Many beginners make the same tray mistake: they grab whatever container is available, fill it with growing media, sow their seeds, and wonder a week later why half the crop is sitting in a puddle while the other half dried out unevenly. Choosing the wrong microgreens growing trays is one of the most common setup errors we see at Habitat Hydroponics, and it is almost always the tray driving the problem, not the seeds or the nutrients.
The good news is that choosing the right tray is simple once you understand the four decisions that actually matter: size, depth, drainage design, and material. Each one affects yield, hygiene, and daily labour in concrete ways. Get these right from the start and you will spend less time troubleshooting and more time harvesting. And it is worth getting right: microgreens are one of the fastest ways for anyone in Namibia, with or without land, to start growing food at home.
By the end of this guide, you will be able to choose the right tray combination for your setup with confidence, whether that is a two-shelf windowsill operation growing herbs for your kitchen or a small production run selling at a local market.
Microgreens Growing Trays: Size Breakdown for 1020, 1010, and 5x5
The 10x20 (1020) Standard and Who Actually Needs It
The 1020 tray, measuring roughly 25 × 50 cm on the outside, is the industry benchmark for a practical reason: it maximises growing area per shelf on a standard grow rack. A single 4-tier rack can hold 8 to 10 of these trays per shelf, roughly 32 to 40 trays in one footprint, depending on rack width and manufacturer specs. That maths makes the 1020 the clear choice for anyone producing at commercial scale or harvesting regularly for sales.
One thing most beginners miss: the inner dimensions determine your yield, not the outer measurements printed on the product listing. The standard inner growing area of a 1020 tray is about 1,290 cm², and that is the number to use when calculating how much seed you need and what your expected harvest weight will be.
When 10x10 and 5x5 Trays Are the Smarter Choice
Home growers with limited rack space often get more value from smaller seedling trays. A 1010 half-tray gives you the same depth and drainage options as a full 1020 at half the footprint, so you can run two different crop varieties in the same shelf slot. The 5x5 tray is one-eighth the size of a 1020 and works particularly well when you want to trial a new variety before committing a full tray to it. Sunflower shoots behaving differently than expected? Test them in a 5x5 first.
Both the 1010 and the 5x5 are designed to nest inside a standard 1020 reservoir tray, so you are not sacrificing the bottom-watering system when you downsize. Two 1010 trays or several 5x5 trays fit inside a single full-size reservoir tray without modification, though it is worth confirming dimensions with your specific supplier, since outside measurements vary slightly between manufacturers.
Mixing Sizes on a Single Grow Rack
Most experienced home growers end up running a mix of tray sizes on the same rack, and this is a feature, not a workaround. A 1020 of radish, a 1010 of basil, and two 5x5s of specialty microgreens on a single shelf gives you variety without overcommitting space to crops you have not sold yet. Treat size flexibility as part of your production strategy from the beginning.
Depth Guide for Microgreens Growing Trays: Shallow vs. Deep
Why Shallow Trays (2.5 to 4 cm) Cover Most Microgreens
The overwhelming majority of microgreens, including radish, broccoli, kale, mustard, and amaranth, have minimal root mass and only grow 5 to 7 centimetres tall. Shallow trays at 2.5 to 4 cm (1 to 1.5 inches) deep are a strong match: they use less growing media, allow better air circulation around cut stumps after harvest, and make cutting easier because the canopy sits right at tray level rather than deep inside a half-filled container. If you are only going to stock one tray depth, shallow is the right call for nearly every variety you will grow.
The trade-off is water-holding capacity. Shallow trays dry out faster and typically need watering once or twice daily. Twice daily becomes necessary in warm environments above roughly 24 °C with low humidity, which describes Windhoek's warm, dry air for much of the year, so build a consistent watering schedule into your routine from day one and it will not catch you off guard.
The Crops That Need Deeper Trays
Pea shoots, sunflowers, and wheatgrass develop larger root systems and taller stems that often benefit from around 4 to 5 cm (1.5 to 2 inches) of depth. The extra depth gives structural support as the plants grow taller and gives the root mass enough room to anchor properly. Exact needs vary by variety and growing medium, so treat these figures as a starting point rather than a hard rule. Using a deep tray for short-variety microgreens is actually counterproductive: the underfilled space creates poor air circulation around the stem base, which increases mould risk and wastes growing media you paid for.
