How to Grow Sea Kale USA

By the SoilCommander Editorial Team, under the guidance of Nitin Sharma, Co-Founder · · How we check our facts

On this page
  1. Sea Kale (Crambe maritima)
  2. Soil & Growing Conditions
  3. Growth Stages
  4. Quick Facts
  5. At a Glance
  6. Harvest & Storage
  7. Diseases
  8. Pests
  9. Plan your Sea Kale planting
  10. Growing Sea Kale in another region
  11. Sources
  12. Frequently Asked Questions

Sea kale (Crambe maritima) — perennial.

Unlike an annual crop, the work here is front-loaded into establishment: get the planting and the site right and the same plants crop for several seasons.

The short answer

Site
soil pH 6.5–7.5
Biggest risk
Club root

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

Sea Kale (Crambe maritima)

Purple sea kale shoots emerging from the ground in spring — “Crambe maritima kz09” by Krzysztof Ziarnek, Kenraiz is licensed under CC BY-SA 4.0.

Also known as: sea cabbage · 7 sources cited · Verified

Soil & Growing Conditions

A sea kale plant growing on coastal sand
A sea kale plant growing on coastal sand. Photo: “Sea kale - Crambe maritima” by MrPanyGoff, CC BY-SA 3.0.

Soil pH range

6.5 7.5

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

Growth Stages

A sea kale plant in flower with white blooms
A sea kale plant in flower with white blooms. Photo by Krzysztof Ziarnek, Kenraiz, CC BY-SA 4.0.
Stage BBCH Notes
Propagation 0 Sow seed in pots in spring or autumn, divide in early spring, or take 15cm root cuttings (thongs) in late autumn -- straight cut nearest the plant, slanting cut at the far end -- and store upright in damp sand until March (RHS, Gardeners World).
Planting and establishment 1 Plant thongs in early spring under about 2cm of compost, or with the strongest bud 2.5cm below the surface, in a sheltered, sunny, sharply drained site; plants take 2-5 years to reach full size (RHS, Gardeners World).
Crown building and flowering 5 Leave the crown unforced through its first year to build strength; mature plants make mounds of blue-green wavy-edged leaves topped with small white flowers in early summer (RHS).
Forcing and harvest 4 From the second year onwards, cover crowns over winter with a rhubarb forcer or upturned bucket; snap or cut the pale blanched shoots once finger length or more and eat raw or steamed (Gardeners World).

Quick Facts

A mound of lobed wavy-edged blue-green sea kale leaves
A mound of lobed wavy-edged blue-green sea kale leaves. Photo by Krzysztof Ziarnek, Kenraiz, CC BY-SA 4.0.
Factor Value
Soil pH 6.5 - 7.5
Optimal growing temp 57-75°F (14-24°C)
Minimum survivable temp 23°F (-5°C)
Drainage Well-drained
Lifecycle perennial
Edible parts blanched shoots, leaves, flowering shoots

At a Glance

A sea kale plant in flower with white blooms
A sea kale plant in flower with white blooms. Photo by Krzysztof Ziarnek, Kenraiz, CC BY-SA 4.0.
Crambe maritima Sea Kale Club root Slugs Cabbage caterpillars DISEASES PESTS

Harvest & Storage

Purple sea kale shoots emerging from the ground in spring
Purple sea kale shoots emerging from the ground in spring. Photo by Krzysztof Ziarnek, Kenraiz, CC BY-SA 4.0.

When to pick: RHS: shoots grown for eating are "usually blanched for several weeks before harvesting"; young wavy-edged blue-green leaves are also edible and used as a cooked vegetable, and young flowering shoots bearing small white flowers are "cooked like sprouting broccoli".

Storage

Best used fresh soon after blanching and harvest

Diseases

A mound of lobed wavy-edged blue-green sea kale leaves
A mound of lobed wavy-edged blue-green sea kale leaves. Photo by Krzysztof Ziarnek, Kenraiz, CC BY-SA 4.0.

Plasmodiophora brassicae

Pests

Sea kale in full white flower on a rocky shoreline
Sea kale in full white flower on a rocky shoreline. Photo: “Crambe maritima (3676714910)” by Randi Hausken from Bærum, Norway, CC BY-SA 2.0.
Slugs

Gastropoda (slugs, various spp.)

Cabbage caterpillars

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

Plan your Sea Kale planting

When to sow and plant Sea Kale depends on your own frost dates. Check the USA vegetable planting calendar. To work out where it fits in your beds, sketch your plot in the free Garden Layout Planner.

Growing Sea Kale in another region

Sowing dates, frost timing and local advice differ by country. Use the guide for where you garden.

Sources

The full list of 7 sources behind this guide (BBC Gardeners World Magazine, FAO EcoCrop, GBIF and others) is in the references of our UK guide to sea kale; they describe the plant itself, which is the same wherever it grows.

Frequently Asked Questions

What soil pH does sea kale need?

A pH of about 6.5–7.5. 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 sea kale?

Our data links 1 disease and 2 pests to this crop. See the sections above for each one and how to manage it.

Plan next season before the problems start

Almost everything on this page resolves to your own frost dates rather than the calendar — the last spring frost moves by roughly two months between zone 3 and zone 10. The USA Garden Planner works from your zone so the timing is already decided before the season starts.

Get the USA Garden Planner →

Instant PDF download · Written for US growing conditions

SoilCommander Editorial Team — under the guidance of Nitin Sharma, Co-Founder

Every growing guide is checked against RHS, USDA Cooperative Extension, and other named horticultural authorities before publishing. How we check our facts.

How this guide is put together

The growing data on this page — sowing windows, pests, diseases, soil and site requirements — comes from named horticultural sources, listed in References below, checked against USDA hardiness-zone and frost-date data, with Cooperative Extension sources cited directly where one exists for a crop. An automated pipeline assembles that verified data into the page you're reading: it selects which facts to lead with and builds the surrounding prose and layout. It does not invent a date, a source or a number — where a verified value for a field isn't available, the page leaves it out rather than guessing. A person reviews and publishes each page; nothing goes live unverified.

Vegetable Growing Guides USA

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Last verified 2026-09-02

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