Growing microgreens is simple but getting them to grow healthy and strong starts with one key choice: the growing medium. Pick the wrong one and you might face patchy growth, poor roots, or weak yields.
Pick the right one and your greens will thrive with vibrant color, rich flavor, and sturdy roots. From nutrient-packed soils to low maintenance hydroponic mats and sleek silicone trays, the options are plenty.
This guide breaks down the best growing mediums based on real experiments and honest results. What works for strong, healthy microgreens from the very first sprout to the final harvest 🌱💧🌿
Criteria for Selecting a Microgreen Growing Medium
Choosing the best medium for microgreens requires evaluating several factors that directly affect plant health, operational ease, and product quality.
Nutrient Availability
Some mediums, like high-quality soils or compost blends, come with naturally embedded nutrients that feed microgreens throughout their short life cycle. In contrast, inert options like silicone grow mats or coco coir provide minimal or no nutrients and rely on added liquid fertilizers. Soil provides a “nutrient boost just before harvest,” which can enhance flavor, size, and nutritional value.
Water Retention Capacity
Microgreens require a moist but not saturated environment. A good medium should retain enough water to hydrate roots without causing oversaturation. Soil holds water longer than synthetic grow mats, which tend to dry out more quickly. Coco coir, as noted in the test, maintains moisture well while avoiding sogginess, making it a popular soilless option.
Airflow and Drainage
Healthy roots need access to oxygen. A good growing medium provides “pore space,” or tiny pockets of air, for root respiration. Both soil and coco coir exhibit this trait, which helps reduce disease and promote strong root systems. Compacted or poorly draining mediums can lead to damping off and root rot, common issues for microgreens.
Pathogen Resistance
The risk of pathogens like mold and mildew can derail entire trays of microgreens. According to the soil vs. grow mat video, high-quality compost and proper airflow can suppress disease naturally. On the other hand, grow mats are often preferred in environments where “clean harvest” and “no soil debris” are priorities, such as restaurants, due to their sterile nature.
Ease of Use and Cleanup
Grow mats and silicone trays score high in convenience. They’re clean, lightweight, and easy to store. Soil, while offering high yields, can be messy to work with and requires more time for tray preparation and post-harvest cleanup. DIY mixes must be carefully blended and pH-adjusted if using peat moss.
Cost and Accessibility
Soil is generally the cheapest and most accessible growing medium, especially when components are locally sourced. Fiber or synthetic grow mats, although convenient, are more expensive per tray and often single-use. The video notes that soil “is significantly cheaper than buying fiber or synthetic grow mats.”
Environmental Sustainability
Coco coir is considered a renewable resource and more eco-friendly than peat moss, which is harvested from slow-regenerating bogs. Reusable silicone mats offer a long-term sustainable option with no waste generation if properly maintained. Soil, while biodegradable and compostable, may still require responsible sourcing of ingredients like peat or compost.
Selecting the right growing medium is ultimately a balance between your growing goals, your budget, and your available infrastructure.
Top Growing Mediums for Microgreens
Microgreens can grow successfully on a variety of mediums, each suited to different setups and goals. Four mediums stand out due to their proven effectiveness and practical advantages: soil-based mediums, coco coir, silicone grow mats, and fiber grow mats.
These growing mediums are evaluated based on multiple factors such as nutrient delivery, growth rate, ease of use, disease resistance, and overall yield. Experimental data taken from a side-by-side test using the same seeds across three growing mediums—soil, coco coir, and silicone—provides clear insights into their performance.
In this test, trays were sown with equal amounts of seeds, using different substrates. The Ocean Forest potting soil outperformed both coco coir and silicone in yield and early-stage growth. However, silicone showed better cleanliness and reusable benefits, while coco coir offered a middle ground in terms of ease and efficiency.
Let’s examine each of these mediums in depth to understand their strengths, weaknesses, and best-use cases.
