Allium hyalinum (Glassy onion)

Botanical name

Allium hyalinum

Other names

Glassy onion

Genus

Allium Allium

Species

A. hyalinum - A. hyalinum is a compact, clump-forming, bulbous perennial with linear, mid to light green leaves and, in spring, umbels of glossy, white to pale pink flowers turning transparent with age.

Native to

California

Foliage

Deciduous

Fragrance

Scented leaves

Habit

Erect, Clump-forming

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Colour

Flower

Pale-pink, White in Spring

Foliage

Green in Spring; Green in Winter

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How to care

Watch out for

Specific pests

Leaf-mining sawflies

Specific diseases

Onion rot , Powdery mildew

General care

Pruning

Deadhead to prevent self-seeding. Do not remove leaves until they have completely died down.

Propagation

Sow seed in a cold frame in autumn. Self-seeds readily in ideal growing conditions. Separate bulbs in autumn.

Propagation methods

Offsets, Seed

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Monthly care advice

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Where to grow

Allium hyalinum (Glassy onion) will reach a height of 0.3m and a spread of 0.9m after 2-5 years.

Suggested uses

Beds and borders, Bees (attract & feed bees), Cottage/Informal, Gravel, Rock

Cultivation

Grow in fertile, well-drained or moist but well-drained soil in full sun or partial shade. Where native, grows in heavy clay and rocky outcrops in sun or shade. Plant in autumn 5-10cm deep. Best with plenty of water from winter into spring. Keep dry in summer when dormant.

Soil type

Chalky, Clay, Loamy, Sandy (will tolerate most soil types)

Soil drainage

Moist but well-drained, Well-drained

Soil pH

Acid, Alkaline, Neutral

Light

Partial Shade, Full Sun

Aspect

South, West

Exposure

Exposed, Sheltered

UK hardiness Note: We are working to update our ratings. Thanks for your patience.

Hardy (H4)

USDA zones

Zone 8, Zone 7, Zone 6, Zone 5

Defra's Risk register #1

Plant name

Allium hyalinum (Glassy onion)

Common pest name

allium leaf miner

Scientific pest name

Phytomyza gymnostoma

Type

Insect

Current status in UK

Present (Limited)

Likelihood to spread in UK (1 is very low - 5 is very high)

3

Impact (1 is very low - 5 is very high)

3

General biosecurity comments

Pest of Allium already present in UK and spreading; previous consultation supported awareness raising only; industry should prepare for the event of findings in commercial crops.

Defra's Risk register #2

Plant name

Allium hyalinum (Glassy onion)

Common pest name

Asain cotton leafworm; Cluster caterpillar; Fall armyworm; Rice cutworm; Taro caterpiller; Tobacco budworm; Tobacco caterpillar; Tobacco cutworm; Tobacco leaf caterpillar

Scientific pest name

Spodoptera litura

Type

Insect

Current status in UK

Absent

Likelihood to spread to UK (1 is very low - 5 is very high)

3

Impact (1 is very low - 5 is very high)

3

General biosecurity comments

Regulated pest; frequently intercepted with occasional outbreaks which have been successfully eradicated in the UK.

Defra's Risk register #3

Plant name

Allium hyalinum (Glassy onion)

Common pest name

Nematode; common spiral; Spiral nematode; Steiners spiral nematode

Scientific pest name

Helicotylenchus dihystera

Type

Nematode

Current status in UK

Absent

Likelihood to spread to UK (1 is very low - 5 is very high)

2

Impact (1 is very low - 5 is very high)

3

General biosecurity comments

Nematode pest unlikely to be very damaging in its own right; but used as a an indicator species to assess compliance of soil requirements of imported plants to be kept under review in light of EFSA evaluation of soil requirements.

About this section

Our plants are under greater threat than ever before. There is increasing movement of plants and other material traded from an increasing variety of sources. This increases the chances of exotic pests arriving with imported goods and travellers, as well as by natural means. Shoot is working with Defra to help members to do their part in preventing the introduction and spread of invasive risks.

Traveling or importing plants? Please read "Don't risk it" advice here

Suspected outbreak? Click here for contact details to report to the relevant authority.

Date updated: 7^th March 2019 For more information visit: https://planthealthportal.defra.gov.uk/