Growing microgreens indoors without soil is one of the simplest and healthiest ways to bring fresh greens into your home year-round. Microgreens are the young stage of edible plants such as broccoli, mustard, fenugreek, radish and peas.
They are ready to harvest in just 7 to 15 days and studies show they often contain higher levels of vitamins A, C, E and K compared to mature greens.
Because they are grown hydroponically or on soilless mats like hemp, coco coir or silicone, the process is clean, space-efficient and requires very little water. With only trays, seeds, light and a small amount of care, anyone can start growing nutrient-rich microgreens indoors without soil and enjoy a steady supply of fresh organic food.
Soilless Growing Mediums for Microgreens
Silicone mats
Reusable mats with fine mesh openings. Durable, easy to wash, and suitable for most seeds except very tiny varieties such as amaranth.
Paper towels or tissues
Single ply tissue works well for very small seeds. Keeps seeds in place until roots establish. Simple and inexpensive but single use.
Cotton pads or cotton lining
Absorbs and retains water well. Suitable for beginners using small containers. Breaks down quickly and usually not reusable.
Hemp mats
Biodegradable mats that wick water evenly. Popular in both home and commercial growing. Can be composted after use.
Natural fiber mats
Eco friendly mats made from plant fibers other than hemp or coconut. Compostable and provide consistent moisture.
Coco coir mats
Made from coconut husks. Excellent at holding water and maintaining root moisture. Require soaking before seeding.
Hydroponic water method
Seeds germinate on trays placed above a shallow reservoir of water. Roots grow directly into the water. Works best with good hygiene and pH management.
Structured hydroponic systems
Advanced options include Nutrient Film Technique, Deep Water Culture, Ebb and Flow, and Wick systems. These deliver nutrient rich water directly to the roots without any mat at all.
Essential Supplies for Soilless Microgreens
Containers and trays
The most common setup for indoor microgreens is a 10 by 20 tray system. One tray without holes serves as a reservoir while a tray with holes or mesh holds the growing medium. Another no hole tray can be placed on top to block light during the germination stage. If you do not have trays you can use food containers or cartons as long as there is a way to hold a small amount of water at the bottom.
Soilless growing mediums
Silicone grow mats are durable and easy to wash. Their mesh size of about one millimeter supports most seed types although very small seeds like amaranth can slip through. Paper towels or single ply tissue are often used for tiny seeds because they hold the seeds in place until roots anchor. Cotton can work in a similar way because it retains moisture.
Hemp mats are widely used for microgreens because they wick water evenly and are biodegradable. Natural fiber mats offer similar benefits and are compostable after harvest. Coco coir mats made from coconut husks are sustainable and hold water very well though they usually need a soak before use. For the simplest method you can even grow directly above water with no mat at all as long as the tray design keeps seeds moist until roots reach the reservoir.
Seeds for microgreens
Broccoli mustard fenugreek radish sunflower and peas are all reliable choices for indoor growing. Larger seeds such as peas and sunflower benefit from soaking overnight. A broccoli crop can be grown with about 20 grams of seed spread evenly on a 10 by 20 tray which equals roughly two tablespoons. The even spread of seed ensures good airflow and uniform growth.
Light for indoor microgreens
Bright indirect sunlight can work but consistent results come from grow lights. One effective indoor setup used three 20 watt LED bars to cover trays evenly. Move crops under light as soon as they leave the blackout stage. This keeps stems short strong and upright.
Water and nutrients
During the first days a light mist prevents seeds from bouncing on smooth mats and keeps the surface evenly moist. Once roots extend into the medium begin bottom watering. Some growers use plain water while others use a diluted nutrient solution balanced to a pH of 5.5 to 6.0. Always keep the water level below the top of the mat to avoid pooling.
Step by Step Growing Process Growing Mats Based
Seeding and setup
Prepare the tray with your chosen medium whether it is silicone hemp coco coir cotton or paper towel. Lightly mist the surface to hold seeds in place. Spread seeds evenly across the medium. If using the two tray water method fill the bottom tray with water until the top tray just touches it. Cover the seeded tray with another tray or lid and add a small weight to maintain darkness and humidity.
Germination phase
Check trays twice a day. Keep the medium evenly damp but not soaked. By the second day roots will appear. By the third day most seeds will be sprouting. A gentle mist once or twice a day is usually enough. The darkness created by the cover helps seeds sprout uniformly.