Soil-Based Mediums
Soil remains the most traditional and, in many cases, the most effective growing medium for microgreens. It’s nutrient-rich, holds moisture well, provides strong root anchorage, and allows for biological activity that supports healthy plant development.
The Ocean Forest potting mix, was particularly effective. Microgreens grown in this soil germinated as early as Day 3 and reached a total yield of 86.5 grams per tray by Day 11. That’s a significant difference compared to the 45.7 grams from coco coir and 30 grams from silicone mats, making it the best performer in the test.
Soil offers multiple advantages:
- It supports biological activity, which can naturally suppress pathogens.
- It contributes to better flavor and appearance. The Modern Grower video emphasizes that many growers feel soil-grown microgreens are “better tasting and better looking.”
- It’s compostable, meaning post-harvest waste can be reintegrated into your garden or compost pile.
- It allows for flexible tray depths and shapes.
Ready-made soils like Ocean Forest, Sunshine Mix #4, and Happy Frog are good starting points. These mixes typically include components like peat, perlite, compost, and trace minerals, delivering a well-rounded environment for seedlings.
Alternatively, growers can create a DIY mix:
- 70–75% coconut coir or peat moss for water retention and root support.
- 20–25% perlite or vermiculite for aeration and drainage.
- 5–10% finished compost to provide nutrients.
One important note: peat moss is acidic, with a naturally low pH. If using peat, balance the pH by adding agricultural lime to neutralize acidity. Maintaining a pH close to 6.0–6.5 is ideal for most microgreens.
While soil does have downsides—such as added weight, risk of soilborne diseases, and post-harvest mess—it remains the top choice for growers prioritizing yield, taste, and plant health. When paired with good airflow and bottom watering techniques, it can outperform other mediums consistently.
Coco Coir
Coco coir is a byproduct of coconut fiber processing and has become one of the most popular soilless growing mediums for microgreens. Its appeal lies in its excellent water retention, natural resistance to pests, and renewable sustainability compared to peat-based products.
Coco coir showed moderate performance. By Day 3, seeds had germinated, and by Day 11, the tray yielded 45.7 grams, making it the second-best performer after soil. Visually, the coir-grown microgreens had good color and consistent growth, though slightly smaller than their soil-grown counterparts.
Benefits of Coco Coir for Microgreens:
- High Water Retention: Coco coir absorbs and holds moisture without becoming waterlogged. This creates a consistent moisture level at the root zone.
- Aeration and Drainage: The fibrous structure allows ample air pockets, which help roots breathe and reduce the likelihood of rot.
- Neutral pH: Most commercial coco coir is buffered to a neutral pH of 5.8–6.5, ideal for most microgreens.
- Clean and Easy to Handle: Coir is light, mess-free, and often pre-packaged in compressed blocks, which expand when hydrated.
- Sustainable Choice: As a coconut industry byproduct, it’s considered more eco-friendly than peat moss, which is slow to regenerate.
However, coco coir is nutrient-inert. It does not contain natural nutrients, so growers must supplement with liquid fertilizer or compost teas if they aim for higher yields or longer growth cycles. In short cycles like microgreens (under 14 days), nutrient supplementation is not always required, but it can enhance results.
Application Tips:
- Use a high-quality, pre-buffered coir to avoid issues with excess salts.
- Avoid overpacking coir in trays, which can restrict air and root development.
- Ensure proper drainage, especially if you’re rehydrating compressed bricks with warm water.
Coco coir is an excellent middle-ground option—cleaner and lighter than soil, yet capable of better root support and water retention than grow mats.
Silicone Grow Mats
Silicone grow mats represent a modern and reusable solution for clean microgreen production, especially suited for small-scale growers or indoor kitchen setups.
Despite being innovative and eco-conscious, silicone grow mats yielded only 30 grams by Day 11 in the head-to-head test. That’s less than half of the soil-grown tray’s output. Still, they offer notable advantages that make them attractive for niche use cases.
