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How to Grow Siberian Kales Canada | Complete Growing Guide

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Siberian Kale (Brassica napus var. pabularia)

Siberian Kale ('Ragged Jack') growing in a heritage seed bed — “CBG Fruit Veg Island - Anniversary Heirloom Beds, Brassica napus 'Ragged Jack' Siberian Kale 150627 (20329896065)” by cultivar413 from Fallbrook, California is licensed under CC BY 2.0. Source: Wikimedia Commons

3 sources cited · Verified

The short answer

Site
6+ hours of sun, soil pH 6–7.5
Biggest risk
Brassica downy mildew

Siberian kales (Brassica napus var. pabularia) — annual or biennial grown as an annual.

Core growing advice on this page is checked against named horticultural sources — see References.

At a Glance

A young Siberian Kale plant showing purple leaf veining — “Brassica napus 'Ragged Jack' Siberian Kale, young plant showing purple leaf veining (Barstow garden collection)” by Stephen Barstow is licensed under CC BY 4.0. Source: GBIF
Brassica napus 'Ragged Jack' Siberian Kale, young plant showing purple leaf veining (Barstow garden collection)” by Stephen Barstow is licensed under CC BY 4.0. Source: GBIF.
Brassica napus var. pab… Siberian Kale Brassica downy mildew Club root Aphids Cabbage caterpillars Flea beetles DISEASES PESTS

Quick Facts

Siberian Kale ('Ragged Jack') growing in a heritage seed bed — “CBG Fruit Veg Island - Anniversary Heirloom Beds, Brassica napus 'Ragged Jack' Siberian Kale 150627 (20329896065)” by cultivar413 from Fallbrook, California is licensed under CC BY 2.0. Source: Wikimedia Commons
CBG Fruit Veg Island - Anniversary Heirloom Beds, Brassica napus 'Ragged Jack' Siberian Kale 150627 (20329896065)” by cultivar413 from Fallbrook, California is licensed under CC BY 2.0. Source: Wikimedia Commons.
Factor Value
Soil pH 6 - 7.5
Sunlight 6-6 hours direct sun
Soil texture fertile soil (RHS)
Drainage well-drained
Lifecycle annual or biennial grown as an annual
Edible parts leaves

Soil & Growing Conditions

A young Siberian Kale plant showing purple leaf veining — “Brassica napus 'Ragged Jack' Siberian Kale, young plant showing purple leaf veining (Barstow garden collection)” by Stephen Barstow is licensed under CC BY 4.0. Source: GBIF
Brassica napus 'Ragged Jack' Siberian Kale, young plant showing purple leaf veining (Barstow garden collection)” by Stephen Barstow is licensed under CC BY 4.0. Source: GBIF.

Water: keep well-watered (RHS); benefits from compost or nitrogen-rich fertiliser worked in before planting (Properly Rooted)

Soil pH range

6 7.5

Span reflects genuine variation between the cited authorities, not a single agreed figure.

Growth Stages

Close-up of Siberian Kale's distinctive purple stem base — “Brassica napus 'Ragged Jack' Siberian Kale, close-up of purple stem base (Barstow garden collection)” by Stephen Barstow is licensed under CC BY 4.0. Source: GBIF
Brassica napus 'Ragged Jack' Siberian Kale, close-up of purple stem base (Barstow garden collection)” by Stephen Barstow is licensed under CC BY 4.0. Source: GBIF.
Stage BBCH Notes
Sowing 0 Sow indoors mid-spring, prick out to modules or individual pots (RHS); or direct sow after last frost up to six weeks before first frost (Properly Rooted).
Transplanting 1 Transplant out early summer, May-July, in rows 60cm apart (RHS).
Low, clustered leaf growth 3 Grows low and clustered, closer to the ground, rather than from a central stalk like most kale; keep well-watered and net against birds and insects (Properly Rooted, RHS).
Cut-and-come-again harvest 8 Harvest leaves at any size with a sharp knife; exceptionally cold-hardy, down to 10F, mature plants to -20F (Properly Rooted).

Harvest & Storage

A mature Siberian Kale plant showing its purple stem — “Brassica napus 'Ragged Jack' Siberian Kale, mature plant showing its distinctive purple stem (Barstow garden collection)” by Stephen Barstow is licensed under CC BY 4.0. Source: GBIF
Brassica napus 'Ragged Jack' Siberian Kale, mature plant showing its distinctive purple stem (Barstow garden collection)” by Stephen Barstow is licensed under CC BY 4.0. Source: GBIF.

When to pick: Harvest leaves at any size, from baby to full-grown, cutting with a sharp knife (Properly Rooted). Exceptionally cold-hardy: hardy down to 10F, mature plants may withstand as low as -20F (Properly Rooted).

