Stainless Steel Reusable Microgreen Grow Medium: Complete Guide and Why We Transitioned to Silicone

(Editor's note, May 2026: We no longer sell the 10x20 stainless steel reusable grow medium as of 2024, and we are phasing out the remaining 10x10 and small sprouting tray sizes. Our current flagship reusable grow medium is our food-grade silicone reusable grow medium, which most of our customers (and us) prefer for its flexibility, lack of sharp edges, lighter weight, and ease of use. This blog is kept up for educational purposes and for anyone who already owns the stainless steel version. If you're shopping new, head to our silicone reusable grow medium blog instead.)

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What is a reusable microgreen grow medium? As the name suggests, it is a medium that can be used multiple times, offering cost savings over time with a single initial investment. Unlike reusable cups, straws, or bags, this medium is specifically designed for hydroponic growing. It serves as a lattice for plant seeds, providing support as they germinate and anchoring the root structures as the plants develop.

These reusable grow mediums can be more environmentally friendly because you aren't buying bags of soil, coco coir, or other hydroponic grow mats that generally come wrapped in plastic, shipped all around the country, and needed in large quantities to only be used once per grow. You could compost your coco coir or soil after growing microgreens on it and reuse it again, but the sterilization and composting process can be tedious when compared to simply cleaning off a reusable medium and starting again.

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Quick Answer: What Is the Stainless Steel Reusable Grow Medium?

The stainless steel reusable microgreen grow medium is a 316-grade stainless steel mesh designed to replace single-use grow mediums like soil and coco coir. We launched it in 2021 and it remained popular for several years, but we no longer sell the 10x20 size as of 2024 and are phasing out the remaining 10x10 and small sprouting tray sizes. Our current recommendation for new growers is the food-grade silicone version, which offers similar reusability with the added benefits of flexibility, no sharp edges, lighter weight, and easier handling.

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Why We Transitioned Away From Stainless Steel

The stainless steel reusable medium served us well for years, and it's still a solid option for anyone who already owns one. That said, after years of growing on both stainless steel and silicone side by side, we (and most of our customers) consistently preferred the silicone for several reasons:

• No sharp edges. Stainless steel mesh has sharp edges that can cut hands during handling, cleaning, and storage. Silicone is soft and flexible with no risk of cuts.
• Lighter to ship. Stainless steel is heavy, which made shipping costs higher for both us and our customers.
• Easier on the hands during cleanup. Removing root debris from stainless steel is workable, but the same cleanup on silicone is significantly faster and gentler on your hands.
• More flexible for different tray fits. Silicone bends and conforms to tray edges easily. Stainless steel is rigid and needs to be cut with metal scissors if it doesn't fit.
• Third-party tested and FDA compliant. Our 1.2mm silicone reusable grow medium is third-party tested and FDA compliant per 21 CFR 177.2600, LFGB Tested & Compliant. It's virgin food-grade platinum-cured silicone with a fiberglass mesh core, rated for 20 to 30+ growing cycles.

If you'd like to learn more about the silicone version, head over to our silicone reusable grow medium blog or our seed compatibility guide for reusable mediums.

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For Those Who Already Own the Stainless Steel Medium

If you already own our stainless steel reusable grow medium, this blog will help you get the most out of it. The information below on seed compatibility, cleaning, sanitizing, and storage all still applies. With proper care, your stainless steel medium will continue to last for many grows. The same growing methods and seed compatibility apply to both the stainless steel and silicone versions, so any video showing us growing on silicone will translate directly to stainless steel.

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About Our Stainless Steel Reusable Grow Medium

When we sold the stainless steel version, it was crafted from high-quality 316-grade stainless steel, which offered durability and corrosion resistance, making it a strong choice for hydroponic setups. Here's a quick glance at what made the stainless steel medium stand out:

Feature	Stainless Steel Grow Medium	Traditional Grow Mediums
Material	316-grade stainless steel	Plastic, coco coir, soil
Durability	High (reusable for hundreds of grows)	Low to medium
Environmental Impact	Low (reduces waste significantly)	High (frequent replacements)
Ease of Cleaning	Medium (easy to sanitize and reuse)	Low (can be labor-intensive)
Seed Compatibility	High for most seeds, challenges with tiny seeds like amaranth	No seed limitations

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Comparison of Reusable Grow Mediums

Here's how the stainless steel and silicone versions of our reusable grow mediums compare. For new growers, we recommend the silicone version.

