Cress microgreens: a peppery crop for a tray, a pad or a paper towel

Cress microgreens are a peppery, small-seeded crop that Mississippi State Extension places in its 10 to 15 day group, so expect about two weeks from sowing to a cut, not a few days. They grow on soil, on a grow pad or on paper, which is why it is the classic paper-towel crop, but the paper version is a short crop and the soil version is the one that gives a proper tray.

If you have not grown a tray before, the beginner method covers the whole routine, and cress slots into it.

How long cress takes

Mississippi State Extension arranges its crops by growth rate from sowing. Radish and pea shoots sit in the 7 to 10 day group. Cress sits in the 10 to 15 day group, next to arugula, broccoli and cabbage, and amaranth leads a slower 16 to 25 day group.

That puts cress in the fast half but not at the front. Penn State Extension gives 7 to 21 days as the range for microgreens overall, and cress sits inside it. What moves a tray within the range is warmth and light: Tennessee Extension says microgreens grown indoors prefer 65 to 78 °F, and a cold shelf pushes the date out. Penn State’s harvest guidance is to cut at the base, just above the medium, when the first true leaves are just showing.

Utah State’s per-crop table does not list cress, so it gives no covered time for it. The blackout guide gives the figures for the crops that are in it, and Illinois Extension’s cue works for any seed: cover with a damp paper towel, lift it daily, and take it off once the seedlings push it up.

Seeding rate and yield

Mississippi State Extension gives 2 to 3 teaspoons of cress seed with an expected yield of 3 to 5 ounces. Its listing states no tray size, so treat the teaspoons as a starting point and not a rule for your container. For a fixed tray, Penn State Extension says 10 to 15 g of seed per standard 12 x 20 in. ten-row tray, and 10 to 12 small seeds per square inch as the density for small seed.

Penn State also measured yield. In its greenhouse trial, Persian cress gave 164 g per ten-row tray, level with basil at 165 g and above the 136 g average across crops. Those are greenhouse averages over many cycles with no supplemental light, so a windowsill tray will differ. The yield guide lays out the full table and how to scale it to your tray.

Spread the seed as evenly as you can. Tennessee Extension warns that clumped seed leads to overcrowding, and Penn State’s damping-off page names overseeding as a risk, so a thick, even layer is the goal and a heap is not.

Soil, pad or paper

Cress is small enough to sow on the surface and water in. Tennessee Extension says small seeds such as arugula, kale and broccoli germinate well uncovered as long as the substrate stays moist, and Illinois Extension advises against covering seed with potting soil because it sticks to the leaves. Tennessee suggests a misting nozzle after seeding so the seed does not shift.

Cress seed turns slippery when wet. The soil-free guide advises skipping gel-forming seeds like cress on a pad until you are comfortable, because the gel holds surface moisture and can mold. That makes soil the safer first surface for cress, and it applies to paper as much as to pads. The surfaces also differ in what they feed the crop.

Surface	What it gives you	What to watch
Seed-starting mix	Moisture and, in many mixes, a small starter charge	Bits of mix can cling to leaves at harvest
Grow pad	A clean cut with no mix on the plants	Tennessee says pads supply no nutrition; mold risk from the wet seed coat
Paper towel	Cheapest, fastest to set up	Dries out quickly, no nutrition, short window; mold risk from the wet seed coat

Tennessee Extension says paper and other pads let microgreens grow without peat or particles sticking to the plants, and that on a pad you need to add soluble fertilizer to the water, because these materials do not provide nutrition. Purdue Extension says a microgreens crop needs no fertilizer because the seed holds what it needs to reach the first true leaves. Both are true for different lengths of crop: a cress tray cut early lives on the seed, and one grown on needs feeding. If you do try a pad despite the mold caution above, the soil-free guide covers pad trays in full.

Keep the surface damp, not wet. Penn State and Illinois both prefer bottom watering because it keeps leaves dry, and the bottom-watering guide shows the method. On paper, mist lightly and check daily, since a thin damp sheet dries faster than a tray of mix.

The beginner crop guide groups cress with other gel-forming seeds best left until after an easier first tray, and the soaking guide lists them as a seed not to presoak.

Harvest, flavor and storage

Cut about 1/4 to 1/2 in. above the surface, which is the range Illinois and Purdue Extension both land in. Tennessee Extension notes that cress gives a stronger flavor than milder crops and is often used in smaller quantities, so a modest tray goes a long way on sandwiches and eggs.

White fuzz at the base of a cress tray may be root hairs rather than mold, and the mold versus root hairs guide shows how to tell them apart. Purdue Extension adds that microgreens get more bitter the longer they grow, which is another reason to cut cress on time. For storing the cut crop, Purdue says unwashed in the fridge lasts about a week, and the harvest and storage guide covers washing and shelf life.

Cress grown to full size

Left to grow, garden cress becomes a different crop. The University of Arkansas Extension calls garden cress a hardy, cool-season salad green in the mustard and turnip family, also called peppergrass, to be picked when leaves are 3 to 5 inches long. That is a garden plant, not a microgreen tray. Cress that grows in water as a true aquatic plant is watercress, a separate species covered in hydroponic watercress.

Sources

• Mississippi State University Extension: Microgreen Varieties for the Mississippi Gardener
• University of Tennessee Extension W346-J: Small-Scale Microgreen Production
• Penn State Extension: Growing Microgreens
• Illinois Extension: Growing Microgreens
• Purdue Extension: Grow Microgreens at Home
• University of Arkansas Extension: Garden Cress