Diseases

Siberian Kale ('Ragged Jack') growing in a heritage seed bed — “CBG Fruit Veg Island - Anniversary Heirloom Beds, Brassica napus 'Ragged Jack' Siberian Kale 150627 (20329896065)” by cultivar413 from Fallbrook, California is licensed under CC BY 2.0. Source: Wikimedia Commons
CBG Fruit Veg Island - Anniversary Heirloom Beds, Brassica napus 'Ragged Jack' Siberian Kale 150627 (20329896065)” by cultivar413 from Fallbrook, California is licensed under CC BY 2.0. Source: Wikimedia Commons.
Brassica downy mildew
moderate

Hyaloperonospora brassicae (syn. Peronospora parasitica)

RHS names this directly for the Pabularia Group.

moderate

Plasmodiophora brassicae

RHS names this directly for the Pabularia Group: club root.

Pests

Siberian Kale with purple stems growing through snow — “Brassica napus 'Ragged Jack' Siberian Kale, plant with purple stems in snow (Barstow garden collection)” by Stephen Barstow is licensed under CC BY 4.0. Source: GBIF
Brassica napus 'Ragged Jack' Siberian Kale, plant with purple stems in snow (Barstow garden collection)” by Stephen Barstow is licensed under CC BY 4.0. Source: GBIF.
low

Aphididae (various spp.)

Properly Rooted names this directly: aphids.

Cabbage caterpillars
moderate

Pieris brassicae; Pieris rapae; Pieris napi; Mamestra brassicae; Plutella xylostella

RHS names this directly for the Pabularia Group: cabbage caterpillars.

Flea beetles
moderate

Chrysomelidae: Alticini (various spp.)

RHS names this directly for the Pabularia Group: flea beetle.

References

  1. A secondary gardening reference rather than a university or horticultural authority, used for growth-habit and hardiness detail specific to Siberian (not Red Russian), not contradicted by the above. Siberian kale produces wide, flat leaves growing closer to the ground, forming a low cluster rather than growing from a central stalk like most other kale. Exceptionally cold-hardy: hardy down to 10F, mature plants may withstand as low as -20F; less heat-tolerant than other kale types. Direct sow after last frost up to six weeks before first frost, or start indoors. Benefits from compost or nitrogen-rich fertiliser worked into the soil before planting. Harvest leaves at any size with a sharp knife. Fewer pest/disease problems than other kale types, but still susceptible to aphids, whiteflies, cabbageworm and cabbage looper.

  2. RHS's general Pabularia Group cultivation page (RHS bundles named cultivars within this group, including Red Russian and other Siberian-type kales, under this Group-level entry and its per-cultivar pages). Grow in fertile, moist but well-drained soil in full sun. Sow indoors mid-spring, prick out to modules/pots, transplant early summer May-July in rows 60cm apart. Keep well-watered, cover with netting against birds/insects. Pests: birds, cabbage caterpillars, cabbage whitefly, cabbage gall weevil, slugs, snails, flea beetle, mealy cabbage aphid, swede midge. Diseases: black rot, club root, brassica downy mildew, foot and root rot, leaf spot, white blister.

  3. A specialist seed-heritage source, used for the specific leaf-colour/shape distinction between Siberian and Red Russian that RHS's Group-level page does not draw out (RHS bundles both under one Pabularia Group page); not contradicted by RHS. Red Russian and Siberian are the two most well-known named varieties of Russo-Siberian (Brassica napus) kale in the US, recognised as distinct cultivars, not interchangeable terms. Red Russian: stems and veins red/purple, leaves deep grey/green, flat with toothed edges, documented in Russia since 1885. Siberian (also "Early Siberian"): blue-green, huge, feather-shaped, slightly curled leaves, no red/purple pigmentation, extremely hardy, vigorous, rapid-growing. Both are recognised as genetically distinct parent stock -- modern crosses such as 'Red Ursa' deliberately combine "the broadleaf frills of Siberian with the colour of Red Russian," which would not make sense if they were the same plant.

3 independent sources are cited for this crop. Where they disagree - soil pH is the clearest case - every figure is preserved rather than averaged into false precision.

Frequently Asked Questions

What soil pH do siberian kales need?

A pH of about 6–7.5. That span reflects genuine variation between the authorities we cite rather than a single agreed figure — the References section lists each source's exact range.

What problems affect siberian kales?

Our data links 2 diseases and 3 pests to this crop. See the sections above for each one and how to manage it.

Plan next season before the problems start

Short-season growing is arithmetic before it is technique: days to maturity against frost-free days decides what will finish at all. The Canada Garden Planner does that subtraction for your region before you sow.

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Instant PDF download · Written for Canadian growing conditions

SoilCommander Editorial Team

Canadian vegetable growing guides · Adapted for Canadian hardiness zones and frost dates

Every SoilCommander guide is written and maintained by our editorial team for real Canadian growing conditions, adapted to Canadian hardiness zones and frost-date data, with provincial agriculture and Canadian university extension guidance cited directly where a crop-specific source exists.

Vegetable Growing Guides Canada

Last verified 2026-08-29

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