S4ag Microgreens

Microgreens

Microgreens are the fastest path from seed to harvest on a farm — 7 to 21 days from seeding to cut, with no tillage, no season, and minimal space required. Your goal is a consistent, clean harvest that either feeds your household or earns a premium at market. This skill covers the full path: picking the right varieties for your purpose, designing a system you can actually run, seeding and growing without common failures, and troubleshooting when things go wrong.

How this skill works: Each sub-tool pauses at a Checkpoint to confirm the assumptions it is about to build on before producing output. A recommendation built on a wrong assumption wastes time and money — confirm the checkpoint before acting. Each sub-tool ends with Next steps — the skills worth running once you have acted on this one.

Expert Lineage

The thinkers whose frameworks underpin this skill — and what they specifically discovered that changes how you farm.

Mark Mathew Braunstein — The Microgreen Pioneer Braunstein's early work documented microgreens as a distinct horticultural category separate from sprouts — a distinction that matters practically because microgreen production requires a growing medium, light exposure, and root anchorage that sprout production does not. His specific contribution: the observation that cotyledon-stage harvesting captures peak nutritional density in most brassicas before secondary metabolism shifts resources into leaf structure. For the grower, this sets the harvest timing window — wait for the first true leaf on most species, not after.

Johnny's Selected Seeds Research Programme — Agronomic Benchmarks Johnny's conducted systematic trials on seeding density, germination rates, and yield per tray across the major microgreen species. Their most actionable finding: most growers under-seed by 30–40%, producing a thin, leggy crop prone to damping-off and uneven germination. Dense seeding produces mutual support between stems, keeps humidity at root level, and drives the thick, uniform mat that makes professional-quality harvests. Their published seeding rates by species are the best single reference for system calibration.

Cornell Controlled Environment Agriculture (CEA) Group — Media and Nutritional Research Cornell's CEA programme conducted comparative trials on growing media and nutritional outcomes. Their finding that most directly changes practice: soil-grown microgreens — including a mix with biologically active compost — consistently produce higher mineral density than sterile soilless media, particularly for zinc, iron, and calcium. The biological activity in a compost-based medium appears to mediate mineral bioavailability at the root surface even in the very short growing cycle. For growers who care about nutritional density, this makes a strong case for a compost fraction in the medium.

Elaine Ingham — Soil Food Web (Applied to Short-Cycle Growing) Ingham's framework applies here in a limited but real way: even in a 10-day crop, a biologically active growing medium outperforms sterile media for plant health indicators and mineral uptake. Her principle that plants access nutrients through biological mediation — not direct soil chemistry — holds even at microgreen timescales. Practically: a medium with 20–30% finished compost introduces sufficient microbial activity to improve mineral availability, and spent microgreen trays with root mats intact are a higher-value compost input than plain organic matter because they carry an established microbial community.

Jean-Martin Fortier — Small-Scale Market Production Economics Fortier's market garden framework — high value per square metre, direct marketing, crop mix optimisation — applies directly to microgreens at market scale. His specific insight: the crops worth growing for market are those with the highest revenue per unit of time, not per unit of space. Microgreens, priced at $25–50/kg retail, satisfy this test better than almost any field crop. His tracking methodology — revenue per tray, sellout rate, waste percentage — is the management system that separates a profitable microgreen operation from a hobby.

Charles Dowding — No-Dig Principles (Applied to Tray Systems) Dowding's no-dig research on minimal soil disturbance has an analogue in microgreen production: the growers who produce the most consistent harvests are those who treat the tray as a managed biological environment rather than a disposable substrate. His principle that biology, once established, does work the grower does not have to do applies: a medium with active biology handles pH buffering, moisture management, and early pest suppression in ways sterile media cannot. Spent tray material composted and reintroduced into the growing medium creates a biological feedback loop analogous to Dowding's compost-mulch cycle.

Which tool fits

Routing Decision

• Just starting out, don't know which species to grow → variety-selection
• Have species chosen, building or buying a system → system-design
• System in place, want a step-by-step process guide → seeding-and-growing
• Something has gone wrong — mould, yellow, sparse, pest → troubleshooting
• Unclear → variety-selection first; species choice determines everything downstream

Variety Selection

Identifies which microgreen species suit your purpose, skill level, and market.