Blackout period
When most seeds have cracked and yellow shoots are pushing upward place the top tray upside down to create more headroom while still blocking light. This blackout stage usually lasts one to two days. Some growers add a small amount of water to the reservoir during this stage if conditions are dry.
Growth phase in light
When the canopy is standing tall remove the cover and move the trays to light. Begin bottom watering so roots pull up water and nutrients from the reservoir. Keep the surface from flooding to prevent mold. Rotate trays each day so plants grow straight. Provide airflow around the trays to reduce humidity buildup.
Harvest
Most crops reach harvest in 7 to 15 days depending on the type of seed and indoor conditions. Look for fully opened cotyledon leaves and the shedding of seed coats. Use scissors to cut greens about half an inch above the medium. Broccoli harvested on day 9 gave 95 grams from one tray seeded with 20 grams of seed. Always rinse harvested microgreens before eating since they are consumed raw.
🌿 Recommended Microgreens Supplies |
Hydroponic System Growing Process For Microgreens Step By Step
1. Choose the hydroponic approach
For microgreens you can keep it simple with a passive reservoir or scale up with a circulating setup. A passive tray system places a perforated tray above a shallow reservoir so roots reach moisture without any mat. Circulating systems include nutrient film technique where a thin stream of solution passes beneath roots, deep water culture where roots sit in an aerated reservoir, ebb and flow where trays are briefly flooded and drained, and wick systems that pull solution upward without pumps. Pick the style that matches your space and the number of trays you plan to run.
2. Prepare trays and surfaces
Clean all parts with warm water and a food safe soap. Rinse well and let them dry. If you are using a perforated seed tray above a reservoir, confirm the top tray will touch the water surface once filled but will not sit underwater. If you are using channels for nutrient film technique or net pots for deep water culture, ensure tight fits so seeds and young roots do not slip through openings.
3. Mix nutrient solution and set pH
Fill the reservoir with fresh water and then add a mild hydroponic nutrient according to the label for leafy seedlings. Set pH in the range that repeatedly worked well in practice which is between 5.5 and 6.0. This range supported fast, even growth during bottom watering and hydroponic runs. Keep the solution level low enough that the seed surface will not pool.
4. Seed preparation and density
Soak larger seeds such as peas or sunflower overnight. Most small seeds can be used dry. Spread seed evenly so the surface forms a single uniform layer without piles. A practical reference is broccoli at about 20 grams of seed on a standard 10 by 20 tray which is roughly two tablespoons. Even coverage improves airflow and leads to a level canopy.
5. Sow and create initial humidity
Mist the sowing surface lightly so seeds settle and stay put. After seeding, mist again so the seed coats are uniformly damp. Cover the tray with an empty tray or lid and add a small weight. This traps moisture and keeps light out which speeds uniform sprouting. Place the tray in a dark spot.
6. Germination checks
Check moisture morning and evening. Seeds swell on day one and the first root usually appears by day two. Continue light misting if the surface begins to dry. Avoid puddles. In a reservoir based setup you can top up with a small amount of water if the level drops below contact.
7. Short blackout
When the surface shows widespread cracking seed and pale emerging shoots, flip the cover so it sits higher and still blocks light. This short blackout usually lasts about a day. The goal is strong upright stems before moving to light.
8. Move to light and start hydroponic flow
Uncover the tray and place it under bright indirect light or LEDs. A proven arrangement used three 20 watt LED bars over the grow area and produced reliable results for seasons. Begin your chosen hydro routine.
For nutrient film technique start a thin continuous film of solution along the channel floor.
For deep water culture start aeration so the reservoir gently bubbles beneath the roots.
For ebb and flow set a short flood every few hours and let the tray drain completely between cycles.
For wick systems confirm wicks are fully saturated and can keep the root zone consistently moist.
In passive reservoir trays begin bottom watering with the nutrient solution so roots drink from below while the surface stays dry.
9. Daily care
Rotate trays once a day so stems grow straight. Keep gentle airflow around the crop to discourage excess humidity. Maintain the pH close to 5.5 to 6.0 and keep solution fresh. Top up with fresh solution as plants drink and avoid filling so high that the surface becomes wet. If the room is dry a small addition of water in the bottom tray during blackout or early light days helps maintain steady moisture.