Feature	Stainless Steel Grow Medium	Silicone Grow Medium	Traditional Grow Mediums
Material	316-grade stainless steel	Virgin food-grade platinum-cured silicone with fiberglass mesh core	Plastic, coco coir, soil
Durability	High (reusable for hundreds of grows)	Rated for 20 to 30+ growing cycles (1.2mm), designed to last for years	Low to medium
Compliance & Certification	316-grade stainless, food-safe	FDA compliant per 21 CFR 177.2600, LFGB Tested & Compliant (1.2mm)	Varies by source
Environmental Impact	Low (reduces waste significantly)	Low (reduces waste, sustainable)	High (frequent replacements)
Ease of Cleaning	Medium (easy to sanitize but heavier to handle)	High (easy to clean, dishwasher-safe)	Low (can be labor-intensive)
Seed Compatibility	High for most seeds, challenges with tiny seeds like amaranth	1.2mm for most seeds, 1.7mm for larger seeds like peas and sunflower	Works for most seeds
Initial Investment	Higher (no longer sold by On The Grow)	Higher but pays for itself after a few uses	Lower but requires continuous purchase
Flexibility and Handling	Rigid, sharp edges require careful handling	Flexible, soft, no sharp edges, easy to handle	Varies depending on material
Shipping Weight	Heavier	Significantly lighter	Varies

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Environmental Impact and Long-Term Savings

Using a reusable grow medium of any type (stainless steel or silicone) offers significant environmental benefits and long-term savings compared to single-use mediums. Reusable mediums are highly durable and can be reused many times, depending on how you care for them, reducing the waste generated by frequent replacements. This longevity minimizes the need for manufacturing new grow mediums, which can contribute to conserving resources and reducing carbon emissions associated with production and transportation.

For 316-grade stainless steel specifically, it is fully recyclable at the end of its life cycle, ensuring it does not contribute to landfill waste. This type of stainless steel, which contains molybdenum in addition to chromium and nickel, is known for its enhanced corrosion resistance and is widely used in various applications where durability and longevity are critical. Like other types of stainless steel, it does not lose its properties during the recycling process, allowing it to be recycled indefinitely without degradation in quality.

Indirect savings are another key advantage. By investing in any reusable grow medium, growers can save money over time by eliminating the need for constant replacements. The initial cost may be higher, but the long-term savings on purchasing new grow mediums and the reduction in waste disposal fees make it a cost-effective choice.

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History of Our Reusable Microgreen Grow Medium

In 2021, we launched the Reusable Microgreen Grow Medium (RMGM), alongside our  Microgreen Tray Clip Labelers. The original RMGM was constructed from 316-grade stainless steel, known for its corrosion resistance, making it well-suited for use with acidic hydroponic nutrients like our recommended Ocean Solution 2-0-3 (mixed at 0.5 oz per gallon, pH 5.5 to 6.0). The durability of stainless steel was a significant advantage, designed to withstand hundreds of growing cycles without the common issues faced with plastic meshes, such as damage from cutting tools or tearing during cleaning.

The stainless steel RMGM featured a mesh density of 1mm, which prevented most microgreen seeds from slipping through. Finer seeds like amaranth and sorrel could fall through when sown directly onto the mesh. The same general seed compatibility applies to our current silicone reusable grow medium, with the 1.2mm standard silicone working for most varieties and the 1.7mm large-hole silicone for larger seeds with aggressive roots like peas and sunflower.

For crops like arugula or clover, we advise first misting the medium with a light pass of water prior to seeding. This will help the seeds stick for germination. Once seeded, water as usual.

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Which Seeds Work With Reusable Grow Mediums

The seed compatibility below applies to both our stainless steel (mesh density 1mm) and our silicone (1.2mm standard, 1.7mm large-hole) reusable grow mediums. For the most current and detailed seed compatibility guidance, see our dedicated seed compatibility guide for reusable grow mediums.

Compatible Seeds

Microgreen seed varieties that work well with reusable grow mediums. Through hands-on testing, we've found that medium to larger seeds with manageable root systems perform best on reusable grow mediums. These include a wide range of brassicas, herbs, and salad greens.

