s4ag-microgreens

name	s4ag-microgreens
description	Microgreens guidance for household growers and small market producers. Use when the user asks about starting microgreens, choosing varieties, setting up trays, fixing mould or germination problems, or selling microgreens at market.
allowed-tools	["Read"]

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

You need to...	Tool
Choose what species to grow for your purpose and market	variety-selection
Design your tray setup, media, and lighting	system-design
Walk through the seeding, germination, and harvest process	seeding-and-growing
Diagnose mould, poor germination, leggy growth, or pests	troubleshooting

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.

Species	Days to harvest	Flavour	Seeding rate (g/10x20 tray)	Notes
Sunflower	10–14	Nutty, mild	90–120g (hulled)	Pre-soak 8h; thick, satisfying texture
Peas	10–14	Sweet, fresh	200–250g	Pre-soak 8–12h; grows tall, popular at market
Radish	7–10	Peppery, sharp	25–35g	Fast and reliable; high visual appeal
Broccoli	10–14	Mild brassica	20–28g	High sulforaphane — nutritional selling point
Mustard	7–10	Spicy	15–20g	Hot varieties (red frills) are visually striking

Tier 2 — Medium difficulty, strong market value:

Species	Days to harvest	Flavour	Seeding rate (g/10x20 tray)	Notes
Amaranth	10–14	Mild, earthy	10–15g	Striking red colour; needs consistent moisture
Beet	12–18	Earthy, sweet	35–50g	Soak 4–6h; slow but dramatic colour
Corn	10–16	Sweet	120–150g	Pre-soak 6h; needs warmth (21–24°C)
Cabbage	10–14	Mild brassica	18–25g	Performs like broccoli; reliable
Basil	14–21	Aromatic	8–12g	Needs warmth; mucilaginous seed — do not pre-soak

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

Species	Challenge	Worth growing for
Cilantro/coriander	Slow, uneven germination; pre-crack seeds	Niche market; distinctive flavour
Fennel	Slow (18–25 days); needs consistent temp	Chefs' market
Wheatgrass	Dense seeding; prone to mould	Juicing market; requires dedicated customer
Celery	Tiny seed; very slow; 20+ days	Flavour concentrated; small market

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.

Tray approach	When to use	Notes
10x20 standard stack	Market scale, repeatable production	Most efficient use of shelf space; easy to source
Smaller custom trays	Household, variety trialling	Less efficient per unit area; easier to handle individually
Shallow (2–3cm depth)	Radish, broccoli, mustard — short-rooted species	Media use is lower; reduce medium cost
Deeper (4–5cm depth)	Peas, sunflower — species that root deeply for stem support	Essential for tall species stability

2. Growing medium

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

Medium	Best for	Limitation
Sterile commercial soilless (peat/coir/perlite)	Fast production, mould control, consistent results	Lowest mineral density in the finished crop
70% soilless + 30% finished compost	General purpose — best balance of control and nutrition	Compost source matters — use finished, odour-free compost only
100% finished compost	Nutritional density focus	Higher mould risk; needs careful moisture management
Jute or hemp mats (soilless)	Wheatgrass, peas, sunflower — species harvested above the root mat	Cannot be reused; fast and clean
Reusable mats (burlap, coconut coir mats)	High-volume operations wanting reduced media cost	Requires cleaning protocol between uses

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

Light source	Appropriate for	Limitations
South-facing window (4+ hours direct sun)	Household scale, summer production	Insufficient in winter or cloudy climates; leggy growth
LED grow lights (full-spectrum, 6500K)	Year-round market production	Capital cost; electricity; heat management
T5 fluorescent	Budget start for market scale	Higher electricity cost than LED; bulbs degrade
Natural greenhouse / polytunnel light	Seasonal production, medium scale	Supplement in low-light months

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

Goal	Trays per week	Shelf length needed	Light footprint
Household (1–2 meals/week)	2–4 trays	1 standard shelf (60cm)	1 small LED panel
CSA supplement / farm shop	10–20 trays	1 rack (4 shelves x 120cm)	2–3 panels
Farmers market 1–2 days/week	30–60 trays	2–3 racks	4–6 panels
Serious market operation	80+ trays	Dedicated space with racking system	Purpose-built lighting grid

