How to grow microgreens for market. Twelve steps, soak to sealed clamshell. Fix it from only $3 a month.

Step 1. Work backwards from pack day

Pick the day the greens leave the building. Then count back. Days to cut are not a matter of opinion, they are the numbers set out below, and every other date in the run hangs off them.

Write the sow date, the uncover date and the planned cut date on masking tape and stick it on the end of the tray before it goes on the rack. Not on a whiteboard across the room. On the tray.

Do not skip: if the variety needs a soak, the soak begins the evening before the sow date. Put that on the calendar as its own entry, because a forgotten soak pushes the whole run back by a day and the entire schedule shifts with it.

Step 2. Soak the seed, then rinse it until the water runs clear

Sunflower and pea take a soak. Weigh the seed into a bucket, cover it with about three times its own volume of cool water, lay the lid on loose and leave it 8 to 12 hours. Past twelve hours the water turns sour and the coats go slick.

Tip the bucket into the colander. Rinse under cool running water, turning the seed with your hand, until what comes out the bottom is clear rather than cloudy. Then let it drain a full ten minutes before it touches a tray. Seed that goes on still dripping lands in clumps, and clumps rot.

Radish, broccoli and salad mix go on dry. Do not soak them. The seed is small enough to take up what it needs from the surface within the hour, and a soaked brassica turns into a gel you cannot spread.

Note down: soak start time, soak end time, and the drained weight if you weigh wet. Soaked seed close to doubles, so weigh dry and be strict about which number you write down.

Step 3. Fill the tray, level it, then sow by weight

Fill to about a finger width below the rim. Drag a straight edge across the rim to strike the surface flat, tamp once with the base of an empty tray, and pre-moisten until a squeezed handful keeps its shape and gives up one drip. Not a stream. One drip.

Set the empty cup on the scale, press tare, then pour to the weight from the schedule above. Do not scoop by feel. A tray that goes on light comes off light, and you find out on pack day when you are three punnets short.

Scatter in two passes, half the seed north to south and the rest east to west, then rock the tray gently side to side to settle every seed into contact with the surface. Bare patches are weight you paid for and will never see.

Step 4. Cover, weight it, set the uncover alarm

Invert a second tray over the top so the seed germinates in darkness. Sunflower gets weight on top as well, five to ten pounds of full trays or a couple of clean bricks, until day 2. Pea, radish, broccoli and salad mix take the cover with no weight at all.

Set a phone alarm for the uncover morning, matched to the date on the masking tape. Every additional day under the cover is stem you did not want and canopy you will struggle to pack tidily.

Check on uncover morning: lift a corner before you commit. You want an even mat of white or pale stems with the seed coats mostly shed. Patchy and ragged means the sow was thin, which is a step 3 problem, not a cover problem.

Step 5. Water from below once the cover is off

Stop watering the canopy the day the cover comes off. Pour into the outer tray instead, roughly a quart per 10 by 20, and let it wick up for ten to fifteen minutes. Then tip off whatever has not been taken up.

A tray left with water pooled under it sours at the root mat, and you will smell it at the pack bench three days later. Once a day is normal. Twice in a hot dry room. Press a thumb into the corner of the medium: cool and springy means wait, dry and firm means water.

Step 6. Judge the cut day with three checks, never the calendar alone

The date on the tape tells you which morning to look. These three checks tell you whether to cut.

1. Cotyledons fully open and flat, with the first true leaf just visible at the crown rather than fully out.
2. Canopy level when you crouch and look across the tray at eye height. A tray with a dip in the middle is not ready, it is ragged.
3. The mat lifts as one sheet when you tug a corner, so the roots have knitted and the tray will cut cleanly instead of shredding.

Cut in the morning while the leaves are turgid and the room is still cool. And hold the water for the twelve hours before the cut. A dry canopy cuts cleaner, dries faster afterwards, and packs without fogging the lid.

Step 7. Set the pack bench up before the first tray comes off the rack

Twenty minutes of setup here removes almost every reason a pack day runs late. Do it while the room is still cool.

