How to Grow Microgreens in 10x20 Trays: Soil, Coco Coir & Reusable Mediums
If you've spent any time researching microgreens, you've probably noticed that 10x20 trays are the industry standard, and for good reason. These trays offer the perfect balance of growing space, manageable size, and consistent results. Whether you're growing in a spare room, in a basement grow room, or scaling up for commercial production, understanding how to properly use 10x20 trays is fundamental to your success.
At On The Grow, we've logged over 10,000 hours growing microgreens in every tray size imaginable, but 10x20 trays remain our go-to for most crops. In this comprehensive guide, we'll walk you through everything you need to know about growing microgreens in 10x20 trays using three popular growing mediums: reusable grow mediums (like our 10x20 Reusable Silicone Grow Medium), soil, and coco coir.
This guide is based on information from our free PDF seeding guide available on our website that can be printed out, combined with years of hands-on experience. New to microgreens? Start with our beginner's guide to growing microgreens or grab our Beginner's Guide PDF for a printable walk-through. If you're looking for even more detailed guidance, our Microgreen Masterclass Course specifically covers 10x20, Kratky, and large sprouting trays with in-depth video tutorials.
Quick Answer: How to Grow Microgreens in 10x20 Trays
Growing microgreens in 10x20 trays works the same way across all three popular mediums: place a mesh tray inside a no-holed bottom tray, add your medium (reusable silicone, soil, or coco coir), seed evenly, mist, cover with weight, and germinate in the dark for 2 to 4 days. Once seedlings have lifted the cover, move to light and switch to bottom-watering. Reusable silicone and coco coir both need liquid fertilizer because they have no nutrients on their own, while soil contains its own. Most microgreens are ready to harvest in 7 to 14 days.
Understanding Your 10x20 Trays: Dimensions and Capacity
Before we dive into growing methods, let's clarify what we mean by "10x20 trays" and understand their specifications. Not all 10x20 trays are created equal, and knowing the exact dimensions and capacities of your trays is crucial for consistent results. The 10x20 trays we are referring to in this blog are the ones we sell here on our website.
Standard Shallow 1-inch Deep 10x20 Trays
These are the most common trays you'll encounter. They come in no-holed, mesh, and slotted versions, though we only sell the no-holed and mesh trays. These are what most growers start with. Here are the specs:
Outer Dimensions: 21 inches x 10.75 inches x 1.25 inches
Inner Bottom Dimensions: 19.75 inches x 9.5 inches
Medium Capacity: Hold up to 6 cups of soil or coco coir
Water Capacity (Bottom-Watering): Hold up to 2 cups of water
Reusable Mediums: Compatible with the 10x20 sized reusable grow mediums, or fits 2 10x10 sized reusable grow mediums side by side with a gap.
The shallow depth means you'll need to water more frequently (1 to 2x per day), but they're perfect for most microgreen varieties and are the most space-efficient option for stacking on grow racks.
2-inch Deep 10x20 Trays (No-Holed)
These deeper trays serve multiple purposes and are essential for certain growing setups:
Outer Dimensions: 11.5 inches x 21.4 inches
Inner Dimensions: 9.75 inches x 19.75 inches x 2.25 inches
Medium Capacity: Hold up to 12 cups of soil or coco coir
Water Capacity (Bottom-Watering): Hold up to 14 cups of water (when used in Kratky setup)
Single Tray Use: Only use 2 cups of water if using as a standalone tray
Reusable Mediums: Compatible with the 10x20 sized reusable grow mediums, or fits 2 10x10 sized reusable grow mediums side by side with a gap.
These deeper trays are perfect for Kratky hydroponic setups or crops that benefit from extra root space. One important note: always check your 2-inch deep no-holed trays for any leaks before adding water. While rare, manufacturing defects can happen, and it's better to discover a leak before you've added nutrients and seeded your tray. At this time, we do not sell the 10x20 2-inch deep no-holed trays alone. They are only included in our Kratky Tray Kit.
2-inch Deep Mesh 10x20 Trays
Outer Dimensions: 10.4 inches x 21 inches
Inner Dimensions: 9 inches x 19.5 inches x 2.25 inches
These 2-inch deep mesh trays are designed to sit inside the 2-inch deep no-holed trays, allowing water to reach the roots while keeping the growing medium elevated. Most people use these for growing crops like pea microgreens, or for use in outdoor gardening.
