How to Sow Rice Seed at Home and Raise Seedlings in a Tray

The seed has to still be wearing its husk

Rice seed is a whole grain still inside its hard, straw-colored husk, and it looks nothing like the white grain you cook. It is longer, pointed at one end, often with a stiff bristle, and it rattles rather than pours. This is the only form of rice that germinates. Milled white rice has had the husk and the bran layer scraped off and the embryo with them, so it will do nothing but ferment in warm water. Brown rice keeps its bran but has still been through the huller, and the huller damages the embryo often enough that a tray of it germinates in patches or not at all.

If you are looking at a bag and cannot tell, rub a few grains hard between your palms. Husked seed keeps its dull, ridged, straw-colored jacket and stays whole. Anything that is already smooth and pale, or that polishes up shiny under friction, is food, not seed. A single tub needs a surprisingly small amount of seed, roughly a tablespoon, so one small packet lasts several seasons if you keep it cool and dry.

Rice seed loses vigor faster than most vegetable seed. Two-year-old seed germinates unevenly and three-year-old seed is usually a waste of a season, so start each year from the freshest seed you can get rather than from the bottom of an old packet.

Soak until the husk splits, not until the sprout shows

Rice will not germinate dry, and it will not germinate cold. Put the seed in a jar of plain water at ordinary room temperature, around 68F (20C), and change the water every day. Cold water is not a problem, it is just slow: at 59F (15C) you will wait a week or more, and at 77F (25C) it can be two or three days. What you are waiting for is the moment a white point breaks the pointed end of the husk. That is the root, and at that stage it is about the length of a grain of sand.

Stop there. It is tempting to leave the jar until the sprouts are half an inch (1 cm) long because it feels like progress, but long white sprouts tangle into a mat, snap when you separate them, and end up sown upside down. The window between a split husk and a tangled mat is about a day at warm temperatures, so check the jar every morning once soaking is under way. Sow the same day the husks open if you possibly can.

Discard any grain that floats after the first hour of soaking. Floaters are empty husks with no embryo inside, and in home-saved seed they can be a fifth of the bag. Skimming them off costs nothing and saves you nursing a tray of blanks for a month.

Raising the seedlings in a shallow tray

Rice is almost never sown straight into its final tub at home. A tray of seedlings is easier to keep warm, easier to keep from drowning, and lets you plant a tub with even, sturdy plants rather than a scatter of whatever came up. Any shallow tray two to three inches (5 to 8 cm) deep will do, filled to within half an inch (1 cm) of the rim with plain garden soil or a heavy potting mix. Do not use a light, peaty seed-starting mix: it floats and the seedlings float with it.

1. Wet the soil to a slurry, then let it settle Add water and stir the soil in the tray until it is the texture of thick porridge, then leave it an hour to settle flat. A level, saturated surface is what stops the seed from washing into one corner later.
2. Scatter the split seed on the surface Sow thickly by vegetable-garden standards, roughly one grain every half inch (1 cm), pointed end down if it lands that way but do not fuss over it. The seed sits on the mud, not in it.
3. Cover with a quarter inch (5 mm) of soil Sieve a thin layer of dry soil over the top and mist it until it darkens. Deeper than this and the shoot exhausts itself before it reaches light. Rice pushes up far less strongly than maize or beans.
4. Keep the tray warm and the soil wet, not flooded Hold the tray at 77 to 86F (25 to 30C) if you can, on a windowsill or a heat mat. Keep a film of water on the surface but never a standing inch, which drowns the seedlings before they have leaves to breathe with.
5. Move to full light the moment green shows Shoots appear in four to ten days depending on warmth. Seedlings kept dim for even two days after emergence stretch into pale threads that flop when you transplant them.

How long to hold them, and what to write down

Seedlings go to the tub when they have three to four true leaves and stand four to six inches (10 to 15 cm) tall, which takes three to five weeks from sowing. Younger than three leaves and they simply vanish under the flood water. Older than five weeks in a shallow tray and they run out of root room, yellow off, and sulk for a fortnight after transplanting instead of getting on with growing.

Thin the tray as they grow, pulling out the weakest so the survivors sit about an inch (2.5 cm) apart. Crowded seedlings make thin, weak stems that lodge later in the season, and it is far easier to thin now than to sort out a tangle of roots on transplanting day.

Write down the date you started the soak, the date green first showed, and the tray temperature you actually managed rather than the one you intended. Rice timing is driven almost entirely by warmth, and after two seasons those three numbers tell you exactly how early you can start next year without the tray stalling on a cold windowsill. Note the proportion of seed that floated too; if it climbs above a quarter, your seed is getting old.