How to Grow Linseed Microgreens in Australia

Brown linseed, also sold as flaxseed (Linum usitatissimum, family Linaceae), is grown here as tray shoots that are cut green and eaten raw. The shoots taste mild and nutty, and are usually ready 10 to 14 days from the soak. Wet linseed turns to jelly, so it grows on a tray, never in a sprouting jar.

Three mistakes that matter

1. Sprouting it in a jar. The seed coat turns to a thick gel in water, so a jar cannot drain and the seed sits in its own slime. Soak it briefly, spread it on a tray, and never rinse it.
2. Spreading the gel thickly. Seed sunk in deep jelly stays wet and airless, so few seeds root and mould has time to start. Spread the gel thin.
3. Letting the gel dry out. Linseed needs to stay moist from the soak to the cut, and a tray left dry on a warm day can stop growing. Mist it 2 to 4 times a day while it is covered.

When to sprout

Linseed shoots grow indoors in any month, and a room near 21°C suits them. A cold kitchen slows them. A warm, humid one speeds them up but helps mould take hold in the gel.

In a muggy Brisbane February or a Darwin wet season, choose the airiest room you have rather than the warmest.

Food safety

Linseed shoots start as raw sprouts, in warm, damp conditions that suit bacteria. Bacteria inside a contaminated seed cannot be washed away.

• Grow untreated linseed sold for sprouting, never seed sold for sowing a crop, which can carry fungicide, as which seeds to sprout explains.
• Wash your hands first. Wash and rinse the tray, cover, bowl, spray bottle and scissors, then sanitise them before the first batch and between batches. Use a dishwasher that can sanitise, usually on its longest, hottest setting. Otherwise, soak them in very hot water (77°C for 30 seconds). Or soak them for 30 seconds in plain unscented household bleach at 25 mL to 10 L of cold water. Make it up fresh each day, use it as its label directs, and let everything air-dry.
• Soak, mist and water only with water fit to drink, and use a fresh lining for every tray.
• Keep shoots and trays away from raw meat, poultry and seafood, and store the shoots above them in a fridge at 5°C or colder. Cooked sprouts for anyone at higher risk are eaten straight away. Leftovers are cooled, kept in the fridge, used within a day of cooking and reheated until steaming hot.
• Mould, slimy gel or a sour smell end a tray: bin the shoots, compost the lining and wash the tray. Sprouts can carry harmful bacteria while looking, smelling and tasting normal, so none of those is a test of safety. See sprout problems and safety.

What you need

Use a shallow tray or dish with no drainage holes, lined with a coir mat or a few layers of paper towel. Add a tray or plate as a cover, a bowl, a spray bottle, clean scissors and brown linseed sold for sprouting.

These amounts leave a little space around each seed. The gel can also go straight into a clean, unlined dish, as the product page describes, though seed sitting deep in gel roots poorly.

Soaking and Sowing

Start in the morning, because the gel wants a misting every couple of hours on its first day.

1. Tip the seed for your tray into a clean bowl.
2. Pour in about one and a half times its volume of cool drinking water, enough to cover it.
3. Leave it 2 to 4 hours, until the seed has taken up the water and set into one jelly mass. Do not drain or rinse it.
4. Wet the lining through, so it is saturated but not dripping, and tip off any water pooling in the tray.
5. Spoon the gel onto the lining and spread it thin and even, with a little space around each seed.
6. Mist the surface, cover the tray and set it somewhere still and dim, out of direct sun.

Water must not pool in the tray, because standing water is where mould starts.

Day by day

Damp without puddles decides the tray: gel and lining moist, tray floor dry. Days count from the start of the soak.

Once uncovered, the shoots need at least five hours of good light a day, out of hot direct sun. A fan on low or a window open nearby keeps damp air moving over the tray.

Cutting and Storing

The shoots are ready once the seed leaves have opened green, usually at 2.5 to 7.5 cm tall. Cut them earlier for a milder flavour. Use clean scissors just above the lining, leaving the hulls and any unsprouted seed behind.

Keep water off the shoots for their last 8 to 12 hours, so they go into the fridge dry. Seal them in a clean container and refrigerate them as Food safety describes. They lose quality fast, so eat them within a few days. Rinse them under cool running water just before use, then add them raw to salads and sandwiches, or stir them through a hot dish.

Raw linseed naturally contains cyanogenic glycosides, which release hydrogen cyanide when the seed is chewed, crushed or ground. Food Standards Australia New Zealand lists linseed among the foods that contain them. Germany's Federal Institute for Risk Assessment says baking or cooking lowers the risk. It expects no harm in adults from up to 15 to 20 g of ground raw linseed a day. It advises that young children are not given raw ground linseed. That amount is for ground seed and does not apply to the shoots. Young flax shoots make these compounds too, and no source gives an amount for them, so use them as a garnish rather than a bowlful.

Common problems

White fuzz on the roots. Root hairs coat the roots only, evenly, and collapse when misted. Mould can be white too, or grey, green or black, and grows in patchy, cobwebby tufts over seed, gel and lining. It stays after a misting and smells musty, and the tray goes out as Food safety describes.

Sour smell or slimy gel. Water has pooled in or under the gel in still air. Throw the tray out, and tip off pooled water sooner next time.

Few seeds sprouting. Old seed, a cold room or seed sunk in deep gel can each slow or stop it. Move the next tray somewhere near 21°C and spread fresh seed as Three mistakes that matter describes.

Pale, thin, flopping shoots. They had too little light after the cover came off. Move the tray somewhere brighter, as Day by day describes.

Tips

1. Start a small tray each week for a steady supply.
2. An unglazed terracotta dish soaks up excess water, which suits a seed that holds so much of its own.
3. Dry seed can keep for up to about three years sealed in a cool, dark, dry cupboard.
4. The microgreens article covers trays, light and watering for other shoots grown the same way.

Due to quarantine restrictions and our shipping policy, we cannot send brown linseed to Western Australia or Tasmania.