Important Note About "Mesh" and "No-Holed" Terminology
In this blog, when we refer to "mesh trays," we're talking about the Standard Shallow 1-inch Deep 10x20 Trays with mesh holes. The "no-holed tray" is the Standard Shallow 1-inch tray without holes, used as a base for catching water. Together, they make our standard kit that we sell on our website. The 2-inch deep varieties follow the same pattern but with greater depth for hydroponic applications.
The Critical Role of Watering
Before we get into the specific growing methods, let's address the single most important factor in microgreen success: watering. We cannot emphasize this enough. Proper watering is absolutely key to growing healthy microgreens, regardless of which growing medium you choose.
Too much water can lead to root rot, fungal issues, and crops that lay over and fail to develop properly. Too little water results in poor germination, stunted growth, and dried-out plants that never reach their potential. Signs of watering issues include poor germination rates, browning roots, or microgreens laying over instead of standing upright.
The good news? Once you understand the watering needs for your specific setup and environment, it becomes second nature. Different tray depths, growing mediums, and environmental conditions (temperature, humidity, airflow) all affect how much and how often you should water.
Understanding Bottom-Watering Capacities
Bottom-watering is our preferred method for most microgreens because it encourages strong downward root growth, allows the inner canopy of the greens to dry, and reduces the risk of damping off diseases that can occur with top watering. Here's what you need to know about water capacities:
Standard Shallow 1-inch Trays:
- Hold up to 2 cups of water in the bottom tray
- Require more frequent watering due to smaller reservoir
- Perfect for most quick-growing microgreens like broccoli, radish, and kale
Kratky and 2-inch Deep Tray Setups:
- Hold up to 14 cups of water when properly configured
- Water should be refreshed every 2 to 3 days to maintain oxygen levels
- Ideal for longer-growing crops and hands-off growing methods
- Exception: If using a single 2-inch deep tray (not a Kratky setup), only use 2 cups of water
Critical Tip: When bottom-watering, avoid filling water all the way up to the mesh tray. If water floods the medium or sits at the surface, it can suffocate the roots and create perfect conditions for mold and fungal growth. You want the roots to reach down into the water, not the medium to be soaked from above.
Growing with Reusable Grow Mediums in 10x20 Trays
Reusable grow mediums have changed the way many growers approach microgreens. Our 10x20 Reusable Silicone Grow Medium was made to work with 10x20 trays and has become one of our most popular products. Let's walk through the complete process of growing with reusables.
Why Choose Reusable Grow Mediums?
Reusable mediums offer several advantages: long-term cost savings (since you're not constantly buying soil or coco coir), cleaner harvests with minimal root debris, and environmental benefits from reduced waste. They're particularly well-suited for hydroponic nutrients and for those growing indoors.
We've done a lot of testing with over 70 microgreen varieties on reusable mediums. You can read about which seeds work best in our blog post about compatible microgreen seeds for reusable grow mediums.
Step-by-Step: Growing with Reusables in 10x20 Trays
Step 1: Set Up Your Tray
Place your mesh tray on top of the no-holed tray. If you're using a single 2-inch deep no-holed tray with inner ridges that can lift the medium up, you can add the reusable medium directly to that tray instead. If you are using the Kratky tray setup, you place the shallow mesh tray on top of the deep no-holed tray.
Step 2: Prepare the Medium
Evenly place your reusable medium across the mesh tray. It should lay flat and cover the growing surface. Before seeding, lightly mist the medium with water. This serves two purposes. First, it prevents seeds from bouncing when you distribute them. Second, it begins the hydration process that will help with germination. The medium should be damp but not pooling with water.
Step 3: Seed Evenly
Distribute your seeds across the medium, avoiding clumps or dense patches. Unsure how much seed to use? Download our Free Tray-Specific Downloadable PDF Seeding Guide from our website. This guide provides exact seed amounts for dozens of varieties in 10x20 trays. We also recommend ordering quality microgreen seeds from True Leaf Market, our trusted seed source.
After spreading your seeds, mist them with water for about 5 to 10 seconds using a hand pump sprayer. You want the seeds moist and in good contact with the medium, but you should not see water pooling. If pooling occurs, wick it up with a cloth or paper towel immediately, otherwise you might get seed rot in those areas.