Broccoli varieties: Waltham 29, Di Cicco, Purple Sprouting, Calabrese Green, Ramoso Santana
Radish varieties: Rambo, Daikon Minowase, China Rose, Triton Purple, Sango Purple, Red Arrow, Purple Plum, Hong Vit, Purple, Colorful Radish, Confetti Mix
Kale varieties: Red Russian, Vates Blue Scotch Curled, Black Tuscan (Lacinato), Dwarf Siberian, White Russian, Bright Green Curly, Purple Reign, KX-1, Unicorn, Kalefetti Mix, Red Kale
Cabbage and Pak Choi varieties: Red Acre, Mammoth Red Rock, Golden Acre, Glory of Enkhuizen, Pak Choi White Stem, Red Pak Choi
Mustard and Asian greens: Spicy Oriental, Mizuna, Mizuna Red, Tatsoi, Red Tatsoi, Komatsuna (Spinach Mustard), Mizuna Red Kingdom
Other brassicas: Kohlrabi Purple Vienna, Kohlrabi Early White Vienna, Brussels Sprouts Long Island Improved, Turnip Purple Top White Globe, Rutabaga American Purple Top, Collards Vates, Cauliflower Snowball Y Improved, Cauliflower Igloo
Basil varieties: Genovese, Italian Large Leaf, Dark Opal, Bicolor, Colorful Basil Mix, Lemon Basil
Additional compatible varieties: Arugula Slow Bolt, Arugula Astro, Curled Cress, Fenugreek, Purslane, Red Gruner, Chia, Red Clover, Crimson Clover
Seed mixes: Basic Salad Mix, Spicy Salad Mix, Mild Micro Mix, Superfood Mix
Sunflower: Black Oil Sunflower

Seeds That Require Special Consideration

Best grown without a medium (mesh tray only). Pea varieties have aggressive root systems that tend to tangle deeply into reusable grow mediums, making removal difficult. These varieties perform best when grown directly on a mesh tray without any medium. See our pea microgreens growing guide for full instructions.

Pea varieties: Dun, Green (Organic), Speckled, Afila Tendril, Yellow, Thomas Laxton, Early Frosty, Yellow Sugar, Snow (Dwarf Sugar Grey)

Seeds Not Suitable for Reusable Grow Mediums

Too small for the mesh. Very fine seeds can fall through the mesh openings of reusable grow mediums (though we've had success with amaranth on the 1.2mm silicone when using a heat mat at 75°F during germination).

Tiny seed varieties: Amaranth Red Army, Amaranth Red Garnet, Amaranth Bicolor, Amaranth Glitter Mix, Red Veined Sorrel, Celosia, Wasabina Mustard

Germination preference for soil or coco coir. These varieties have germination requirements that do not perform well on reusable grow mediums.

Soil-preferred varieties: Beet Detroit Dark Red (Conventional), Beet Detroit Dark Red, Beet Bulls Blood, Beet Rainbow Blend, Swiss Chard Ruby Red, Swiss Chard Rainbow Mixture, Swiss Chard Pink Lipstick, Swiss Chard Yellow, Swiss Chard Barese Dark Green Smooth Leaf, Chard and Beet Rainbow Sprinkles Mix, Cilantro Slow Bolt, Cilantro Leisure Splits, Fennel Florence, Buckwheat, Borage, Nasturtium Jewel Mix, Nasturtium Alaska, Marigold

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Cleaning and Sanitizing Stainless Steel Reusable Grow Medium

If you already own a stainless steel medium, here's how to keep it in top condition for years of grows.

Step 1: Remove Microgreen Leftovers

Once you have harvested your microgreens, use our Microgreen Medium Scraper to remove the stems and roots from the medium. This process usually only takes 30 seconds to 1 minute with our handy tool.

Step 2: Pre-Clean

Before sanitizing, remove any plant debris or soil by gently scrubbing with a soft cloth or your hands under running water. This helps ensure the sanitizer can contact all surfaces directly. Do not use metal or abrasive brushes, as these can create micro-scratches that harbor bacteria.

Step 3: Wash

Use a mild, scent-free detergent and warm water to thoroughly clean the surface. A soft cloth or sponge is ideal to avoid scratching the metal. After washing, rinse the stainless steel thoroughly with clean water to remove any soap residue.

Step 4: Sanitize

You have several food-safe options for sanitizing:

• Hydrogen peroxide: Spray or soak with standard 3% food-grade hydrogen peroxide for 10 to 20 minutes. No rinsing needed since hydrogen peroxide breaks down into water and oxygen.
• Heat: Boil the stainless steel medium in a pot of water for at least 5 minutes, or use a steam sanitizer if available. Use tongs to handle hot metal.
• Chemical sanitizer: A diluted bleach solution (around 1 tablespoon of bleach per gallon of water) can also work. Rinse thoroughly after.
• UV light: UV sterilization is another effective method if you want to avoid chemicals. Place the stainless steel under a UV light for the prescribed amount of time to kill lingering pathogens.

For a deeper dive into sanitation methods, see our how to clean and sanitize microgreen trays and reusable mediums blog.

Step 5: Dry

Allow the stainless steel to air dry completely or use clean towels. Moisture can promote bacterial growth, so it's important the surface is dry before storage or reuse.