Advantages of Silicone Mats:
- Reusable and Durable: Unlike hemp or jute mats, silicone can be washed and reused hundreds of times, reducing long-term costs and environmental impact.
- Cleanliness: Ideal for chefs, kitchens, or consumers wanting a soil-free experience. There’s no risk of soil or compost debris contaminating food preparation areas.
- No Need for Tray Fill: Since they are cut to size, you just place the mat in a tray and seed directly on top, significantly cutting down setup time.
- Space-Saving and Lightweight: These mats don’t bulk up storage space and trays are easier to move.
Limitations:
- Lower Water Retention: Silicone doesn’t hold moisture well by itself, requiring more frequent watering or a wick system underneath.
- Zero Nutrients: Like most non-soil mediums, silicone provides no nutrition, so regular foliar feeding or nutrient-rich water is a must for robust growth.
- Weaker Root Anchorage: Root systems may not anchor well on smooth silicone, potentially resulting in uneven growth or falling plants during harvesting.
In practice, growers often combine silicone mats with bottom trays or even place paper towel underlays to help manage moisture. If maintained properly, they are a clean, reusable option especially useful for growing smaller or sticky-seed varieties like arugula or broccoli.
Other Grow Mats (Hemp, Jute, Synthetic)
Beyond silicone, several other grow mats dominate the microgreens space. These include natural fiber mats such as hemp and jute, as well as synthetic polymer mats often used in commercial hydroponic operations.
Hemp Mats:
- Made from natural hemp fibers compressed into sheets.
- Offer decent water retention and are biodegradable.
- Require a tray with drainage as they can become too saturated, leading to mold issues if overwatered.
- Expensive per tray, especially for single-use applications.
Jute Mats:
- Derived from jute plant fibers and are also biodegradable.
- Known for their firm structure and ability to hold seeds in place.
- Similar to hemp in terms of water retention and cost.
Synthetic Mats:
- These include polyester blends, polyurethane foams, and other synthetic fibers.
- Designed for hydroponic environments, with excellent water dispersion and uniformity.
- Non-biodegradable but reusable if cleaned and sanitized properly.
- Some commercial growers prefer them due to their consistent behavior and pathogen resistance.
As mentioned in the Soil vs. Grow Mats video, one clear benefit of grow mats (natural or synthetic) is their clean harvest potential. There’s “no risk of soil debris,” and chefs prefer them for live tray harvests directly in the kitchen.
However, they generally lack nutrients, require additional inputs, and are costlier in the long term unless reused multiple times. Growers using mats often need to add nutrients to the water supply, increasing input costs and operational complexity.
Hydroponic Methods (Water Only Systems)
In some experimental and high-tech growing setups, microgreens are grown hydroponically using only water and nutrient solution, without any substrate. This is usually achieved using floating trays, mesh baskets, or sprouting jars.
While not as common, these systems are appealing for ultra-clean production and space-saving vertical farms.
Advantages:
- Zero Soil or Media Costs: There’s no need to buy or dispose of substrate.
- Highly Controlled Environment: Ideal for automation and nutrient precision.
- Fast Growth: If nutrient levels, pH, and oxygenation are managed well, plants can grow quickly and uniformly.
Challenges:
- Fragile Roots: Without anchorage, roots can float or twist, causing inconsistent growth.
- Nutrient Management: Since the medium is just water, constant monitoring of EC (electrical conductivity) and pH is necessary to avoid deficiencies or toxicity.
- Limited Varietal Suitability: Heavier microgreens like sunflower or peas don’t perform well in these systems due to poor root support.
Hydroponic systems for microgreens are best used in controlled environments like automated vertical farms or for growing lightweight crops like broccoli, arugula, and radish, where clean roots and rapid cycles are desired.
