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Asian Greens / Brassica Greens · Cool-season greens

Tatsoi (Black Knight)

Black Knight

Fall
Tatsoi (Black Knight) — Young Young
Seedling / just planted

Young tatsoi transplants, a few weeks old, settling into a window-box container (CC BY-SA 2.0).

Generic green tatsoi seedlings; not the 'Black Knight' cultivar.

Photo: david silver from san francisco· CC BY-SA 2.0

Tatsoi (Black Knight) — Growing Growing
Established, filling in

Established, dark glossy tatsoi with upright spoon-shaped leaves, well before the rosette flattens to harvest size (CC BY-SA 4.0).

Dark-leaved tatsoi at species level; not confirmed as 'Black Knight'.

Photo: Idéalités· CC BY-SA 4.0

Tatsoi (Black Knight) — Full grown Full grown
What you’re aiming for

Mature, near-black-green tatsoi rosette with white midribs, flat and dense at harvest size in a field row (Taichung, Taiwan; CC BY-SA 4.0).

Very dark tatsoi strain that closely resembles 'Black Knight', but the cultivar is not named on Commons.

Photo: Ping an Chang· CC BY-SA 4.0

Growing stages

What to look for, and what to do, at each point in its life

Tatsoi 'Black Knight' is a heirloom, extremely cold-hardy tatsoi with unusually dark, mild leaves, sown in September for a winter-long harvest in Decatur's Zone 8a and again in February-March before spring heat pushes it to bolt.

  1. 1

    Sowing

    Early-mid September (fall crop) or mid-February to early March (spring crop)

    You'll see Seeds are tiny, round, and dark reddish-brown, showing nothing above ground for 4-7 days.

    Do Direct sow 1/4 inch deep and keep the soil surface consistently moist until sprouting.

  2. 2

    Seedling

    Days 4-16 after sowing

    You'll see Round seed leaves appear first, then unusually dark, near-black-green, glossy spoon-shaped true leaves that begin forming a tight, flat rosette low to the ground.

    Do Thin to 6-8 inches apart, and watch for flea beetle shot-holes.

  3. 3

    Cut-and-come-again or whole-plant harvest

    Starting 25-30 days after sowing for baby leaves, 40-55 days for a full flat rosette

    You'll see The rosette spreads flat and wide, 8-12 inches across, with glossy, unusually dark green (almost black) spoon-shaped leaves radiating from a central crown.

    Do Harvest outer leaves as needed, or cut the whole rosette at the base.

  4. 4

    Bolting

    Late spring, typically April-May, once daylength lengthens and temperatures push past 70-75°F

    You'll see A central stalk shoots up from the flat rosette, leaves turn narrow, and small yellow four-petaled flowers cluster at the top.

    Do Harvest what remains before leaves turn bitter, then pull the plant or let one flower for pollinators and seed.

  5. 5

    Seed saving

    4-8 weeks after bolting, once seed pods dry from green to brown

    You'll see Flower stalks turn from yellow blooms to slim, brown, brittle pods that rattle with seed when dry.

    Do Cut dry seed stalks into a paper bag, finish drying, then crush and winnow to collect seed.

Techniques — transplant, prune, propagate, divide, seed

Sun

Full sun to part shade; cool weather.

Water

Consistent moisture.

Spacing

Hydro pods / tight in-ground spacing.

Feeding

Steady light feeding.

Care

  • Cool-season crops — spring and fall windows; they bolt in summer heat.
  • Wasabina mustard + tatsoi run permanently indoors in the 2nd hydro unit.
  • Giant Red + Southern Green mustard run outdoors in the wooden structure.

Harvest

Cut-and-come-again; harvest outer leaves.

Watch for

Bolting in heat; aphids/flea beetles.