You can grow microgreens indoors with a shallow tray, clean water, suitable seed, a light growing medium and consistent light. The part that usually makes or breaks the first crop is not expensive equipment: it is keeping the tray evenly moist without leaving it saturated, moving seedlings into useful light at the right time, and harvesting cleanly.
This guide takes you through the full indoor process from seed to harvest, with a setup that works for a kitchen shelf, spare table or compact plant rack in South Africa. It also separates the general growing routine from the separate question of grow-light selection, so you can start simply and add equipment only when your room actually needs it.
Quick plan: one indoor microgreens crop from seed to harvest
| Stage | What to do | What to watch |
|---|---|---|
| Choose the crop | Start with one variety per tray so germination and harvest timing stay predictable. | Different species do not all germinate or finish at the same rate. |
| Prepare the tray | Use a clean, shallow food-growing tray with drainage and a matching solid tray underneath. | Avoid containers that cannot drain or cannot be cleaned properly. |
| Sow | Spread seed evenly over moist growing medium and press it into contact with the surface. | Dense piles of seed create uneven moisture and poor airflow. |
| Germinate | Follow the seed supplier’s covering or blackout guidance and keep the medium moist, not waterlogged. | Do not assume every crop needs the same soaking or blackout time. |
| Move to light | Once the crop has emerged, give it consistent light and open airflow. | A fixed lamp distance is not universal because fixtures differ. |
| Water | After emergence, bottom-watering is a useful way to wet the root zone while keeping the canopy drier. | Empty standing water rather than leaving the tray saturated. |
| Harvest | Cut above the growing medium with clean scissors when the cotyledons are developed and the first true leaves are appearing. | Harvest timing depends on species and growing conditions. |
| Handle as food | Use clean tools and drinking-quality water, refrigerate promptly, and wash before eating. | Wet harvested greens can deteriorate faster, so wash close to use when practical. |
Penn State Extension describes microgreens as young edible greens typically harvested once the cotyledons are fully developed and the first true leaves have emerged. Depending on species and conditions, harvest can fall roughly within a 7–21 day window. That range is more useful than promising every crop will be ready in a week.
What are microgreens, and how are they different from sprouts?
Microgreens are young vegetable or herb seedlings grown in a medium and harvested by cutting the shoot above the root zone. You normally eat the stem, cotyledons and emerging true leaves.
They are not the same as sprouts. Sprouts are usually germinated in water and eaten whole, including the seed and root. That difference matters because the production method, harvest stage and food-safety risks are not identical.
Microgreens also vary more than many marketing claims suggest. A USDA Agricultural Research Service study measured vitamins and carotenoids in 25 commercial microgreen varieties and found wide differences between species. The study found generally higher concentrations of several vitamins and carotenoids than in mature counterparts, but that does not support saying that every microgreen contains the same fixed multiple of every nutrient.
For a beginner, the practical advantage is simpler: microgreens use little space, grow quickly, and let you learn sowing, moisture, light and harvest control on a small tray before moving to larger indoor crops.
Which microgreens are easiest to start with?
Begin with one crop at a time. That makes it easier to learn how quickly the seed germinates, how much water the tray uses, and when the crop is ready to cut.
Fast-growing cabbage-family crops such as radish, mustard, broccoli and kale are common beginner choices. Pea and sunflower are also popular, but their larger seeds are handled differently from tiny brassica seed. University extension guides note that some larger or harder seeds can benefit from soaking before sowing, while many small microgreen seeds do not need pre-soaking at all.
The seed packet or supplier instructions should override a generic internet schedule.
A useful first-tray rule is:
- choose a crop sold for edible growing;
- use one variety per tray;
- label the sowing date;
- record whether the seed was soaked or covered;
- note when emergence was even across most of the tray.
That small record becomes more valuable than memorising a universal “three days dark, ten days harvest” recipe that may not fit the next species.
What you need for a simple indoor setup
You do not need a grow tent or a high-power fixture to learn microgreens. Start with the smallest setup that lets you control drainage, light and cleanliness.
Clean shallow trays
A nested tray system is practical: the upper tray has drainage holes and holds the crop, while the lower solid tray catches water and allows bottom-watering.
Food-grade repurposed containers can also work if they are clean, shallow and drain properly. Penn State and University of Maryland Extension both emphasise clean containers and drainage rather than a particular brand of tray.
A lightweight growing medium
A lightweight soilless mix, coco-based medium or a suitable microgreen mat can work. Dense garden soil is less convenient indoors because it can drain poorly and brings unnecessary soil into a food-growing area.
The medium should hold moisture while still allowing drainage. Microgreens are harvested young, so more fertiliser is not automatically better. University of Maryland notes that many home microgreen crops can complete their short cycle without added fertiliser because the seed supplies much of the seedling’s early nutrition.
Seed suitable for edible production
Use seed from a reputable source and avoid seed treated with chemicals that are not intended for food-crop use. Keep the seed dry and labelled, and follow any crop-specific soaking or sanitation directions from the supplier.
Clean water
Use drinking-quality water for irrigation and washing. Water is part of food safety as well as plant care, especially because dense, moist microgreen trays can also create conditions that support microbial growth.
