How to Grow Mitsuba in Australia

Mitsuba (Cryptotaenia japonica) is a carrot family perennial (Apiaceae) grown as an annual for its three-part leaves, long tender stalks and microgreens. It is also called Japanese wild parsley or Japanese honewort, but it is neither parsley nor chervil. Unlike most culinary herbs it prefers shade, and treating it like a sun-loving herb is the usual mistake.

Three mistakes that matter

1. Planting it in full sun. In hot sun the leaves turn yellow and bitter, and plants run to flower early. Give it part shade or bright full shade, as Site, soil and setup describes.
2. Burying the seed. Mitsuba seed germinates best with some light, and seed sown deep often never comes up. Barely cover it, keep the surface damp, and allow up to four weeks, as Sowing Seeds explains.
3. Letting the soil dry out. This is a plant of damp woodland and ditches, and it copes very poorly with drying out. Mulch, and water before the surface dries, as Care by growth stage sets out.

When to plant

Mitsuba is a cool-season crop that grows best between 15°C and 25°C. Seed germinates best in soil of about 18°C to 25°C, usually in 1 to 4 weeks. Sow in autumn and spring, and sow again every 4 to 6 weeks for a steady supply.

At the hot edge of a window, sow under cover in a shaded spot and plant out once the weather cools. Summer sowings in hot zones usually flower before they crop.

Site, soil and setup

Choose the spot other herbs refuse: the shaded south side of a fence or shed, or dappled light under a deciduous tree.

Container growing

Mitsuba suits a pot on a shady balcony or verandah, and a pot is easy to move out of summer heat. Use a pot at least 30 cm across holding about 10 to 15 L of quality potting mix, with drainage holes. Sow mitsuba seed across the surface and thin to about three plants. In a pot it usually stays compact.

• Water: whenever the surface feels dry, which can mean daily in warm weather. See watering pots in summer.
• Feed: fish and seaweed blend at half strength, about 12 mL per 9 L, fortnightly once you start cutting.
• Position: morning sun and afternoon shade, out of hot wind.
• Handling mix: potting mix can carry Legionella bacteria, so wet it down, wear gloves and a P2 mask, and wash your hands afterwards.

Sowing Seeds

Start mitsuba from seed, sown direct where it will grow or in cells for planting out.

Starting under cover

• Fill cells or small pots with moist seed-raising mix and sow three or four seeds in each.
• Cover with no more than 3 mm of fine mix, just enough to hide the seed, then firm it.
• Keep the mix damp and warm, at the soil temperature When to plant gives. Seedlings appear unevenly over 1 to 4 weeks.
• Thin each cell to the strongest seedling once they can be handled.

Sowing direct

Rake the bed fine and water it. Sow thinly in rows 15 to 20 cm apart and sift a bare 3 mm of fine compost over the seed. Keep the surface damp until seedlings show. When they reach about 7 cm, thin to 15 to 20 cm apart and eat the thinnings.

Planting out

Plant out seedlings 5 to 10 cm tall, with four or five true leaves. Harden them off first (get them used to outdoor conditions a little more each day) for about a week, as hardening off seedlings describes. Set them 15 to 20 cm apart and water them in.

Care by growth stage

Steady moisture and shade decide this crop, and cutting keeps it leafy.

If growth stalls in poor soil, scratch all-purpose controlled release granular (NPK around 14-5-10) into the surface once, at half the label rate.

Bolt Management

Bolting (running to flower) sends up stems up to 1 m tall, and the leaves turn bitter once a plant flowers. A rosette that flowers dies once its seed ripens, although side crowns from the same root often carry on.

• Cut stalks often, taking the largest first, so the plant keeps making leaves.
• Snip each flower stem off at the base as soon as it appears.
• From early summer, shade beds from afternoon sun with shade cloth or the taller companions Companion planting names.
• Keep sowing at the interval When to plant gives, so young plants are ready as older ones bolt.
• Leave one or two plants to flower in a spare corner if you want self-sown seedlings.

Companion planting

Mitsuba fills shade that most crops cannot use, so pair it with plants that make shade or share its needs.

Grows well with

• Chervil, a herb that shares its liking for moist, part-shaded ground.
• Taller sun-loving plants such as tomatoes and sweet corn, planted on its western side so their foliage blocks the afternoon sun.
• Woodland or alpine strawberries, which share its moist, lightly shaded ground.

Keep apart

• Mint, which spreads by creeping runners through the same damp, shady soil and crowds mitsuba out.

Harvesting Leaves and Stalks

First cuts are usually ready 7 to 9 weeks from sowing, once stalks stand 15 to 20 cm tall.

• Cut whole stalks near the base with scissors, leaving the crown to regrow.
• Take the outer stalks first and leave the young centre stalks.
• Once a plant keeps sending up flower stems and its leaves turn bitter, pull it and cut from a younger sowing.
• For seed, cut dry flower stalks and strip the seed into a paper bag.

Leaves wilt quickly. Rinse cut stalks, wrap them in a damp paper towel and keep them in a bag in the fridge.

Leaves, stalks and roots are edible, raw or briefly cooked. Add them to clear soups, rice dishes, salads, sushi and stir fries at the last minute, because long cooking makes them bitter. People allergic to celery, parsley or parsnip should take care, and repeated handling can irritate sensitive skin.

Common problems

Few seedlings come up. Once depth and moisture are right, as Three mistakes that matter explains, old seed is the usual cause, so sow a fresh packet thickly. Wait a full four weeks before resowing.

Seedlings collapse at soil level. Damping off (a seedling rot caused by soil fungi) strikes in wet, crowded mix, so use fresh seed-raising mix, thin early and water less often. Read more

Pale, yellowing leaves. Apart from too much sun, plants cut hard and often can run short of food, so feed as Care by growth stage sets out.

Plants die off in summer. Heat and dry wind finish many plants in warm zones, so sow in autumn and treat summer losses as the end of the crop. Saving seed each year from the plants that survive can, over several years, give a strain that suits your garden.

Pests and diseases

Few pests trouble mitsuba, and before any spray, read the label and use it only as directed.

Slugs and snails (Gastropoda). They chew seedlings to the ground overnight and strip new spring growth, most often after rain. Search with a torch about two hours after dark and remove them. Read more

Aphids (Aphididae). Clusters of small sap-sucking insects gather on soft new growth, which curls and turns sticky. Squash them by hand, hose them off, or spray insecticidal soap on the leaf undersides. Read more

Two-spotted mite (Tetranychus urticae). Tiny mites under the leaves leave yellow stippling, and numbers build fast in hot, dry weather. Hose the undersides early in the morning three days running. Read more

Prevention first

• Thin seedlings to the spacing Sowing Seeds gives, so air moves between them.
• Keep plants in shade and moist soil, where mites do poorly.
• Pull mulch back from seedlings, and check under pots and boards where snails hide.
• Avoid broad-spectrum sprays, which kill the ladybirds and predatory mites that keep pests down.

Tips

1. Store seed somewhere cool, dark and dry, and sow it within a year or two, because mitsuba seed is short-lived.
2. Grow a tray of microgreens: sow thickly on moist mix and cut when seedlings reach about 7 cm. Growing microgreens covers the method.
3. For white, blanched stems in the Japanese style, use a year-old clump whose tops have died back in winter. Clear the dead leaves and heap soil about 20 cm deep over the crown before new shoots appear. Dig the pale shoots as they push through in spring.