Step 4: Cover and Weight
Cover your seeds with a no-holed tray to maintain humidity during germination. This creates a dark, humid environment that encourages uniform sprouting. For shallow tray setups, add a 3 to 7 lb weight on top. The weight helps ensure good seed-to-medium contact and can assist with seed hull removal, particularly important for crops like sunflower microgreens. For more on weight timing, see our guide on transitioning from weight to blackout.
Step 5: Germination Phase
Place the entire tray setup on a dark shelf. For the next several days (typically 2 to 4 days for most crops), you'll mist twice daily, once in the morning and once in the evening. This is where proper watering becomes crucial. Too much water during germination can cause seeds to rot. Too little will result in poor germination rates and drying out.
Step 6: Transition to Blackout
After a few days, check your tray. When you see more yellow plants than dark seeds, meaning germination is well underway, it's time to transition to blackout. Remove the top tray and weight, give the tray a good misting, and check that roots are beginning to reach downward. Then place the tray in blackout by reversing the upper no-holed tray to create a dome above the seedlings.
This blackout dome allows the plants to stretch slightly while still maintaining some humidity. Return the tray to your dark shelf unless your crops are already tall enough (typically when they're pushing strongly against the cover), in which case you can skip this step and move directly to light exposure.
Step 7: Expose to Light and Start Bottom-Watering
After about one day in the blackout dome (or when seedlings are 1 to 2 inches tall), it's time to expose your microgreens to light and begin bottom-watering.
For reusable mediums, we highly suggest you add nutrients. Unlike soil, these mediums contain no nutritional value on their own. Our personal favorite for microgreens is Ocean Solution 2-0-3 mixed at 0.5 oz per gallon of water, with pH balanced to 5.5 to 6.0.
Here's how to water based on your tray setup:
Kratky Setup (using a 2-inch deep tray as reservoir):
Add 14 cups of nutrient-water solution to your reservoir tray. The beauty of the Kratky method is that you typically don't need to refill during the grow cycle. The water level naturally drops as plants consume it, creating an air gap that provides oxygen to roots. Only refill if the water level drops below the bottom of your roots. For more details on this method, check out our comprehensive guide on growing microgreens using the Kratky method.
1-inch Shallow Trays (standard bottom-watering):
Start with 1/4 cup of nutrient-water about twice a day when plants are young and small. As your crops grow and develop larger root systems, gradually increase to 2 cups per watering. You'll notice that mature microgreens can drink a lot of water. Don't be afraid to increase watering as needed, but always check that the previous water has been consumed before adding more. If it hasn't, only add a splash or enough to no longer see the tray uncovered in areas.
Single 2-Inch Deep Trays:
Add 2 cups of nutrient-water beneath the roots twice a day. Pour into an empty corner of the tray, not directly onto the crops. The water should wick up through the medium thanks to the roots without flooding the surface.
Step 8: Harvest
In 7 to 14 days (depending on the variety, since some crops like pea shoots take longer while radish can be ready in 7 days), your microgreens will be ready to harvest. You'll know they're ready when they've developed their first true leaves and have reached 1.5 to 3 inches in height.
After harvest, remove any remaining roots and stems from your reusable medium. Our Microgreen Medium Scraper is purpose-built for this task and makes cleanup fast. You can compost the root debris or feed it to livestock if you have chickens or other animals. Clean and sanitize the medium for reuse. Our 10x20 Reusable Silicone Grow Medium is rated for 20 to 30+ growing cycles with proper care. For detailed cleaning instructions, visit our blog post on how to clean and sanitize microgreen trays and reusable mediums.
If you need more help and visuals for learning how to grow on the reusable silicone grow medium, check out our YouTube playlist below. There are 68+ videos.
Growing with Soil in 10x20 Trays
Soil is the most traditional growing medium and offers several advantages: it contains natural nutrients (reducing or eliminating the need for fertilizers), provides excellent water retention, and creates a familiar growing environment for plants. Many growers prefer soil for its simplicity.
Step-by-Step: Growing with Soil in 10x20 Trays
Step 1: Set Up Your Tray
Place your mesh tray on top of your no-holed tray. This two-tray system allows you to bottom-water effectively while keeping your soil contained.
