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The tray becomes cuttable when the seed leaves have opened flat and gone fully green, which is normally two to three days after uncovering and eight to ten days from sowing in a room at 65 to 70F (18 to 21C). At that point the stems are three to four inches (8 to 10 cm) tall, white, and snap rather than bend.
You have roughly three days of good eating from there. On the first day the shoot is mild and sweet with a clean radish finish. By the third it is noticeably hot, and the seed leaves have started to darken and toughen at the edges. By day five the first true leaf is showing, the stem is fibrous near the base, and the heat is aggressive rather than pleasant.
There is no benefit at all in waiting for size. The stem stops lengthening once the leaves are working, so the extra days buy you fiber and pungency and nothing else. If the tray is ready and you are not, cut it and refrigerate it rather than leaving it standing.
| Stage | Days from sowing | Stem height | Flavor | Verdict |
|---|---|---|---|---|
| Seed leaves still folded | 6 to 7 | 2 to 3 in (5 to 8 cm) | Very mild, watery | Too early, poor yield |
| Leaves open, pale green | 7 to 8 | 3 in (8 cm) | Sweet, faint heat | Good for salads and children |
| Leaves flat and deep green | 8 to 10 | 3 to 4 in (8 to 10 cm) | Clean, distinctly peppery | The target, best all-round |
| Leaves darkening at edges | 10 to 12 | 4 in (10 cm) | Sharp and hot | Use as a seasoning, not a salad |
| First true leaf visible | 12 or more | 4 in (10 cm) plus | Harsh, stems fibrous | Past it, compost the tray |
Heat builds faster in a warm room. At 76F (24C) the pleasant window can be down to about a day and a half, so a tray you would have left until the weekend in winter needs cutting on the day in a warm spell.
Cut once, at the base, with scissors
Use sharp scissors and cut the whole mat in one pass, holding a handful of shoots lightly upright with your free hand and shearing just above the surface of the medium. Do not pull, and do not cut into the medium, because everything below your cut line comes with the crop and grit in a mat of shoots cannot be rinsed out afterwards.
Cutting half an inch (1 cm) above the medium loses you almost nothing in length and keeps the harvest completely clean. It also leaves the root mat intact, which makes it far easier to lift out and compost in one piece.
Cut into a dry bowl. Shoots harvested wet and then piled up start breaking down within hours, and the difference between a bowl that keeps five days and one that goes slimy in two is almost entirely whether the mat was dry when it was cut.
- Stop watering the evening before Let the surface dry slightly overnight so the stems are not carrying free water when they are cut. Do not let the tray wilt; a slightly dry surface is the target, not a dry mat.
- Gather a handful upright Hold the shoots gently together so they stand vertical. This gives you a level cut line and stops the scissors dragging half the mat sideways.
- Shear just above the medium Half an inch (1 cm) clear of the surface. Work across the tray in strips rather than trying to reach into the middle, and keep the blades parallel to the surface.
- Check the base of the harvest Look for stuck seed coats and any soft brown stems and pick them out now. One rotting stem in a sealed box will take a good bowl of shoots with it in two days.
They do not regrow, so plan trays in succession
The growing point of a radish shoot is at the top, between the seed leaves, so cutting at the base removes it. Nothing regrows. Occasionally a tray pushes out a few weak side shoots from a stump over the following week, and they are thin, bitter and not worth the shelf space.
The tray is therefore one crop, and continuous supply means starting a new tray rather than waiting on an old one. Sowing a fresh tray every four or five days gives an unbroken run, since the cycle is eight to ten days and two trays overlap comfortably.
Tip the spent root mat and medium out whole into the compost and wash the tray properly before it is reused. Reusing the medium for a second sowing of shoots gives you a much higher rate of damping off, because the old root mat is already carrying whatever was in the first tray.
Washing and storing the cut shoots
Only wash the shoots if you are eating them immediately. Wet shoots do not store. If you must rinse a batch for the fridge, spin them properly in a salad spinner and let them sit on a dry towel for twenty minutes before they go into a box.
Store in a rigid container in the fridge with a dry paper towel in the bottom and the lid on but not sealed airtight. Kept dry at 38 to 40F (3 to 4C) they hold five to seven days, staying crisp for the first three or four and softening after that. Loose in a bag they last two days.
They do not freeze and they do not revive. A limp bowl of shoots stays limp, so the answer to a soft batch is to use it cooked, stirred into something hot at the last second, rather than trying to crisp it in cold water like a lettuce.
| Storage method | Keeps | Notes |
|---|---|---|
| Rigid box, dry, lid resting on | 5 to 7 days | The best option, stays crisp 3 to 4 days |
| Rigid box, washed and not dried | 2 days | Slime starts at the cut ends first |
| Loose in a plastic bag | 2 days | Crushes and sweats against itself |
| Left standing in the tray | 1 to 2 days of quality | Keeps growing, heat and fiber climb |
Record the cutting day and the weight
Weigh what you cut and write it next to the seed weight and the sowing date. The ratio is the number that tells you whether a tray went well: about ten to fourteen times the seed weight is a healthy return, and anything under eight means you lost part of the mat somewhere, usually at the base and usually to damp.
Note the flavor too, in one word. Mild, right, or hot. After half a dozen trays the log will tell you exactly how many days at your normal room temperature give the version you actually like, which is not necessarily the day everyone else calls ready.