A light source
A bright window may work for a small tray, but consistent artificial light is useful when natural light is weak, short-lived or uneven.
For the lighting-specific question—fixture type, PPFD, timer strategy and distance—use TheOneGrow’s separate microgreens grow-light setup guide. Keeping those details on the lighting page prevents this seed-to-harvest guide from competing with it.
Clean scissors and simple labels
Use clean, sharp scissors or a knife for harvest. Label the crop and sowing date so that you can compare one batch with the next instead of guessing which change improved the result.
How to grow microgreens indoors step by step
Step 1: Clean the tray and prepare the medium
Wash and dry reusable trays before sowing. Fill the draining tray with an even layer of moist growing medium, then level the surface without compacting it into a hard layer.
The medium should feel evenly damp rather than dripping wet. If water pools on top or remains standing in the lower tray before you have even sown the crop, start by correcting drainage.
This is also the time to decide where the tray will live. Keep it away from pets, dirty tools, chemical storage and splash zones around sinks or floor drains.
Step 2: Sow evenly, not simply “as densely as possible”
Microgreens are planted more densely than vegetables grown to maturity, but uniformity matters more than packing every open millimetre.
Spread seed across the full tray instead of leaving heavy clumps in the centre. Gently press the seed into contact with the moist surface. Some crops are left uncovered; others may receive a light covering or a second tray over the top. Follow the seed supplier’s crop-specific instructions.
If the crop requires pre-soaking, drain the seed properly before sowing. Do not automatically soak every variety: university guidance notes that soaking is useful for some larger or hard-coated seeds but is not a universal microgreen step.
Step 3: Manage germination without creating a wet box
Many microgreens are covered during early germination, and some growers use a short blackout period. The goal is to support even emergence, not to create permanently stagnant humidity.
Check the tray every day. Keep the medium moist, but do not repeatedly add water to an already saturated tray. If condensation is heavy, the medium smells sour, or water remains pooled below the tray, reduce excess moisture and improve ventilation.
Once the crop has emerged evenly and is ready for light, remove the cover rather than keeping tender stems enclosed for convenience.
Step 4: Move the crop into useful, even light
Do not use one fixed hanging distance for every grow light. Fixture output, optics, mounting height and tray size all affect the light reaching the leaves.
A sunny indoor position can work for some home trays. Under artificial light, a timer makes the day length repeatable. University of Maryland Extension uses about 16 hours of total daily light exposure as a practical indoor reference, while controlled-environment research shows that microgreen response depends on both light intensity and photoperiod. In other words, “more hours” is not a universal substitute for measuring or observing the actual crop.
For beginners, look for three simple signals:
- the crop greens up after leaving the covered germination stage;
- stems remain reasonably upright rather than leaning strongly toward one side;
- the tray develops evenly across the centre and edges.
If you want to compare fixture output or PPFD rather than judging by appearance, keep that analysis on the dedicated lighting page.
Step 5: Switch to bottom-watering once the stand is established
After emergence, bottom-watering is often easier to control than spraying the foliage repeatedly.
Add a modest amount of water to the solid lower tray and allow the growing medium to take it up through the drainage holes. The goal is an evenly moist root zone. Do not leave the tray permanently sitting in deep water.
Penn State specifically recommends bottom-watering as a way to reduce water contact with the greens while still wetting the medium. It also helps keep dense leaves and stems drier, which is useful in a compact indoor crop.
Water from the crop’s actual moisture condition rather than a rigid “once every day” rule. Room temperature, airflow, tray depth, crop size and growing medium all change how quickly a tray dries.
Step 6: Give the tray air without blasting tender seedlings
Dense microgreen stands hold moisture between stems. Gentle room circulation helps prevent stagnant air, but a fan should not be so strong that young seedlings are flattened or the tray dries unevenly.
Keep the growing space tidy and leave some space around each tray. If you are stacking trays on shelves, make sure the upper shelf does not trap warm, damp air around the canopy.
In a bright South African room, direct sun through glass can also heat a shallow tray quickly. If the crop repeatedly wilts even while the medium is moist, check the actual tray temperature and sun exposure before adding more water.
Step 7: Harvest at the crop stage, not by a fixed calendar date
Microgreens are commonly harvested once the cotyledons are fully developed and the first true leaves have emerged. Different crops reach that stage at different times.
Use clean scissors or a sharp knife and cut above the growing medium. Avoid dragging soil or roots into the harvested greens.
Penn State recommends washing microgreens in fresh drinking water before consumption. Because delicate leaves can lose shelf life after washing, another practical option is to refrigerate them dry and wash immediately before use.
If you are growing for anyone beyond your own household, treat food hygiene as a production requirement rather than an optional gardening detail.
