Siberian Kale (Brassica napus var. pabularia)
3 sources cited · Verified
The short answer
- Plant
- Early April to early June
- Site
- 6+ hours of sun, soil pH 6–7.5
- Biggest risk
- Brassica downy mildew
In the UK, siberian kales go in the ground early April to early June.
Siberian kales (Brassica napus var. pabularia) — annual or biennial grown as an annual.
Timing is the decision that matters most in the UK: sowing early April, and that same window applies across all 4 regions covered here.
Core growing advice on this page is checked against named horticultural sources — see References.
Regional Planting Calendar
Quick Facts
At a Glance
Soil & Growing Conditions
Growth Stages
Harvest & Storage
Diseases
Pests
Siberian Kale, Known by its Blue-Green, Purple-Veined Leaves
References
-
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.
-
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.
-
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
When should I sow siberian kales in the UK?
In Southern England, from early April. In Scotland, wait until early April. Treat these as a guide rather than a fixed date — the governing rule is to sow only once frost risk has passed and temperatures are reliably warm enough.
When do I sow siberian kales?
Sow early April to early June.
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
Most of the advice on this page comes down to timing and spacing — sowing at the right moment, rotating beds, and giving plants enough airflow. The UK Garden Planner lays your plot out month by month so those decisions are already made before the season starts.
Get the UK Garden Planner →Instant PDF download · Written for UK growing conditions
Last verified 2026-08-29
Where To Go From Here
Take this crop from reading into a written plan for your own beds.
Plan the next step
Use the printable SoilCommander planner for your region to turn this guide into sowing dates, bed layouts and weekly garden tasks.