Fill your mesh tray with a quality potting soil. The amount depends on your tray depth and the type of seeds you're growing:
Standard 1-inch Shallow Trays:
Use about 6 cups of medium for most crops like broccoli, radish, kale, and sunflower.
Special Case for Hard-Shelled Seeds:
For seeds with particularly hard shells like Swiss chard, beets, or some herbs, use a different approach: add 4 cups of soil first, plant your seeds, then cover with the remaining 2 cups. This "soil sandwich" technique helps hold moisture around the seeds and assists with germination and hull removal.
2-inch Deep No-Holed Trays:
Fill with enough medium to leave 1 to 2 inches from the top, or create a 1-inch layer if you prefer. Follow the same seeding rules as above for hard-shelled varieties.
Step 2: Prepare the Medium
Break apart any clumps in your soil and spread it evenly across the tray. Gently press the surface flat without compacting it too much. You want the soil to be level and firm enough to support seeds, but not so compressed that roots struggle to penetrate. A light, fluffy texture is ideal.
Step 3: Add Seeds
Before distributing seeds, lightly mist the soil surface. This prevents seeds from bouncing or rolling into clusters. Then distribute your seeds evenly across the entire surface, avoiding clumps or overly dense areas.
Overcrowding is one of the most common microgreen growing mistakes we see, and it leads to mold issues and weak growth. For detailed seeding guidance specific to each variety, download our seeding guides from our website or enroll in our Microgreen Masterclass Course for video demonstrations.
Step 4: Mist Seeds
Spray your seeds with regular or filtered water for about 13 seconds using a hand pump sprayer. The goal is to hydrate the seeds and help them make good contact with the soil, but you must avoid pooling water or over-saturating the medium. If you see water collecting in areas, blot it up with a paper towel.
Step 5: Cover and Weight
Cover your seeds with a no-holed tray to maintain humidity and create darkness for germination. Optionally (and we highly recommend this for most crops), place a 3 to 7 lb weight on top. The weight provides several benefits: it ensures seeds stay in contact with the soil, encourages strong root development, and can significantly help with seed hull removal.
If you're unsure which crops benefit from weight and which should have just an empty tray, download our Free PDF guides where we detail this information for dozens of varieties.
Step 6: Germination
Store your covered tray on a dark shelf and mist twice daily, once in the morning and once in the evening. During these first few days, your primary job is maintaining proper moisture levels. The soil should stay consistently moist (like a wrung-out sponge) but never soggy or waterlogged.
Step 7: Transition to Blackout
After 2 to 4 days for most crops, check your tray. When seeds have germinated and you see more yellow/white seedlings than dark seeds, it's time to transition. Remove the top tray and weight, give everything a good mist, and check that roots are developing nicely.
Now place the tray in blackout by reversing the no-holed tray to create a dome over the seedlings. This allows them to stretch slightly while protecting them from direct light. Return to your dark shelf unless the crops are already tall enough to skip this step (usually when they're 2+ inches and pushing strongly upward).
Step 8: Expose to Light and Start Bottom-Watering
After approximately one day in the blackout dome, move your tray to your light source and begin bottom-watering. This is where soil shines, because quality potting soil contains nutrients, you typically don't need to add fertilizers, especially for quick-growing crops. Never add fertilizer to soil. Fertilizer is only for coco coir and reusable mediums.
Here's how to water based on your setup:
For Soil in Kratky Tray Setup:
Add 10 to 12 cups of plain water (no nutrients needed with soil). The soil itself provides nutrition.
For 1-inch Shallow Trays:
Start with 1/4 cup twice a day when plants are young. As your microgreens mature and develop larger root systems, gradually increase up to 2 cups per watering as needed. Always allow water to be fully absorbed before adding more.
For 2-inch Deep Trays:
Use a watering can or spray bottle to add water directly to the bottom tray without disturbing the crops growing above. Pour water into a corner and let it distribute naturally beneath the soil.
Step 9: Harvest
In 7 to 14 days, your microgreens will be ready to harvest! The exact timing depends on the variety you're growing and your growing conditions. Microgreens are typically ready when they've developed their first set of true leaves and reached 1.5 to 3 inches in height.
