender. It is in flower from June to July. The species is hermaphrodite (has both male and female organs) and is pollinated by Bees, insects. Suitable for: light (sandy) and medium (loamy) soils and prefers well-drained soil. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils. It cannot grow in the shade. It prefers dry or moist soil.

Height (m): 0.6

Where it is found

Moist soils in pine or mixed evergreen forest in the coastal ranges of California.

South-western N. America - California and Oregon.

Conservation Status:

Countries/locations it is found in

How it is used

Food

Rating: 3

Bulb - raw or cooked. The bulbs are 10 - 15mm in diameter. Together with the young shoots, they are fried and eaten. Leaves - raw or cooked. Flowers - raw. Used as a garnish on salads.

Root: includes bulbs, corms, tubers, rhizomes etc.

Medicine

Rating: 2

Although no specific mention of medicinal uses has been seen for this species, members of this genus are in general very healthy additions to the diet. They contain sulphur compounds (which give them their onion flavour) and when added to the diet on a regular basis they help reduce blood cholesterol levels, act as a tonic to the digestive system and also tonify the circulatory system.

Other

Rating:

The juice of the plant is used as a moth repellent. The whole plant is said to repel insects and moles.

Repellent: Plants that are said to deter but not necessarily kill various mammals, birds, insects etc.

How it is grown

Prefers a hot dry sunny position in a light, rich well-drained soil. This species is difficult to maintain under cultivation in Britain, our weather is probably too wet and cool for it to really thrive. The plant has a summer resting period when it should be kept dry and so it is best grown in a cold greenhouse or bulb frame. Placing a cloche over outdoor-grown plants in the summer, especially after flowering, will help to ripen the bulbs. Most members of this genus are intolerant of competition from other growing plants. This species is not fully hardy in Britain and is unlikely to survive in the colder parts of the country. It is only marginally hardy in N.W. England. A new bulb is formed annually, the old one withering away. Grows well with most plants, especially roses, carrots, beet and chamomile, but it inhibits the growth of legumes. This plant is a bad companion for alfalfa, each species negatively affecting the other. Members of this genus are rarely if ever troubled by browsing deer.

Propagating it: Seed - sow spring in a cold frame. Prick out the seedlings into individual pots when they are large enough to handle - if you want to produce clumps more quickly then put three plants in each pot. Grow them on in the greenhouse for at least their first winter and plant them out into their permanent positions in spring once they are growing vigorously and are large enough. Division in spring. The plants divide successfully at any time in the growing season, pot up the divisions in a cold frame or greenhouse until they are growing well and then plant them out into their permanent positions.

Best place to grow: Cultivated Beds;

Habit: Bulb

Hardiness: 7-10

Growth:

Soil: Light (sandy), medium

Shade: No shade

Moisture: Dry, moist

Things to keep in mind

Although no individual reports regarding this species have been seen, there have been cases of poisoning caused by the consumption, in very large quantities and by some mammals, of certain members of this genus. Dogs seem to be particularly susceptible.

Its other names

Local names

Synonyms

A. grandisceptrum.