How Depth Affects Your Daily Watering Routine
Shallow trays need consistent daily attention because their lower water-holding capacity means the growing medium dries out faster. Deep trays offer more buffer, which is useful for taller crops that spend more time in the tray before harvest. Think of tray depth as directly tied to your watering schedule: if you cannot check your setup twice a day, lean toward deeper trays for any crop that tolerates them.
Drainage Options for Microgreens Growing Trays: The Bottom-Watering System Explained
How the Double-Flat System Works
The standard setup for microgreens is a perforated inner tray sitting inside a solid outer reservoir tray, often sold as a bottom-watering pair. You pour water into the outer tray, and the growing medium wicks moisture upward through the drainage holes by capillary action. Bottom watering reduces wet foliage and typically lowers damping-off and mould risk compared with top watering, for one clear reason: it keeps the canopy completely dry. Dry foliage means reduced disease risk, no soil splashing onto the greens before harvest, and roots that grow downward toward the water source rather than staying shallow near a wet surface.
Fungi like Pythium, the organism responsible for damping-off, need wet foliage and high surface humidity to establish. Bottom watering eliminates both conditions. Top watering recreates them with every irrigation cycle.
Why a Tray Without Drainage Holes Is Non-Negotiable
Using a single solid tray as your only growing container is a structural failure point, not a preference. Without drainage holes, excess water has nowhere to go. The growing medium becomes saturated, oxygen is cut off from the root zone, and waterlogging can quickly lead to mould and crop loss. This scenario is behind most of the "I lost my whole crop" stories we hear from new growers. A drainage hole is not a design feature you can skip to save money on a second tray.
One caveat: bottom watering is not the right method during the initial germination phase, before roots have established. During the blackout period, seeds absorb moisture from the surface, so the medium should be pre-moistened at sowing. Switch to bottom watering once germination is complete and root tips are visible through the bottom of the tray.
When a Solid Tray Works on Its Own
There is exactly one scenario where a solid tray without holes serves a useful purpose: as the reservoir tray in a double-flat system, and that is the only place it belongs. It is not the growing tray. Keep that distinction clear when you are buying, and you will not end up with a stack of solid trays you cannot actually grow in.
What Tray Material Actually Means for Food Safety and Durability
Polypropylene (PP #5): Why It's the Default for Good Reason
Food-grade polypropylene is the most practical material for microgreens growing trays and the most widely used in both commercial and home setups. It is BPA-free, non-toxic, capable of supporting substantial loads of wet growing media without warping, and dishwasher safe on a normal cycle. Many quality PP trays come with multi-year warranties, so check the manufacturer specs for the specific model you are buying, since warranty terms vary by brand.
There are two things to watch for. First, always confirm a tray is explicitly labelled "food grade". Not all plastic trays are, and non-food-grade plastics can leach compounds into your growing medium over time. Second, skip the sanitise cycle on the dishwasher and never use boiling water. The high heat warps the tray, and a warped tray does not sit flat in your reservoir, which breaks the bottom-watering system.
Biodegradable and Compostable Tray Alternatives
Cornstarch-based and sugarcane compostable trays are a legitimate option for growers who prioritise environmental impact. They perform well through a single grow cycle and decompose in roughly 90 days in a compost pile, which is useful if you run a soil-to-compost closed loop at home. The limitation is durability: these trays are single-use by design, which makes them suitable for eco-focused home setups but impractical for commercial operations that need long-term reliability. Microgreen tray kits built around compostable options exist for growers specifically looking to minimise plastic use from the start.
Stainless Steel Trays for Long-Term Investment
316-grade stainless steel sits at the premium end of the materials spectrum: certified food-grade, resistant to corrosion, and built to handle boiling water and bleach without degrading. That makes stainless the right call for high-sanitation commercial operations with strict food safety requirements. For most home growers and small-scale producers, the cost premium over food-grade PP is not justified at the start. Begin with polypropylene, and upgrade to stainless once your scale demands it.