After harvest, remove the remaining roots and stems. You can compost this root mat or feed it to livestock. Chickens particularly love microgreen root mats from what we have heard. For your next grow, always use fresh soil rather than trying to reuse it. For more on what to do with used medium, see our blog on what to do with used grow medium after harvesting.
Growing with Coco Coir in 10x20 Trays
Coco coir offers a middle ground between soil and reusable mediums. Made from ground coconut husks, it's sustainable, has excellent water retention properties, and provides a clean growing environment. It's technically a hydroponic medium (meaning it has no nutritional value), but its texture and handling are similar to soil.
One of the biggest advantages of coco coir is cost-effectiveness. A single brick of compressed coco coir expands to fill approximately four 10x20 trays at 6 cups each.
Step-by-Step: Growing with Coco Coir in 10x20 Trays
The process for growing with coco coir is nearly identical to growing with soil, with one critical difference: coco coir requires nutrients. Let's walk through the process:
Step 1: Set Up Your Tray
Place your mesh tray on top of your no-holed tray and fill it with hydrated coco coir.
Standard 1-inch Shallow Trays:
Use about 6 cups of coco coir for most crops.
Special Case for Hard-Shelled Seeds:
Just like with soil, for seeds with hard shells (Swiss chard, beets, etc.), use 4 cups first, plant the seeds, then cover with 2 cups.
2-inch Deep No-Holed Trays:
Fill leaving 1 to 2 inches from the top, or create a 1-inch layer. Follow the same seeding approach as above.
Step 2: Prepare the Medium
Break apart any clumps in your hydrated coco coir and spread it evenly across the tray. Coco coir should feel moist but not dripping wet. Gently press flat without over-compacting. The texture should be light and fluffy, allowing roots to penetrate easily.
Step 3: Add Seeds
Lightly mist the coco coir surface to prevent seeds from bouncing, then distribute seeds evenly across the entire surface. Avoid clustering or dense patches. Good air circulation between plants is essential for preventing mold and promoting healthy growth.
Step 4: Mist Seeds
Spray seeds with water for about 13 seconds using a hand pump sprayer. You want seeds hydrated and in good contact with the coco coir, but avoid pooling or over-saturation.
Step 5: Cover and Weight
Cover with a no-holed tray to maintain humidity and darkness. Optionally add a 3 to 7 lb weight on top for better seed contact and germination.
Step 6: Germination
Place on a dark shelf and mist twice daily (morning and evening). Coco coir retains water well, so be careful not to overwater. It should stay consistently moist but never waterlogged.
Step 7: Transition to Blackout
When germination is well underway (more seedlings than seeds visible), remove the top tray and weight. Mist, check root development, and place in blackout by reversing the tray to create a dome. Return to dark shelf unless crops are already tall enough to move to light.
Step 8: Expose to Light and Water with Nutrients
This is where coco coir differs significantly from soil. After the blackout phase, expose your microgreens to light and begin bottom-watering with pH-balanced water (5.5 to 6.5 pH range) mixed with hydroponic nutrients. Coco coir itself has no nutritional value, so nutrients are essential for healthy growth. We use Ocean Solution 2-0-3 at 0.5 oz per gallon, pH balanced to 5.5 to 6.0.
For Kratky Tray Setup:
Add 10 to 12 cups of nutrient-water solution.
For 1-inch Shallow Trays:
Start with 1/4 cup twice a day, increasing up to 2 cups as crops mature and develop larger root systems.
For 2-inch Deep Trays:
Use a watering can or sprayer to add nutrient-water to the bottom without disturbing crops above.
Step 9: Harvest
In 7 to 14 days, your microgreens will be ready to harvest. Remove remaining roots and stems. These can be composted or fed to livestock. While coco coir is technically reusable, most growers find it more practical to compost the used coco and root mass and start fresh for the next grow.
Below you will find a playlist from our YouTube channel with over 81 videos showing you how to grow microgreens. Many of these on the playlist are for coco coir.
Pro Tips for Success with 10x20 Trays
After thousands of grows in 10x20 trays, here are some of our top tips that don't always make it into the step-by-step instructions:
Monitor Your Environment: Temperature and humidity significantly impact your watering schedule. In hot, dry conditions, you'll need to water more frequently. In cool, humid environments, less water is needed. Pay attention to how quickly your trays dry out and adjust accordingly.