Not all microgreens are equal to grow. Some species germinate at near 100% with minimal management; others require pre-soaking, blackout periods, or humidity control to produce reliably. Start with the easiest and most marketable before adding difficult species. The framework below lets you match species to your situation.

Tier 1 — Easy, fast, high market demand: These species suit beginners and form the backbone of any market operation.

Tier 2 — Medium difficulty, strong market value:

Tier 3 — Specialist or difficult: These reward experienced growers but fail unpredictably for beginners.

For household use: Radish, broccoli, peas, and sunflower give the best return for the effort. Grow one at a time until the process is reliable.

For market: Build a base of three to five Tier 1 species for volume and reliability. Add one or two Tier 2 species for visual interest and premium pricing. Add Tier 3 only when you have a confirmed buyer.

Checkpoint — confirm before finalising:

• Household use or market production? The economics of a market operation require species with sufficient margin and volume.
• If market: do you have confirmed buyers, or are you developing the market? Confirmed buyers allow specialisation; market development requires a broader safe range.
• Climate and growing space temperature? Basil and corn require 21–24°C minimum; most other species perform at 16–21°C.

A species recommendation built without knowing the end use produces the wrong variety mix and the wrong seeding density plan.

Output:

MICROGREEN VARIETY SELECTION
Purpose: [household / market — channel confirmed or to develop]
Environment: [indoor / outdoor / polytunnel / temperature range]

RECOMMENDED STARTING SPECIES
1. [Species] — [days to harvest] — [reason for inclusion]
2. [Species] — [days to harvest] — [reason for inclusion]
3. [Species] — [days to harvest] — [reason for inclusion]

SECONDARY SPECIES (add once confident with above)
- [Species] — [days to harvest] — [specific market or nutritional reason]

SPECIES TO AVOID FOR NOW
- [Species] — [reason — difficulty, market, temperature mismatch]

ESTIMATED WEEKLY PRODUCTION (if market)
Trays per week to target: [number]
Approx revenue per tray at $[price]/kg: $[amount]

Next steps:

• Run system-design (within this skill) — your species list determines tray sizing, light needs, and media depth.
• /s4ag-market — if selling at farmers market, variety mix and presentation decisions overlap with stall design and product mix.
• Run seeding-and-growing (within this skill) once system is in place.

System Design

Designs the physical setup — trays, media, lighting, and space — to match your species list and scale.

A microgreen system has four physical components: trays, growing medium, light source, and environmental control. Each decision constrains the others. Work through them in sequence.

1. Tray selection

The 10x20 inch (25x51 cm) standard nursery flat is the industry default — widely available, stackable, compatible with most accessories. Use two trays per grow: a solid bottom tray (no holes) to hold water and a perforated insert tray for the growing medium.

2. Growing medium

Growing medium is the most consequential system decision for nutritional quality.

Soil health note: A 20–30% compost fraction introduces biological activity that improves mineral uptake even in the 10–14 day growing window. Spent trays with the root mat intact are a higher-value compost input — add them directly to an active compost pile rather than discarding.

3. Light requirements

LED specification for market production:

• Hang 30–45cm above tray surface during growing phase (after blackout)
• Target 12–16 hours of light per day — use a timer
• Target PPFD of 150–250 µmol/m²/s for most microgreens — do not need the intensity required for fruiting crops
• Full-spectrum (blue + red + white) performs better than red/blue only for flavour and colour development

4. Space and airflow

• Minimum ceiling height for shelving with lights: 45cm between shelf levels (tray + 30–45cm hang)
• Air circulation is critical: stagnant humid air is the primary driver of mould. A small fan producing gentle air movement across trays reduces mould incidence dramatically.
• Temperature: 18–22°C is ideal for most species. Below 15°C, germination slows significantly. Above 26°C, risk of damping-off increases.

5. System scale calculator

Checkpoint — confirm before finalising:

• Indoor or outdoor / polytunnel? Outdoor and polytunnel systems need a different light and temperature management approach.
• Is this for year-round production or seasonal? Year-round requires artificial light and heat management.
• Budget range for setup? LED racking for market scale is a real capital investment — confirm the budget before specifying.

Building a system without knowing the light situation and budget produces a design that doesn't match the reality.