Reusable vs. Single-Use Trays: The Real Cost Comparison
Cost per Grow Cycle Over Time
The comparison is simple. A quality polypropylene 1020 tray lasts through dozens of grows, so once you spread the purchase price across every cycle, the cost per grow becomes trivially small. A compostable tray, by contrast, costs you its full price every single cycle. If you are running multiple trays per week, reusable PP trays typically pay for themselves within the first month or two of regular use. Prices change, so check the current listings on the Habitat Hydroponics store for what trays cost today.
How to Clean and Sanitise Reusable Trays Properly
After harvest, rinse root matter off the tray immediately, before it dries and bonds to the plastic. Wash with hot soapy water, then sanitise with standard 3% hydrogen peroxide applied undiluted to all tray surfaces. Let the solution sit for 10 to 20 minutes. Hydrogen peroxide breaks down naturally into water and oxygen, so no rinsing is required, though always verify this against current food safety guidelines for your specific operation. Then let the tray air dry completely before the next use.
Skipping the drying step is one of the leading causes of cross-contamination between grows. Residual moisture in a stacked tray creates exactly the humid, enclosed environment where mould spores establish. Drying takes no effort and prevents a lot of problems. Trays are dishwasher safe on normal cycles only, which can stand in for the soap-and-water step if you are running a high volume of trays.
Completing Your Setup with the Right Growing Media
What Goes in the Tray Matters as Much as the Tray Itself
Even the best tray produces mediocre results with the wrong growing medium. The two most common options for microgreens are vermiculite for soil-based setups and rockwool for hydroponic-style growing, and they serve different growers in different ways. Choosing the right medium for your crops and your watering system is the final piece of the setup puzzle.
Vermiculite and Rockwool: When to Use Each
Vermiculite is the go-to for most soil-based microgreens setups. It is lightweight, pH-neutral, and excellent at retaining moisture while staying aerated enough to prevent waterlogging. A thin layer of vermiculite on top of a seed-starting mix also helps maintain consistent surface moisture during germination without creating the wet-canopy conditions that lead to mould. For growers running a more controlled, hydroponic-style microgreens system, Grodan rockwool plugs provide a clean, soil-free substrate with precise water retention and excellent structural support for root development. Both pair well with standard 1020 or 1010 microgreens growing trays and the double-flat drainage system.
Where to Source Everything in One Place
Piecing together orders from multiple suppliers adds time, shipping costs, and the risk of mismatched components. At Habitat Hydroponics, we stock microgreens growing trays alongside vermiculite, Grodan rockwool plugs, propagation trays, and the rest of what you need to get a complete growing station running in one order, all held locally in Windhoek with fast delivery across Namibia. If you are not sure which combination suits your setup, reach out directly and we will help you work through it based on your space, crop selection, and budget.
Putting the Decision Together
The right tray is not one product; it is a combination. The correct size for your production scale, the appropriate depth for your crop selection, a double-flat drainage setup with a perforated inner tray and solid outer reservoir, and a food-safe material that fits your budget and sustainability preferences. These four decisions, made in the right order, determine whether your microgreens setup runs smoothly from the first grow or becomes an ongoing troubleshooting exercise.
For most growers starting out, standard 1020 shallow microgreens growing trays in food-grade polypropylene paired with vermiculite or Grodan rockwool will cover your needs from day one. Add a couple of 1010 trays for variety, set up the double-flat drainage system, and you have a foundation that scales as your production grows.
Head to Habitat Hydroponics to order everything your microgreens setup needs in one place: growing trays, reservoir trays, vermiculite, Grodan rockwool plugs, and any additional propagation supplies to get your first grow started. No juggling multiple suppliers, no guessing on compatibility.
Frequently asked questions
What size microgreens tray should I start with? A standard 1020 double-flat pair (roughly 25 × 50 cm) covers most home setups. Add 1010 or 5x5 trays when you want to run more varieties on the same shelf without committing a full tray to each.
Do microgreens trays need drainage holes? The growing tray does; the reservoir tray must not have any. Grow in a perforated tray nested inside a solid one, and bottom-water once roots are visible at the base.
How deep should a microgreens tray be? 2.5 to 4 cm suits nearly every variety. Pea shoots, sunflower and wheatgrass do better with around 4 to 5 cm of depth for their larger root systems.
How do I clean trays between grows? Rinse straight after harvest, wash with hot soapy water, sanitise with 3% hydrogen peroxide for 10 to 20 minutes, and let the trays dry completely before stacking them again.
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