Comparative Analysis: Yield, Taste, and Efficiency
To make a practical decision, growers need to assess how each medium performs in terms of yield, taste, ease of use, cost, and cleanliness. How these media compare:
| Growing Medium | Yield (grams) | Taste & Appearance | Water Retention | Cleanliness | Cost Efficiency | Notes |
|---|---|---|---|---|---|---|
| Soil | 78.8 | Excellent (vibrant, full flavor) | High | Low (messy harvest) | High (cheap & local) | Best overall performance |
| Coco Coir | 45.7 | Good (slightly milder than soil) | High | Medium | Medium | Cleaner than soil, reusable trays |
| Silicone Mats | 30.0 | Decent, less uniform | Low | High (very clean) | Medium-High (reusable) | Ideal for indoor/kitchen use |
| Grow Mats (Hemp/Jute/Synthetic) | Varies (30–50 est.) | Varies (depends on nutrition added) | Medium | High | Medium-Low (usually single use) | Good for hydroponic + chef use |
| Hydroponic (Water Only) | ~25–35 est. | Light flavor, small size | None (constant monitoring needed) | Very High | High (no media cost) | Demands precision & tech |
Key Takeaways from the Test:
- Soil outperformed all other media by a significant margin (by at least 33 grams), with the best root anchorage, full tray coverage, and strong taste.
- Coco coir came in second and offered a great compromise between cleanliness and performance, especially for those avoiding soil mess.
- Silicone mats delivered lower yields but excelled in reusability and clean harvesting, making them suitable for kitchen growers or hobbyists.
- Grow mats (natural or synthetic) have variable results depending on the seed type, tray setup, and nutrient supplementation. Their appeal lies in cleanliness and convenience.
Taste is often subjective, but many growers, including the speaker in the Soil vs. Grow Mats video, report that soil-grown microgreens have better color, stronger stems, and superior flavor—likely due to the natural nutrients and biological activity in soil.
Recommendations Based on Your Goals
Microgreen growers come with different objectives—some prioritize yield, others want minimal cleanup, and some want the most sustainable or cheapest option. Here’s a breakdown based on different grower profiles:
For Maximum Yield and Flavor (Professional Growers, Farmers’ Markets)
- Best Choice: High-quality organic soil mix
- Why: Highest yield, strongest root support, rich taste, best color uniformity
- Tip: Use shallow trays and sifted mix for better seed-to-soil contact. Try recipes like 70% coco coir or peat moss + 20% perlite + 10% compost for custom blends.
For Clean, Soil-Free Growing (Chefs, Indoor Kitchens, Apartment Growers)
- Best Choice: Silicone mats or synthetic grow pads
- Why: Clean harvest, reusable or disposable, no soil contamination
- Tip: Add foliar nutrients or OceanSolution to improve performance. Good airflow and light are critical to compensate for nutrient-free media.
For Budget-Conscious Growers
- Best Choice: DIY soil mix using local compost, coco coir, and perlite
- Why: Economical, customizable, and easy to find
- Tip: Avoid large wood chunks or clumps in compost. Add agricultural lime if using peat moss to balance pH.
For Sustainable/Environmentally Friendly Growers
- Best Choice: Coco coir or biodegradable hemp/jute mats
- Why: Renewable, compostable, and lower environmental impact than peat-based or synthetic options
- Tip: Choose buffered, low-salt coir and avoid overwatering to reduce disease risk.
For Experimental or Hydroponic Setups
- Best Choice: Water-only systems or reusable synthetic mats
- Why: Great for automated systems or clean vertical farms
- Tip: Invest in pH and EC meters to maintain optimal nutrient solution conditions.
Key Takeaways
Choosing the right growing medium for microgreens is a balance between yield, cleanliness, cost, sustainability, and grower goals. Based on authentic testing and grower feedback:
- Soil is the undisputed leader for yield, flavor, and plant health. It’s versatile and cheap, making it ideal for most growers.
- Coco coir offers a cleaner and more sustainable alternative to soil, though yields may be lower.
- Silicone mats and grow pads provide clean harvests and are ideal for indoor setups, but generally produce smaller crops.
- Hydroponics is possible but best suited for controlled environments with nutrient management.