Direct-Sowing Kale & Asian Greens in Alberta

When to plant

Spring sowing: mid-May once soil hits 5°C. Fall sowing: late July to mid-August for harvest October through November (and beyond, under row cover). The fall crop is genuinely better — cooler temperatures concentrate flavour and remove the bitterness that summer-grown leaves can develop.

Some Asian greens (mizuna, arugula) bolt fast in summer heat. Skip June and July sowings of those — concentrate on spring and fall windows.

How to plant

• Sow seeds 1 cm deep, thinly along furrows 30 cm apart.
• Germination: 5–10 days for most. Mizuna and arugula are fastest (3–5 days).
• Thin kale to 30–45 cm for full plants, or leave at 10 cm for cut-and-come-again baby leaves.
• Asian greens: thin pak choi and tatsoi to 15–20 cm; mizuna and mustard can stay denser at 10 cm.
• Eat the thinnings.

Pest considerations

Kale and Asian greens are brassicas, which means they share the cabbage-moth problem. Smaller leaf crops (mizuna, mustard) usually outpace caterpillar damage and don’t need protection. Kale and pak choi benefit from row cover or weekly Bt spray once white moths appear. Flea beetles can also pepper Asian greens with tiny holes — row cover prevents that too.

Aphids occasionally cluster on kale, especially in late summer. A strong jet of water knocks them off; a spray of insecticidal soap controls heavy infestations.

Variety picks

• Kale — Lacinato (Dinosaur, Tuscan): Long blue-green leaves with bumpy texture. Most popular kale for cooking. Excellent in soups.
• Kale — Red Russian: Frilly purple-veined leaves, mild flavour. Best raw in salads.
• Kale — Winterbor F1: Curly green, very cold-hardy, the kale most likely to overwinter in Alberta.
• Mizuna: Frilly, peppery Asian green. Cut-and-come-again all season. The salad green.
• Pak choi — Joi Choi F1: White-stem, dark green leaves, slow-bolting. Stir-fry standard.
• Mustard — Mizuna or Red Giant: Spicy heat, beautiful leaves. Mature plants are intense; baby leaves are mild.
• Arugula: Sharp, peppery. The faster you harvest the milder it is. Bolts in heat — keep sowing.

Harvesting

For kale, pick outer leaves first and let the centre keep growing — one plant produces from June until well past first frost. For Asian greens, cut whole heads at the base or harvest leaves cut-and-come-again. Mizuna and arugula regrow 2–3 times after cutting; pak choi and tatsoi are usually one harvest.

Frost is your friend. Once hard frosts hit in October, cover beds with row cover or a small cold frame to extend kale and pak choi harvests into late November. Frost-touched kale, in particular, becomes dramatically sweeter — the plant converts starches to sugars as a natural antifreeze.