Allium porrum 'Below Zero'

RHS Plant Profile
leek 'Below Zero'
Herbaceous Perennial Herbs - Culinary

A vigorous, cold tolerant leek with white stems and dark leaves to a height of 45cm, stands well over a long period without bolting. Tolerates extreme cold well and is resistant to rust. Leeks are herbaceous perennials usually grown as annual vegetables, with upright stems which can be blanched white, and green or blue-green leaves about 30-50cm long; plants may flower by bolting in their first year, or the following year if left overwinter, with stems up to 1.5m high topped by rounded flowerheads 5-9cm across of hundreds of star-like pale pink to white flowers which are visited by bees, in summer.

Position

Full sun, Partial shade

Soil Types

Chalk, Clay, Loam, Sand

Max Height

0.1-0.5 metres

Max Spread

0.1-0.5 metres

Size

Time to Maturity
1–2 years
Max Spread
0.1-0.5 metres
Max Height
0.1-0.5 metres

Growing Conditions

Chalk Clay Loam Sand
Moisture
Moist but well–drained
pH
Acid or Alkaline or Neutral

Position

Full sun Partial shade
Aspect
East–facing or South–facing or West–facing
Exposure
Exposed or Sheltered
Hardiness
H4

Colour & Scent

Season Stem Flower Foliage Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family
Amaryllidaceae
Native to GB/Ireland
No
Foliage
Evergreen
Habit
Clump forming
Genus
Allium are bulbous herbaceous perennials with a strong onion or garlic scent, linear, strap-shaped or cylindrical basal leaves and star-shaped or bell-shaped flowers in an umbel on a leafless stem
Name Status
Accepted

How to Grow

Cultivation

Sow seed, under cover in late winter or early spring or outside in late spring, about 1cm deep in moist but well-drained soil that is rich in organic matter, preferably in full sun though they will tolerate partial shade; thin seedlings to 15cm apart, or, to get the classic white stems, lift and re-plant seedlings from spring to early summer in holes 15cm deep at 15cm spacings, and harvest from late summer or early autumn to winter; for more advice, see leeks cultivation

Propagation

Propagate by seed. See sowing vegetable seeds

Pruning

No pruning required

Pests

May be susceptible to slugs and snails, leek moth, onion fly and onion thrips

Diseases

May be susceptible to leek rust, onion white rot, downy mildews, foot and root rots, fungal leaf spots, and smuts; Below Zero is said to be resistant to rust