Output:

MICROGREEN SYSTEM DESIGN
Scale: [household / CSA / market — trays per week target]
Environment: [indoor / polytunnel / mixed]

TRAY SETUP
Tray size: [10x20 / custom dimensions]
Tray configuration: [solid base + perforated insert / alternative]
Medium depth: [cm]

GROWING MEDIUM
Formula: [soilless only / soilless + compost ratio / mat]
Compost source: [on-farm finished / purchased — confirm quality]
Notes: [any species-specific medium variation]

LIGHTING
Source: [LED / T5 / natural / supplement]
Hang height: [cm above tray]
Hours per day: [number — use timer]
Estimated power cost: [per week if electric]

ENVIRONMENT
Temperature target: [°C range]
Airflow: [fan size / placement]
Humidity management: [note — lower is safer for mould]

SPACE REQUIRED
Shelving: [dimensions / rack configuration]
Total footprint: [m²]

ESTIMATED SETUP COST: [$/ range]
WEEKLY OPERATING COST: [$/ range — electricity + medium + seed]

Next steps:

• Run seeding-and-growing (within this skill) to put the system into operation.
• /s4ag-controlled-environment — if you are moving toward a fully controlled growing environment at meaningful scale, the CEA skill covers environmental management in more depth.
• /s4ag-finance — before scaling to market production, run the enterprise economics.

Seeding and Growing

Step-by-step from seed preparation through to harvest.

This sub-tool assumes you have chosen your species and designed your system. If not, run variety-selection and system-design first.

The production cycle has six stages:

Stage 1: Seed preparation (Day 0)

Do not pre-soak: radish, broccoli, mustard, cabbage, basil (mucilaginous), amaranth. Soaking these increases mould risk without germination benefit.

After soaking, drain and rinse. Do not let soaked seeds sit wet — seed them immediately.

Stage 2: Seeding (Day 0)

1. Fill the perforated insert tray with growing medium to 2–3cm depth (or 4–5cm for peas and sunflower). Press lightly to eliminate air pockets. Do not compact — roots need pore space.
2. Moisten the medium until damp throughout but not waterlogged. Squeeze a handful — it should hold shape and release no water when squeezed hard.
3. Distribute seed evenly across the surface. Aim for a single dense layer — seeds touching but not piling. Reference seeding rates in variety-selection above.
4. Press seeds lightly into contact with the medium. A second tray pressed flat on top for 10 seconds works well.
5. Mist the seed surface with clean water.
6. Cover with a blackout dome or inverted tray weighted down.

Stage 3: Germination under blackout (Days 1–4)

• Stack trays or apply weight equivalent to 1–2 kg. This presses the seed into contact with the medium and encourages straight, strong stem development.
• Check moisture once daily. Lift the dome and mist if the surface looks dry. Do not waterlog — mist the surface only.
• Remove the dome when the tallest seedlings are pressing against it — typically day 2–4 depending on species and temperature.
• In warm conditions (22°C+), check on Day 2 — fast germinators push domes up quickly and will etiolate if left dark too long.

Stage 4: Light phase (Days 4–12+, species-dependent)

• Move trays under light or to a sunny window immediately after dome removal.
• Seedlings will green up within 6–12 hours of light exposure. If they remain pale yellow after 24 hours, light intensity is insufficient.
• Watering: bottom-water where possible. Pour 2–3cm of water into the solid base tray; the perforated insert will absorb from below. This keeps the canopy dry — the leading mould-prevention technique.
• If top-watering is necessary, water at the base of the plants, not over the canopy.
• Water once daily is typical, but monitor — medium should be moist, not saturated or dry.

Stage 5: Harvest (Days 7–21, species-dependent)

Harvest method:

• Use clean, sharp scissors or a harvesting knife
• Cut 1–2cm above the medium surface — you want stem, not root mat
• Cut just before use for maximum freshness, or harvest and refrigerate immediately
• Pack loosely — do not compress — in breathable packaging or containers
• Refrigerated shelf life: 5–10 days depending on species. Peas and sunflowers last longest; basil is shortest.

Stage 6: Post-harvest tray management

• Spent trays can go directly to a compost pile. The root mat is a high-value compost input — dense with microbial biomass.
• If reusing trays: remove root mat, rinse with water, air dry. Do not reuse medium — start fresh each grow.
• Track each tray: date seeded, species, harvest date, fresh weight. This data drives the variety-selection and system-design decisions over time.