Learn Your Varieties: Not all microgreens behave the same way. Some (like radish and broccoli) are extremely forgiving and fast-growing. Others (like beets or amaranth) require more attention and specific conditions. Start with easy varieties and expand your repertoire gradually.
Quality Matters: Whether you're using reusable mediums, soil, or coco coir, quality matters. Cheap soil may contain weed seeds or poor drainage properties. Low-quality coco coir might have high salt content.
The "Taste Test" Method: If you're unsure whether your microgreens are ready to harvest, pick a small sample and taste it. This is the best way to determine if the flavor profile is what you're looking for. Some varieties taste better when harvested younger (like mustard, which can become quite spicy), while others benefit from a bit more time to develop.
Watch for Leaks: This is especially important with 2-inch deep trays used for Kratky setups. Always test a new batch of trays for leaks before adding nutrients and seeding. Fill with water, let sit for an hour, and check for any seepage. It's much easier to discover a defect before you've committed seeds and nutrients to the tray.
Documentation is Your Friend: Keep simple notes about your grows: seed amounts, watering frequency, harvest dates, and yields. Even basic record-keeping will help you dial in your system and troubleshoot any issues that arise. Our Microgreen Tray Clip Labelers make it easy to track each tray.
Common Mistakes to Avoid
We've made plenty of mistakes over the years, and we want to help you avoid them. For a deeper dive, check out our full guide on the top microgreen growing mistakes.
Overwatering During Germination: This is the #1 mistake we see. Wet seeds are not happy seeds. During germination, you want consistent moisture, not a swimming pool. If you see water pooling on your reusable medium, soil, or coco coir, you've gone too far.
Inconsistent Watering: Microgreens appreciate consistency. Try to water at approximately the same times each day. Forgetting to water for 24+ hours can stress your crops, while watering three times one day and once the next creates unstable growing conditions.
Overcrowding: More seeds does not equal a better harvest. Overcrowding leads to weak, spindly growth, poor air circulation, and significantly increased risk of mold. Trust the seed amounts in our guides. They're based on hundreds of test grows.
Skipping the Weight: While not all crops need weight, most benefit from it during germination. The weight ensures good seed-to-medium contact and can dramatically improve germination rates and seed hull removal. Don't skip this step unless you have a specific reason.
Harvesting Too Early or Too Late: Harvest timing matters for flavor, texture, and yield. Too early and you're missing potential growth. Too late and some varieties become bitter or fibrous. The sweet spot is usually when the first true leaves have just emerged.
Ignoring pH (for Hydroponic Setups): If you're using reusable mediums or coco coir with hydroponic nutrients, pH matters. Most microgreens prefer a pH range of 5.5 to 6.5. Water outside this range can lock out certain nutrients even if they're present in your solution.
Troubleshooting Common Issues
Poor Germination:
Check your watering (most common cause), seed quality and age, temperature (most seeds prefer 65 to 75°F), and whether you're maintaining humidity with your cover tray.
Mold or Fungus:
This usually indicates too much moisture, poor air circulation, or overcrowding. Reduce watering frequency, ensure good airflow, and check your seeding density. See our complete mold prevention guide for more.
Browning Roots:
Often a sign of overwatering or poor drainage. With reusable mediums or Kratky setups, brown roots might indicate the water level is too high and suffocating roots.
Crops Falling Over:
This can happen from insufficient light (causing weak, leggy growth), overwatering, or removing the cover too early in the germination process. Our complete microgreen lighting guide covers proper light setup in detail.
Uneven Growth:
Usually caused by uneven seeding, inconsistent watering, or uneven light coverage. Make sure your light source covers the entire tray uniformly.
Frequently Asked Questions
How many cups of soil or coco coir do I need for a 10x20 tray?
For a standard 1-inch shallow 10x20 tray, use about 6 cups of soil or coco coir for most crops. For seeds with hard shells like Swiss chard or beets, use 4 cups first, plant the seeds, then cover with 2 more cups. For a 2-inch deep tray, you can fill with up to 12 cups, or use a 1-inch layer depending on your preference.
How much water goes in the bottom of a 10x20 tray?
Standard 1-inch shallow trays hold up to 2 cups of water in the bottom. 2-inch deep trays used in a Kratky setup hold up to 14 cups. A single 2-inch deep tray (not Kratky) should only use 2 cups. Always avoid filling water up to the mesh tray itself, since that can suffocate roots.