10. Harvest timing and yield reality
Most microgreens reach harvest between day seven and day fifteen depending on the crop and room conditions. Cues include open cotyledons, seed coats dropping, and an even stand. Cut with clean scissors about half to one inch above the surface. Rinse in cool water before eating. A real world reference is broccoli grown indoors on a reusable mat and managed with bottom watering that produced about 95 grams from a single 10 by 20 tray in nine days using 20 grams of seed.
11. Cleanup and reset
Remove roots and hulls from trays. Rinse parts in hot water and wash with a food safe soap. Rinse well and dry completely. Refill with fresh solution before the next sowing. For larger or repeated runs add a sanitizing step that aligns with local guidance.
Quick Start Guides For Each Hydroponic Style
Nutrient Film Technique
Set channels with a slight slope. Prime the system with nutrient solution and adjust pH to 5.5 to 6.0. Place a perforated liner or net pot inserts so seeds cannot fall through. Sow evenly and cover for darkness. After sprouting run a gentle continuous flow that just kisses the root tips. Keep the film thin rather than filling the channel.
Deep Water Culture
Place net pots or a perforated tray above an aerated reservoir. Adjust pH to 5.5 to 6.0. Sow on small liners or on a fine support so seeds do not fall into the water. After sprouting keep air stones running so roots receive constant oxygen. Maintain a gap between the water surface and the seed surface to prevent saturation.
Ebb And Flow
Place the sowing tray on a table with a drain back to the reservoir. Adjust pH to 5.5 to 6.0. Sow and cover. After sprouting start short floods that rise to just below the seed surface and then drain fully. Begin with two to three short floods per day and adjust with room temperature and plant uptake.
Wick Systems
Run cotton or synthetic wicks from the reservoir into the tray. Adjust pH to 5.5 to 6.0. Pre wet the sowing surface and wicks, then sow and cover. After sprouting keep the reservoir filled and confirm wicks remain saturated. This is a good low energy choice for a few trays.
Passive Reservoir Tray
Use a no hole tray for water and a perforated tray for seeds. Fill so the top tray barely touches the water. Sow and cover. After sprouting move to light and keep bottom watering so the surface stays dry while roots drink from below. This mirrors the simple kitchen method and aligns with the moisture management that worked well across multiple crops.
Cleaning and Reuse
Post harvest practices
After harvest remove leftover roots and seed hulls. On silicone mats you can peel clumps of roots away or use a scraper tool. Rinse with hot water and then wash with food safe soap. Rinse again and allow the mat to dry fully before reuse. For larger operations an added sanitizing step is advised.
Single use and compostable mediums
Paper towel cotton and many natural fiber mats are designed for single use. These can be composted after harvest. Hemp mats and some coco coir mats can be reused for a limited time depending on their thickness and strength but are often composted as well. Always wash trays thoroughly with warm water and mild soap before planting again.
Comparison of Soilless Mediums and Hydroponic Systems
Silicone reusable mats
Silicone mats are long lasting and easy to clean. They provide clear visibility for seed distribution and support most seed sizes. They are more costly up front but one mat can be reused many times. In a tested broccoli grow a silicone mat produced a consistent harvest of 95 grams in nine days under LED lighting.
Paper towels and tissue
These are inexpensive and ideal for small seeds and quick trials. A single ply layer is enough to hold seeds in place. They must stay evenly moist until roots grow through. The main drawback is that they are single use and dry out easily if not monitored.
Cotton
Cotton retains moisture well and is widely available at home. It can however decompose quickly and become messy if water levels are not managed. Like tissue it is best for small scale or experimental grows.
Hemp mats natural fiber mats and coco coir mats
Hemp mats are biodegradable and hold water evenly which makes them popular for both home and commercial growing. Natural fiber mats serve a similar role and can be composted after use. Coco coir mats come from coconut husks and hold moisture strongly which is useful in dry climates. They usually require soaking before seeding.
Hydroponic water and structured systems
Some growers skip mats entirely and allow seeds to sprout over water using a two tray setup. For larger harvests structured hydroponic systems can be used. Nutrient film technique provides a thin stream of solution under roots. Deep water culture suspends roots in aerated nutrient solution. Ebb and flow systems flood and drain trays on cycles. Wick systems pull solution up passively into the root zone. These methods often speed growth and increase yields but require attention to pH and nutrient balance. A pH range between 5.5 and 6.0 worked well in successful trials.