White Mustard

White mustard (Sinapis alba) is a fast-growing annual in the cabbage family, native to the Mediterranean region but now cultivated worldwide. It is grown for its mildly spicy seeds used in condiments, as a green manure crop, and as a sprouting green. The plant thrives in cool conditions and tolerates light frost, making it well suited to Nordic kitchen gardens. It establishes quickly and suppresses weeds effectively when grown as a cover crop.

Growing

Sow seeds directly into the ground once soil temperature reaches 5 °C. Press seeds 1 cm deep in rows spaced 20–25 cm apart, thinning seedlings to 10 cm within rows. Seeds germinate in 4–7 days. For sprouts, scatter seeds densely in a sprouting tray or jar with no soil, keeping moist; sprout height of 3–4 cm is reached in 4–5 days. No indoor starting is needed — direct sowing suits this species perfectly.

Care

White mustard requires minimal care. Water consistently to keep soil evenly moist, especially during germination and early growth. No feeding is necessary when grown in average garden soil; on very poor soils a balanced fertiliser at sowing helps establishment. When grown as green manure, cut or till the crop into the soil before it sets seed. For seed production, support is rarely needed as stems are sturdy.

Harvest

For sprouts, harvest when shoots reach 3–4 cm, typically 4–5 days after soaking, rinsing at least twice daily to prevent mucilage build-up. For mustard greens, cut young leaves once plants reach 10–15 cm tall. For seed, allow pods to turn yellow-brown and begin to dry; harvest the whole plant and dry further in a warm, ventilated space before threshing. As green manure, cut the crop down just as flowering begins for maximum organic matter.

In the kitchen

Young sprouted seeds add a mild, peppery bite to salads, sandwiches, and grain bowls. Mature seeds are ground or cracked to make mustard condiment, used whole in pickling brines and spice rubs, or steeped in dressings and marinades. Young leaves can be used raw in salads or lightly wilted as a peppery side green. The flavour is milder and less pungent than brown or black mustard.

Storing

Store dried, cleaned seeds in an airtight glass jar in a cool, dark place; they keep well for up to two years. Fresh sprouts should be refrigerated in a ventilated container and consumed within 3–4 days. Mustard greens can be blanched and frozen for up to six months.