Step 6: Storage

Keep the stainless steel in a clean, dry place away from direct sunlight and dust when not in use. Store flat to maintain shape and extend lifespan.

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When to Replace 316-Grade Stainless Steel

• Corrosion or pitting: Although 316-grade stainless steel is highly resistant to corrosion, exposure to harsh chemicals over a long period can cause pitting or corrosion. If you notice these signs, it's time to replace the item.
• Surface degradation: Any cracks, deep scratches, or rough surfaces can harbor bacteria and make complete sanitation difficult. These are signs the stainless steel should be replaced.
• Structural weakness: If the metal becomes bent or warped to the point that it no longer fits properly or can't hold materials securely, it should be replaced.

Since we no longer sell the stainless steel version, when it comes time to replace yours, we recommend switching to our silicone reusable grow medium.

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Pros and Cons of Stainless Steel Reusable Microgreen Grow Medium

Advantages	Disadvantages
Extremely durable, 50+ grows	Sharp edges pose a handling risk
Made from corrosion-resistant 316-grade stainless steel	Heavier to ship and handle
Highly recyclable at end of life	Rigid, requires metal scissors to resize
Easy to sanitize	No longer sold by On The Grow

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Frequently Asked Questions

Do you still sell the stainless steel reusable grow medium?

We no longer sell the 10x20 size as of 2024, and we're phasing out the remaining 10x10 and small sprouting tray sizes. Our current flagship reusable grow medium is our food-grade silicone reusable grow medium, which most of our customers prefer.

Why did you stop selling the stainless steel version?

After years of using both stainless steel and silicone side by side, we (and most of our customers) consistently preferred the silicone version. The silicone has no sharp edges, is significantly lighter to ship, is easier to handle, and is third-party tested and FDA compliant and LFGB Tested & Compliant. The stainless steel served us well, but the silicone is the better fit for how most people actually grow.

Can I still use my stainless steel medium?

Absolutely. If you already own one, it will continue to last for 50+ grows with proper care. All the cleaning, sanitizing, and growing methods covered in this blog still apply. The same seed compatibility also applies to both the stainless steel and silicone versions.

Is the silicone safer than the stainless steel?

Both are food-safe when properly cleaned. The silicone has the practical advantage of no sharp edges, which makes it safer to handle during cleaning and storage. The silicone is also third-party tested and FDA compliant and LFGB Tested & Compliant. The stainless steel is 316-grade food-safe metal.

How do I remove roots after harvest?

Use our Microgreen Medium Scraper to easily remove roots and stems from any reusable grow medium. The process usually takes 30 seconds to 1 minute per tray.

How long does the silicone reusable grow medium last?

Our 1.2mm standard silicone reusable grow medium is rated for 20 to 30+ growing cycles, or roughly 18 to 24 months of regular use at 2 to 4 grows per month. The 1.7mm large-hole version is designed to last for years with proper care.

What's the difference between the 1.2mm and 1.7mm silicone?

The 1.7mm has holes about 0.5mm larger than the standard 1.2mm. The 1.2mm works well for most microgreen varieties (broccoli, radish, kale, mustard, sunflower, and similar). The 1.7mm is designed for larger seeds and aggressive root systems like peas, sunflower, and wheatgrass.

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Final Thoughts

The stainless steel reusable microgreen grow medium was a great product that served our customers well for several years, and we still believe in the value of any high-quality reusable medium over single-use options. After years of side-by-side testing and customer feedback, our current best recommendation is the silicone version, which addresses the main pain points of the stainless steel (sharp edges, weight, rigidity) while keeping all the benefits of a reusable medium.

If you currently own our stainless steel medium, take great care of it and it will last you many more grows. If you're shopping new, head over to our silicone reusable grow medium blog for the full overview of our current flagship product.

We're committed to making sure you have a top-notch experience with On The Grow products. If you have any questions about either medium or need help troubleshooting a grow, our email line is always open.

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Related Blogs You Might Enjoy

• Meet Our Reusable Silicone Grow Medium
• Compatible Microgreen Seeds for Reusable Grow Mediums
• How to Clean and Sanitize Microgreen Trays and Reusable Mediums
• How to Grow Broccoli Microgreens
• How to Grow Microgreens in 10x20 Trays
• How to Start Growing Microgreens: Beginner's Guide
• Case Study: Coco Coir vs Reusable Grow Medium
• How to Grow Pea Microgreens on Various Trays
• Why Are My Microgreens Moldy? Mold vs. Root Hairs
• What Works Best for Harvesting Microgreens
• How to Build a DIY NFT Hydroponic System: Complete Build-to-Harvest Guide

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Updated: May 2026

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