Microgreens: the fastest crop

Seed to harvest in 7-14 days, no nutrient solution needed, and high margins if you sell them. Seed density, growing media, and the basics of production.

Microgreens are seedlings harvested at the cotyledon or first true leaf stage, typically 7-14 days after germination. They're the fastest turnaround crop in indoor growing, require minimal equipment, and can be grown in trays on a kitchen counter with nothing more than a growing mat, water, and a window. No pump, no reservoir, no nutrient solution.

If you're new to growing anything indoors, microgreens are the right starting point. The feedback loop is fast enough that you can run 2-3 cycles in the time it takes a lettuce head to mature, learning from each round.

Why no nutrients

Microgreen seeds contain enough stored energy (endosperm) to fuel growth through the harvest stage. The seedling doesn't need external nitrogen, phosphorus, or potassium because it hasn't exhausted its seed reserves yet. You're harvesting before the plant would naturally need to start feeding from the soil or solution.

This means the growing medium is purely structural: something for the roots to grip and something to hold moisture. Coconut coir mats, hemp mats, or a thin layer of fine vermiculite in a shallow tray all work. Some growers use nothing but damp paper towels, though this is prone to mold in humid conditions.

Equipment

A 25 x 50 cm (10 x 20 inch) nursery tray is the standard container. These cost about $2 each and are reusable. You need two trays per batch: one with drainage holes for the growing surface, and one without holes underneath to catch runoff.

Light requirements are modest. A sunny windowsill works for most species, though leggy (stretched) growth indicates insufficient light. A cheap shop light or a single 20W LED panel 15-20 cm above the tray provides more consistent results than a window and eliminates the variability of weather and season.

No heater, no fan, no air pump. Room temperature (18-24 C) is fine for nearly all microgreen species.

The process

Day 0: Soak seeds for 6-12 hours in room temperature water (optional for small seeds like broccoli and radish, helpful for larger seeds like sunflower and pea). Spread seeds densely on the pre-moistened growing mat. Microgreen seed density is much higher than you'd use for full-sized plants: 10-15 seeds per square centimeter for small seeds like broccoli, 5-8 per square centimeter for larger seeds like sunflower.

Days 1-3 (blackout phase): Cover the tray with an inverted tray or a piece of cardboard. Some growers place a weight (another tray with a brick) on top to provide gentle pressure that encourages stocky, strong stems. Keep the mat moist by misting or bottom-watering. No light needed; the seeds germinate in darkness.

Days 3-5: Remove the cover. The seedlings will be pale yellow or white (etiolated). Place the tray under light. Within 24-48 hours, the cotyledons green up as chlorophyll production begins. Continue bottom watering.

Days 7-14: Harvest when the cotyledons are fully expanded and green, or when the first true leaves just start to appear. Cut with clean scissors just above the growing mat surface.

Best species for beginners

Radish: 6-8 days to harvest. Fast, foolproof, peppery flavor. The most commonly recommended first microgreen.

Broccoli: 8-10 days. Mild, slightly sulfurous flavor. High germination rate.

Sunflower: 10-12 days. Nutty, crunchy, substantial. Requires pre-soaking and dehulling (remove the seed shell) or buy pre-hulled microgreen sunflower seed. Larger seed size means fewer seeds per tray but bigger, meatier greens.

Pea shoots: 10-14 days. Sweet, tender, excellent in salads. Use whole dried peas from the grocery store (much cheaper than specialty microgreen seed). Soak overnight before planting.

Wheatgrass: 7-10 days. Primarily juiced rather than eaten whole. Easy to grow, high yield.

Selling microgreens

Microgreens have unusually high margins for a fresh product. A 25 x 50 cm tray of radish or broccoli microgreens produces 150-250g of product. Seeds cost $0.50-2.00 per tray depending on species. Retail price at farmers' markets or to restaurants is $15-30 per 100g tray, or $25-50 per 225g clamshell.

The economics work at small scale because the overhead is minimal (trays, seeds, water, light) and the turnaround is fast (2-4 harvests per month per growing slot). A 1-meter shelf with four levels of LED-lit trays can produce $200-800 per month in revenue, depending on species, market, and consistency.

The limiting factor isn't production. It's sales. Building a customer base (restaurants, farmers' markets, local delivery) takes time, and microgreens are perishable: 5-7 days of shelf life in a sealed container in the refrigerator. You need buyers lined up before you scale production, or the product goes to waste.

Common problems

Mold: White fuzzy growth on the mat or seed husks. Usually caused by poor air circulation, overwatering, or contaminated seed. Increase airflow with a small fan. Don't overwater. Sterilize trays between uses with dilute hydrogen peroxide.

Leggy growth: Tall, thin, pale stems. Not enough light. Move the tray closer to the light source or increase photoperiod.

Uneven germination: Some areas of the tray sprout while others don't. Usually uneven moisture or uneven seed distribution. Mist more carefully during the first few days and spread seeds as uniformly as possible.

Expanding beyond the basics

Once you've run a few successful trays of radish and broccoli, the natural question is what else can you grow. The answer is nearly anything that germinates from seed.

Sunflower and pea shoots are the most substantial microgreens. They're large enough to use as a salad ingredient rather than a garnish, and they have real texture and flavor (nutty and crunchy for sunflower, sweet and tender for pea). Both require pre-soaking: 8-12 hours for sunflower seeds, overnight for whole peas. Sunflower also benefits from dehulling (seed shell removal); you can buy pre-hulled microgreen sunflower seed to skip this step. The shells cling to the cotyledons and create a mess if not removed.

Beet and Swiss chard produce dramatic purple-stemmed microgreens. The seeds are multi-germ clusters (each "seed" is actually a cluster that produces 2-4 seedlings), so spacing is less predictable. They take 10-14 days, slightly longer than radish.

Amaranth produces tiny, brightly colored microgreens (red or magenta stems) in 8-12 days. The flavor is mild and slightly earthy. Primarily used for color in garnish applications.

Nasturtium produces large, round-leaved microgreens with a peppery, mustard-like bite. They take 10-14 days and the seeds are large enough that you can plant them individually for perfectly even spacing.

Food safety for selling

If you plan to sell microgreens, food safety regulations apply. Requirements vary by state and locality, but most jurisdictions that allow cottage food sales or small farm direct sales will cover microgreens. Some key points:

Wash your hands before handling trays and harvesting. Use clean, food-grade trays and containers. Harvest with clean scissors into clean containers. Refrigerate immediately after harvest (microgreens are perishable, with 5-7 days of shelf life at 4 C). Label packages with the harvest date, your farm name, and the variety.

Many farmers' markets and restaurants want to know your growing practices. "No soil, no pesticides, grown on sterile media under LED lights in a clean indoor space" is a strong food safety statement that microgreen growers can make that field growers can't.

Insurance: check whether your homeowner's insurance covers small-scale food sales. Some growers purchase a separate product liability policy ($200-500 per year) for peace of mind.