Do I need to add fertilizer when growing in 10x20 trays?
It depends on your medium. Soil contains its own nutrients, so no fertilizer is needed. Reusable silicone and coco coir are both inert, meaning they contain no nutrients, so fertilizer is required for healthy growth. We use Ocean Solution 2-0-3 at 0.5 oz per gallon, pH balanced to 5.5 to 6.0. Never add fertilizer to soil.
How long do microgreens take to grow in a 10x20 tray?
Most microgreens are ready to harvest in 7 to 14 days from seed. Fast varieties like radish and broccoli can be ready in 7 to 10 days. Slower varieties like pea shoots, sunflower, and beets typically take 10 to 14 days. Harvest when the first true leaves emerge and the plants reach 1.5 to 3 inches in height.
Can I reuse the silicone grow medium for multiple grows?
Yes. Our reusable silicone 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. After each harvest, remove root debris with our Microgreen Medium Scraper, rinse, and sanitize between cycles. See our cleaning and sanitizing guide for the full process.
What's the best growing medium for beginners?
Soil is generally the most forgiving for first-time growers because it holds moisture well and contains its own nutrients, so you don't have to mix fertilizer. Once you're comfortable, the reusable silicone grow medium offers cleaner harvests and long-term cost savings, and coco coir is a good middle-ground option. New growers should start with our beginner's guide to growing microgreens.
Next Steps and Additional Resources
Growing microgreens in 10x20 trays is a skill that improves with practice. Every grow teaches you something new about how your environment, your watering technique, and your seed varieties interact.
If you're hungry for more information, we have extensive resources available:
Free Downloads:
- Free Tray-Specific Downloadable PDF Seeding Guide. Exact seed amounts for dozens of varieties in 10x20 trays.
- Free Microgreen Troubleshooting, FAQ & Lingo PDF. Comprehensive guide to common issues and microgreen terminology.
Video Content:
Visit our on-site Video Library for hundreds of videos showing the complete growing process for different varieties, tray types, and growing methods.
Comprehensive Course:
Our Microgreen Masterclass Course specifically covers 10x20, Kratky, and large sprouting trays with detailed video walkthroughs for soil, coco coir, and reusable growing mediums.
Product Recommendations:
All the trays, growing mediums, and supplies mentioned in this guide are available on our website:
Connect With Us:
Follow us on Facebook to see what we're growing, ask questions, and connect with our growing community of microgreen enthusiasts.
Final Thoughts
The beauty of 10x20 trays is their versatility. Whether you're growing with reusable mediums for a clean hydroponic setup, using soil for its simplicity and natural nutrition, or choosing coco coir for its cost-effectiveness and sustainability, these trays provide a reliable, standardized platform for success.
Remember that growing microgreens is as much art as science. While we've provided detailed instructions based on our experience with thousands of grows, your environment, water quality, seed sources, and even your local climate will create unique growing conditions. Don't be afraid to experiment within these guidelines and adjust techniques to match what works in your space.
Start with easy varieties like broccoli or radish, master the basics of watering and light exposure, and then expand to more challenging crops. Each tray you grow will teach you something new, and before long, you'll develop an intuition for what your microgreens need.
Most importantly, have fun with it. There's something deeply satisfying about harvesting fresh, vibrant microgreens you've grown yourself, whether they're destined for your morning smoothie, a restaurant dish, or a farmer's market sale.
Happy growing!
Related Blogs You Might Enjoy
- Microgreens vs. Mature Vegetables: Grow Time and Water Usage Compared
- Inside The Microgreen Masterclass: What's Actually Inside The Course
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- How to Grow Radish Microgreens: The Fastest Beginner Crop
- How to Start Growing Microgreens: Beginner's Guide
- Meet Our Reusable Silicone Grow Medium
- Compatible Microgreen Seeds for Reusable Grow Mediums
- How to Clean and Sanitize Microgreen Trays and Reusable Mediums
- Why Are My Microgreens Moldy? Mold vs. Root Hairs
- Complete Microgreen Lighting Guide
- Weight to Blackout Timing Guide
- Growing Microgreens Using the Kratky Method
- Top Microgreen Growing Mistakes and How to Avoid Them
Published: January 2026
Updated: May 2026
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