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)

Species that need pre-soaking	Soak time	Water temperature
Sunflower (hulled)	8 hours	Room temperature
Peas (whole dry)	8–12 hours	Room temperature
Corn	6–8 hours	Room temperature
Beet	4–6 hours	Room temperature
Fenugreek	6 hours	Room temperature

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 indicator	What to look for
Cotyledon stage (recommended for most species)	Both seed leaves fully open and horizontal; first true leaf just beginning to emerge
First true leaf (some species — peas, sunflower)	One set of true leaves visible; harvest before second set
Taste test	Cut a small sample and taste — peak flavour usually aligns with visual cues

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.

Symptom	Most likely cause	Fix
White fuzz on medium surface only (not on plants)	Fungal decomposers in medium — usually root hairs, not pathogenic	Not a problem — do not spray. It disappears when trays go under light
White fuzz on stem bases with stem collapse	Damping-off (Pythium or Rhizoctonia) — too wet, too warm, no air movement	Cannot save the tray. Identify cause: reduce moisture, add fan, lower temperature
Grey-green fuzzy patches (Botrytis) on canopy	Canopy too wet, humidity too high	Switch to bottom-watering. Increase air movement. Harvest earlier
Widespread surface mould before germination	Contaminated seed or medium	Source cleaner seed. Use fresh medium. Consider 30-second hydrogen peroxide seed rinse (3% solution)

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

Symptom	Most likely cause	Fix
Nothing germinates after 4 days	Temperature too low (<15°C)	Move to warmer space; use seedling heat mat under trays
Patchy germination (50–70% coverage)	Uneven seeding; old seed	Rethink seeding technique; check seed viability
Germination starts then stops	Moisture failed during blackout	Check daily and mist as needed
Species-specific failure (e.g. cilantro)	Seed needs cracking — hard outer shell	Use cracked coriander seed, or gently crack between two hard surfaces
Pre-soaked seed rotting before germination	Over-soaked; anaerobic conditions	Reduce soak time; rinse more thoroughly; seed immediately after soaking

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.

Symptom	Most likely cause	Fix
Long, pale, thin stems	Insufficient light intensity	Move closer to window; increase LED intensity; reduce light distance
Yellowing throughout (after dome removal)	Kept under blackout too long; low light	Ensure dome is removed as soon as seedlings push against it
Stems lean strongly to one side	Uneven light source	Rotate trays 180° daily; reposition light
Short and stocky under dome, then collapses	Medium too wet; damping-off beginning	Reduce watering; improve drainage; use lighter medium
Top growth fine but thin stems at base	Seeded too sparsely — mutual stem support missing	Increase seeding density on next tray

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.

Pest	Identification	Control
Fungus gnats	Small flies at soil surface; larvae in medium eating roots	Yellow sticky traps above trays; diatomaceous earth on medium surface; Bacillus thuringiensis israelensis (Bti) as a drench; bottom-watering reduces surface moisture that draws adults
Shore flies	Similar to fungus gnats but faster-moving; less damaging	Same as fungus gnats; improve drainage
Thrips	Silver-scarred leaves; tiny insects in leaf folds	Difficult in a microgreen system — harvest early if detected; deep clean all trays and surfaces between grows
Aphids	Cluster on new growth	Rinse with water before harvest; deep clean equipment

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

Symptom	Cause	Fix
Bitter or sour flavour	Harvested too late (true leaf development); heat stress	Harvest earlier; reduce temperature
Watery, weak texture	Over-watered; harvested too young	Reduce water; let cotyledons fully develop before cutting
Tough or fibrous stems	Species harvested too late	Species-specific — check variety-selection for correct harvest stage
Poor shelf life (wilts within 1–2 days)	Harvested at peak heat; not pre-cooled	Harvest in the morning; chill immediately; store at 2–4°C

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.