A long-lived perennial brassica grown for its blanched shoots, which taste like a cross between asparagus and hazelnut.
Crambe maritima · also called sea cabbage, crambe
Windows are counted from the average date of your last spring frost.
Once established, a single crown produces edible shoots for 10 or more years with minimal inputs. The blanched (light-excluded) stems are a genuinely unusual spring vegetable rarely found in markets.
A little history. Native to shingle beaches and sea cliffs of coastal Europe; its thick, waxy leaves reduce water loss in exposed, salt-laden conditions. Documented in cultivation in Britain since at least the late 18th century.
Sow 1 inch deep; keep soil evenly moist but not waterlogged. Seeds have a corky coat — soaking 24 hours before sowing speeds emergence. Seedlings emerge in 10–21 days in warm soil.
Sow seeds 1 inch (25 mm) deep.
Beds strongly preferred — deep, sandy, well-drained soil; containers require at least 18 inches depth and dry out too fast. In containers: 15-gallon tub, minimum 18 inches deep. Space plants 24 inches (60 cm) apart.
Water deeply once a week during the first growing season; established crowns need water only during dry spells. Water when the top 2 inches of soil feel dry. Aim for about 1 inch per week in the establishment year.
Side-dress (scatter fertilizer along the row and water in) once in early spring and once after harvest. What to use: balanced compost or a low-nitrogen organic fertilizer; avoid high nitrogen, which promotes leaf at the expense of shoots.
Remove flower stalks in years 1 and 2 to direct energy into crown development. From year 3 onward, allow flowering after harvest if desired — flowers are edible — but deadhead before seed set to prevent self-seeding.
It's ready when blanched shoots are ready when they reach 6–8 inches tall and are still tightly budded — before any leaf opens fully. Shoots should be pale cream to white from light exclusion. Cut shoots at the base with a sharp knife just below soil level. Harvest over 4–6 weeks maximum per crown; stop once shoots thin noticeably to allow the crown to rebuild for next year.
Use within 2–3 days of harvest; wrap loosely in a damp cloth and refrigerate. Flavor and texture decline quickly after cutting.
Plant additional crowns 1–2 years apart to stagger productive years, since year-1 crowns are not harvested.
Crowns die back naturally after frost. Cut dead foliage to the ground in late fall. Apply a 3–4 inch mulch of straw or dry leaves over the crown to protect against repeated freeze-thaw cycles.
Asparagus
Both are long-lived crops that want a permanent, sharply drained bed, and once asparagus ferns out in summer its tall filigree casts light shade over sea kale crowns, which sulk once temperatures hold above 85F. Set them 3 feet apart so neither is dug into.
Thyme
A strong-smelling low perennial at the bed edge can help hide the cabbage-family scent that cabbage white butterflies and flea beetles follow, and it holds up under low pest pressure. Keep it outside the crown's 24-inch spread.
Chives
Onion-scented foliage often reduces how readily aphids and cabbage white butterflies settle on nearby cabbage-family leaves. Chives are perennial too, so they suit a bed that stays undug for a decade.
Nasturtium
Aphids and cabbage white butterflies often choose nasturtium over sea kale's waxy leaves. Treat it as sacrificial: pull or cut off infested growth rather than leaving a colony to spread onto the crowns.
Strawberry
Old charts keep strawberries away from the cabbage family, though no mechanism has been demonstrated. The practical objection in a sea kale bed is simpler: strawberry runners creep over the crown and make cutting blanched shoots awkward.
Tomato
Tomatoes are replanted, staked and cleared every year, and that annual digging and trampling disturbs a crown that must sit undisturbed for a decade. Their summer bulk also shades and crowds sea kale leaves rebuilding reserves.
A perennial — it holds its spot for years, so it sits outside the annual rotation.
Sea kale sits outside the yearly rotation: one crown holds its bed for 10 years or more as a moderate feeder, fed by compost rather than heavy nitrogen. When you finally retire the bed, dig out the crown and roots, then keep cabbage-family crops out of that ground for at least 3 years because of club root.
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