Indoor winter growing
Microgreens Growing Setup: The Trays, Lights and Media That Actually Matter
When the outdoor garden is done for the year, microgreens are the quickest way to keep harvesting something fresh. They grow from seed to harvest in a couple of weeks for many crops, take up a single shelf, and don't care what the weather is doing outside.
The gear list is short, but the details matter: the wrong trays leak, the wrong medium molds, and a sunny windowsill in winter often isn't enough. Here's what to buy, what to skip and how to put it together.
Quick answer
- Core kit: shallow trays (one with holes, one without), a growing medium, a spray bottle, a light, and sharp scissors.
- Soil or coir-based mix is the most forgiving medium for beginners. Hemp or fiber mats are cleaner but dry out faster.
- A simple LED grow light or shop light on a shelf gives much better results than a winter windowsill.
- Buy seed sold for microgreens or sprouting, in bulk if you grow a lot. Garden seed packets are expensive at microgreen sowing rates.
Trays: the 1020 system and why two trays beat one
Most microgreen growers use the standard 10×20-inch flat, usually called a 1020 tray. Shorter half-size and square trays exist too and are handy for small batches.
The common setup uses two trays nested together: a top tray with drainage holes holds the medium and seeds, and a solid bottom tray holds water. You water from below by filling the bottom tray, and the roots draw it up. This keeps the leaves dry, which is the main defense against mold.
Tray with holes
Holds the medium. Drainage holes let you bottom-water.
Solid tray
Catches water and acts as a reservoir. It also serves as a weight or blackout cover during germination.
Humidity dome
Useful for some seeds, but many growers just stack an inverted tray instead.
Thickness matters:Thin, flimsy trays crack after a few uses and leak onto shelves. Heavier-duty trays cost more up front but last for many cycles.
Shop 1020 microgreen traysShop heavy-duty trays
Growing media: soil, coir or mats
| Medium | Pros | Cons | Best for |
|---|---|---|---|
| Seed-starting or potting mix | Forgiving, holds moisture, works for nearly all crops | Messier; soil can stick to harvested greens | Beginners, larger seeds like peas and sunflowers |
| Coconut coir | Clean, light, holds water well, often sold in compressed bricks | Few nutrients; quality varies | Most crops, cleaner indoor growing |
| Hemp or fiber mats | Very clean, easy harvest, little mess | Dry out faster; some crops root poorly | Small seeds like broccoli, radish, mustard |
| Burlap or jute pads | Reusable for some growers, clean | Can be harder to keep evenly moist | Experimenting |
For most people starting out, a fine seed-starting mix or coir in a thin layer is the most forgiving. Once you've got a rhythm, try mats for the crops you grow most and see whether the cleaner harvest is worth the extra watering attention.
Shop coir bricksShop hemp grow mats
Light: windowsill vs grow light
Microgreens need much less light than fruiting plants, but winter windowsills are often too dim and too short-lived. In weak light they grow pale, tall and floppy, leaning toward the window.
A basic LED light on a shelf, hung a short distance above the trays and run on a timer, gives even, upright growth. You don't need a high-powered grow light for microgreens. Many growers use simple LED shop lights or light bars. Our guide to shop lights vs grow lights for seedlings covers the specs, and nearly all of it applies to microgreens too.
- Coverage: the light should cover the whole tray evenly, with no dim ends.
- Adjustable height: chains or hooks let you start it close and raise it if leaves look stressed.
- Timer: a plug-in outlet timer keeps the schedule consistent without you thinking about it.
- Linkable fixtures make it easy to add a second shelf later.
Shop LED light barsShop outlet timers
Seeds: what to grow first
Microgreens use a lot of seed, because you sow thickly. Buying seed labeled for microgreens or sprouting, in larger packs, is much more economical than garden packets. Check that it comes from a supplier that sells it for eating as microgreens or sprouts.
| Crop | Difficulty | Notes |
|---|---|---|
| Radish | Easy | Fast, spicy, colorful varieties available |
| Broccoli, kale, mustard, cabbage | Easy | Mild to peppery; grow well on mats |
| Pea shoots | Easy | Soak seeds first; best in soil or coir; good regrowth for some growers |
| Sunflower | Moderate | Soak, then weight down during germination; hulls need removing |
| Basil, cilantro | Harder | Slower; cilantro germinates unevenly |
| Beet, chard | Moderate | Colorful stems; slower than brassicas |
Start with radish or a brassica mix. They're quick and forgiving, and they'll teach you how your watering and light setup behaves.
The basic growing process
- Fill the holed tray with a thin, level layer of moist medium, or lay a dampened mat in it.
- Sow thickly and evenly. Seeds should cover the surface without piling up. Mist them well.
- Blackout and weight. Put an empty tray on top, upside down, sometimes with a light weight. Darkness and gentle pressure help seeds root down evenly.
- Check and mist daily for the first few days. Lift the cover off once seeds have rooted and pushed up.
- Move under the light and switch to bottom-watering in the solid tray.
- Harvest when the first true leaves are just appearing or at the stage you like, cutting just above the medium.
Small tools that make it easier
- Spray bottle or pump mister for germination.
- Long, sharp scissors or a serrated knife for clean, quick harvesting. Dull blades crush stems.
- A simple wire shelf with room for a light above each level.
- A small fan on low to keep air moving, which helps prevent mold.
- Salad spinner or paper towels for drying harvested greens before storing them.
A basic wire shelving unit is the easiest way to grow more than one tray at a time. Hang a light from the underside of each shelf so the tray below sits a short distance under it, and you can run several batches in different stages at once. Starting one new tray every few days gives you a steady supply instead of a glut followed by nothing.
Mold vs root hairs: telling them apart
Many new growers panic at the white fuzz on radish and brassica roots. That's usually root hairs, which are normal. They look fuzzy and even, cluster around the roots, and tend to disappear when misted.
Mold looks different: cobweb-like strands that spread across the seeds and medium, often with a musty smell, and it doesn't disappear when misted. Prevent it with:
- Sowing evenly, not in clumps
- Bottom-watering instead of watering from above once greens are up
- Gentle airflow from a small fan
- Cleaning trays between batches
If a tray molds, don't eat it. Clean the tray, adjust spacing and airflow, and start again.
The bottom line
Quick verdict
Get a pair of sturdy 1020 trays, a bag of seed-starting mix or a coir brick, a basic LED light on a timer, and bulk radish or brassica seed. That's enough to grow fresh greens all winter on one shelf. Add mats, more shelves and fancier crops once the basics are working.
If you're already setting up lights for spring seedlings, your microgreen shelf can do double duty. See our guide to starting seeds indoors for what comes next.
FAQ
Can I grow microgreens on a windowsill?
You can, but in winter most windowsills give weak, short-lived light, and microgreens grown there often end up pale and leggy. A simple LED light on a timer gives much more even, upright growth.
What's the best growing medium for microgreens?
For beginners, a fine seed-starting mix or coconut coir is the most forgiving. Hemp or fiber mats are cleaner and easier to harvest from but dry out faster and suit small-seeded crops best.
Is the white fuzz on my microgreens mold?
Often it is root hairs, which are normal on radish and brassicas. Root hairs look even and fuzzy around the roots and tend to disappear when misted. Mold spreads like cobwebs over seeds and medium and often smells musty.
Can I use regular garden seed for microgreens?
You can, but microgreens are sown thickly, so small garden packets get expensive quickly. Seed sold specifically for microgreens or sprouting, in larger quantities, is more practical.