• Wipe the bench, the scale platform, the blade and the spinner basket with sanitizer, then let them flash off dry rather than towelling them.
• Fill a clean basin with cold water if you wash, and set a drainboard or a rack beside it so nothing wet touches the bench.
• Line two crates with clean towels for cut greens, and put an open bin at the end of the bench for hulls, trimmings and spent mats.
• Stack the clamshells open, lid back, in the order of the pack list so you are never hunting for a size mid-run.
• Write the cut date onto the labels now, in one sitting, while your hands are clean and dry.
• Switch the cooler on and let it pull down to temperature. A cooler started at the same moment as the first cut is warm for an hour, which is exactly the hour that matters.
• Tie your hair back, apron on, hands washed to the wrist. Boring, and the whole reason a buyer keeps taking your product.

Step 8. Cut the tray

Gather a section of the canopy in your free hand, hold it upright without squeezing, and draw the blade straight through at a steady height above the medium. Draw it, never saw it.

Roughly half an inch of clear stem below the leaves is the cut line for most varieties. High enough to leave the seed hulls, the root mat and the medium behind. Low enough that you are not throwing weight away.

Work in sections from one end of the tray to the other, and lay each handful into a towel-lined crate rather than dropping it in. Every drop bruises, and a bruise browns overnight.

Sunflower only: one additional pass. Run spread fingers through the cut greens and lift out the shells that came away with the leaves, or fan them off over the waste bin. Do this before anything gets wet, because a damp shell glues itself to a leaf and stays there.

Step 9. Decide about washing, then never vary it

Unwashed greens keep longer and go into the clamshell dry, which is most of the shelf-life battle won before you begin. If you cut half an inch above the medium and your grow room is clean, unwashed is the simpler discipline.

If you do wash, wash the same way every single time. One dunk in cold water, thirty seconds, hands moving gently underneath. Then lift the greens up out of the basin rather than pouring the water off through them, so the grit stays at the bottom instead of settling back into the leaves. Never leave a batch soaking while you wander off to do something else.

Step 10. Dry until a handful will not mark a paper towel

Spinner work goes in small batches, basket half full at most, three or four short pulses rather than one long spin. Over-spinning presses the canopy into a mat and creases the cotyledons.

For a bigger run, spread the greens loose on the fan-dry rack with a fan on low, fifteen to twenty minutes, turning once with spread fingers halfway through.

The test: press a small handful against a paper towel. If it darkens the towel, keep drying. One drop of loose water inside a sealed clamshell is fog on the lid within the hour and slime by day three.

Step 11. Portion into clamshells on a tared scale

Set an empty clamshell on the scale and press tare so the container weight comes off the reading. Repeat that whenever you swap clamshell size, and re-zero the scale if anything spills.

Fill to your stated weight plus a small overage, two to four percent, because greens give up a little moisture in the cooler and a short punnet is the one thing nobody forgives.

Fill loose. Lift with spread fingers and let the greens fall in with air between them. A pressed punnet weighs correctly and looks half empty. A loosely filled one looks full, keeps its shape all the way to the door, and lifts out without a crease in it.

Snap the lid shut until the catch clicks. Stack no more than four high while you work.

Step 12. Label, then get it cold and keep it cold

Every clamshell shows four things: farm name, variety, cut date, and a batch code that ties the punnet back to one tray. A batch code that works is the sow date plus the tray position, for example 0812-R3, so any query about any punnet traces to one tray in one week. Write the same code on the pack list beside the drop it went to.

Clamshells go into the cooler within thirty minutes of the cut. Target 34 to 38 degrees F. Do not push warm punnets tight together, leave a finger of air between the stacks for the first hour so the field heat has somewhere to go.

For the drive, ice packs at the bottom and the top of an insulated tote, clamshells in the middle, and never a punnet in direct contact with the ice. A frozen leaf goes translucent and there is no recovering it. Load the crates at the very end and drive with them out of the sun.