Komatsuna Green Boy – Known in Japan as “Small Pine Greens” for its Long History

Komatsuna (小松菜), meaning “small pine greens,” has been a staple in Japanese kitchens for centuries. Its name comes from the Komatsugawa area near Tokyo, where legend says Shogun Tokugawa Yoshimune first enjoyed the vegetable in the early 1700s and gave it its lasting name. The Green Boy variety is a modern strain, compact and tender, bred for quick growth. With smooth, glossy green leaves and pale stems, it offers a flavour that sits between spinach and pak choi, with a gentle mustard note.

Growing Komatsuna var. Green Boy

Komatsuna is well suited to the UK climate. It grows best in fertile, moist but well-drained soil and can cope with either full sun or partial shade. Naturally tolerant of cold, it will keep producing longer into autumn, and under cover it can continue right through winter. Green Boy’s compact size also makes it perfect for containers and raised beds.

Sowing and Planting

Sowing Period: March to September outdoors; under cover in cooler months.
Soil Preparation: Rake to a fine tilth and enrich with compost or well-rotted manure.
Sowing Depth: 1 cm.
Spacing: 15 cm for baby leaves, 25 cm for mature plants; 30 cm between rows.
Germination: 7–14 days.

Care and Maintenance

Watering: Keep soil evenly moist; dry conditions can toughen the leaves and cause bolting.
Feeding: Beds usually only need compost at sowing; in pots, add a light liquid feed every 2–3 weeks.
Protection/Pests: Flea beetles and pigeons are the main issues—mesh or fleece offers reliable protection.

Picking

Timing: Baby leaves are ready in 3–4 weeks; mature plants in 6–8 weeks.
Method: Snip outer leaves regularly for a steady supply, or cut whole plants just above the crown to allow regrowth.
Storage: Keep leaves in a breathable bag in the fridge; use within a few days for the best flavour and crunch.

Culinary and Garden Uses

• A Tokyo favourite, eaten daily in soups, pickles (tsukemono), and stir-fries.
• Traditionally eaten at New Year in Japan for good luck and long life.
• Mild enough for salads but sturdy enough to use like spinach or pak choi.
• Compact plants are perfect for pots, raised beds and small gardens.

Allergy Information

Komatsuna belongs to the mustard family (Brassicaceae). Both the seeds and leaves may not be suitable for those with mustard allergies.