Checkpoint — confirm before finalising:

• Have you confirmed the temperature of the growing space? Germination failure is most commonly a temperature problem.
• Is the water source chlorinated? Chlorinated tap water can suppress the compost biology in your medium. Let it sit for 30 minutes before use, or use filtered water.
• Do you have a timer for lights? Manually managing light hours is the fastest route to inconsistency.

Germination failure, leggy growth, and mould are the three most common failures — all are process problems, not species problems. If something goes wrong, go to troubleshooting.

Output:

MICROGREENS PRODUCTION LOG
Tray ID: [number or code]
Species: [species name]
Seeded: [date]
Pre-soaked: [yes / no — hours]
Medium: [formula]
Seeding rate: [g used]

GERMINATION BLACKOUT
Dome applied: [date]
Dome removed: [date] — [height at removal: cm]
Moisture check notes: [any issues during blackout]

LIGHT PHASE
Light start: [date]
Water method: [bottom-water / top-water]
Any problems noted: [yes / no — describe]

HARVEST
Harvest date: [date]
Days to harvest: [number]
Fresh weight: [g]
Tray yield: [g/tray]
Quality notes: [colour, density, flavour]

TRAY DISPOSAL
Medium: [composted / discarded]
Tray: [cleaned for reuse / retired]

Next steps:

• Run troubleshooting (within this skill) if the harvest does not meet expectations.
• /s4ag-composting — to make full use of the spent tray root mats as compost inputs.
• /s4ag-market — once you have consistent production, take the next step toward selling.

Troubleshooting

Diagnoses and resolves the most common microgreen production failures.

Most microgreen problems fall into four categories: mould, germination failure, poor growth (leggy or pale), and pest problems. Work through the diagnosis below, then apply the targeted fix.

Problem 1: Mould

Mould is the most common and serious failure mode. White fuzzy growth on the medium surface or stem bases is almost always one of three things: excessive moisture, insufficient airflow, or contaminated medium or seed.

Prevention protocol (implement all four):

1. Bottom-water only — keeps canopy dry
2. Fan providing gentle continuous air movement across trays
3. Germination room temperature below 23°C
4. Seed at the correct density — too sparse increases mould risk because canopy doesn't close and moisture sits on the medium surface

Problem 2: Germination failure or uneven germination

Seed viability test: Scatter 10 seeds on a damp paper towel, fold, seal in a bag, leave at room temperature for 5 days. Count germination percentage. Below 80% — buy fresh seed.

Problem 3: Leggy, pale, or weak growth

Leggy growth (long, thin stems) and pale or yellow colour are both light problems. Dense, short, richly coloured growth is the target.

Light troubleshooting: If you suspect light is the problem, measure the distance from the light to the tray surface. For LEDs, the optimal range is 30–45cm. For window growing, the plant needs 4+ hours of direct sun or 6+ hours of bright indirect light — fewer hours than this produces leggy growth regardless of species.

Problem 4: Pest problems

Microgreens grown indoors have limited pest exposure, but three pests appear commonly.

The most effective pest prevention in microgreens is sanitation: clean trays between uses, do not allow standing water, and do not let finished or rotting plant material sit near growing trays.

Problem 5: Off flavour or texture

Checkpoint — confirm before finalising:

• Is this a one-off failure on a single tray, or a recurring pattern across multiple trays? One-off failures are usually process errors; recurring patterns point to a system design problem.
• What is the temperature in the growing space at night? Many failures that seem like day problems are actually night temperature drops.
• When did you last replace your growing medium, and what is its source? Old or contaminated medium causes a surprising proportion of recurring mould and germination problems.

Treating a symptom without confirming the underlying cause produces the same failure on the next tray.

Output:

MICROGREENS TROUBLESHOOTING REPORT
Tray ID: [number]
Species: [species]
Problem observed: [description]

DIAGNOSIS
Most likely cause: [cause]
Contributing factors: [list]
Confidence: [high / medium — low means gather more information]

IMMEDIATE ACTION
[What to do with the current tray — harvest early / discard / continue monitoring]

SYSTEM FIX
[What to change for the next tray to prevent recurrence]

NEXT TRAY TRIAL
Adjust: [specific change — e.g. reduce seeding depth to 3cm, add fan, switch to bottom-watering]
Monitor: [what to watch and when]

Next steps:

• Run seeding-and-growing (within this skill) with the corrected process on the next tray.
• /s4ag-composting — if mould is systemic, review the compost fraction in your medium for quality and maturity.
• /s4ag-market — if production is now consistent, address the market side.