A practical South Africa home setup: window, shelf or T8 light?
| Setup | Best for | Main check |
|---|---|---|
| Bright indoor window | One or two hobby trays where natural light is reliable | Watch for uneven leaning and excess heat at the glass. |
| Open shelf + compact grow light | Repeatable batches in a kitchen, spare room or apartment | Match the light to the actual tray width and keep water away from plugs and controls. |
| Multi-tier rack | Several staggered trays | Plan access, airflow, drainage and safe cable routing before filling every shelf. |
If you want a compact local lighting option, TheOneGrow’s current 2 × 10W T8 LED tube kit is listed for seedlings, leafy greens and microgreens. The product page lists two 10W tubes, a 550 mm tube length and 4/8/12-hour timer settings.
Treat that as product information, not a universal microgreen recipe. The fixture still needs to fit the shelf and provide useful distribution across the tray.
Common problems: what to check before changing everything
| Symptom | Check first | Better next step |
|---|---|---|
| Uneven emergence | Seed distribution, crop-specific soaking requirements, uneven moisture | Correct the sowing process on the next tray before buying new equipment. |
| Long, weak or strongly leaning seedlings | Light distribution, long blackout period, crowding | Improve light placement and shorten unnecessary covered time. |
| Constantly wet medium | Drainage, excessive watering, standing water in the lower tray | Let excess water drain and water from actual moisture need. |
| Dry edges but wet centre | Uneven airflow or watering | Level the tray, distribute water more evenly, and avoid a fan aimed at one edge. |
| Suspected mould, slime or unpleasant odour | Excess moisture, dirty trays, poor airflow, contaminated material | For an edible crop, discard a suspicious batch rather than trying to “save” contaminated greens. Clean the tray before resowing. |
| Yellow or pale crop after moving into light | Light exposure, waterlogging, crop stage | Correct obvious environmental problems first; do not assume every pale seedling needs fertiliser. |
One useful habit is to change one variable per new tray. If you change seed density, medium, light height and watering method at the same time, you will not know which change mattered.
Food safety deserves its own checklist
Microgreens are eaten young and are often consumed raw. Warmth, moisture and dense plant stands are useful for growth but can also support unwanted microorganisms, so cleanliness belongs in the growing method.
For a home batch:
- wash hands before sowing and harvesting;
- use clean trays and clean scissors;
- use drinking-quality water;
- keep pets away from production surfaces;
- do not use visibly contaminated seed or growing medium;
- avoid leaving harvested greens warm and wet;
- refrigerate after harvest;
- wash in clean water before eating.
Penn State’s microgreens food-safety guidance emphasises clean water, worker hygiene and clean production surfaces for the same reason: food safety is not automatically guaranteed because a crop was grown indoors.
Should you buy a grow light for your first tray?
Not necessarily.
If one tray has a bright, practical position and grows evenly, learn the crop first. A light becomes useful when window light is inconsistent, the tray leans strongly toward one direction, you want repeatable year-round batches, or you are moving to shelves where natural light cannot reach the whole crop evenly.
When you do add a light, avoid choosing by wattage alone. Compare the size of the lit area, mounting space, controls and actual light distribution. For microgreens specifically, continue with the microgreens grow-light setup guide, which should remain TheOneGrow’s lighting-focused page.
Frequently asked questions
How long do microgreens take to grow indoors?
Many microgreens can be harvested within about 7–21 days, but that is a range rather than a promise. Species, seed condition, temperature, moisture and light all affect timing. Harvest by plant stage—developed cotyledons and emerging true leaves—rather than cutting every variety on the same numbered day.
Do microgreens need a grow light?
Not always. A bright window can be enough for a small hobby tray if the crop receives useful, even light. Grow lights become more valuable when natural light is inconsistent or when several trays are grown on shelves. Use the fixture’s real output and coverage rather than assuming one hanging distance fits every lamp.
How often should indoor microgreens be watered?
There is no reliable universal “once a day” rule. Check the growing medium and water when it needs moisture, not simply because the clock says so. After emergence, bottom-watering can help keep the canopy drier. Empty excess standing water and adjust for room temperature, airflow and tray depth.
Can I use ordinary potting mix for microgreens?
A clean, lightweight soilless potting mix can work well. Avoid dense garden soil indoors because it can drain poorly and is harder to manage hygienically. Coco-based media and suitable grow mats are alternatives. Whatever you choose, the key is even moisture with drainage rather than a permanently wet root zone.
Should I wash microgreens before storing them?
University extension guidance recommends washing microgreens in clean drinking water before eating, but wetting delicate greens can shorten storage life. A practical approach is to harvest clean, refrigerate them dry when appropriate, and wash close to the time you will eat them rather than storing them wet for days.
Do microgreens grow back after harvest?
Most microgreens are treated as a single-cut crop. Once the seedling is cut above the medium, reliable regrowth is limited and uneven. For a predictable second batch, clean the tray, prepare fresh or appropriately renewed growing medium, and sow another labelled crop rather than depending on regrowth.
Final takeaway
Learning how to grow microgreens indoors is mostly about repeatability: clean trays, even sowing, controlled moisture, useful light, airflow and clean harvest handling.
Start with one crop and one tray. Record what you did, then adjust one variable at a time. That approach gives you a reliable home routine without turning a simple edible crop into an equipment project.
If natural light is the weak point in your setup, move to the separate microgreens lighting guide and compare a compact shelf light only after you know the tray size and growing area you need to cover.