How to Grow Microgreens Indoors in an Apartment: A 10-Day Beginner Guide

By The Balcony Harvest Team Published September 30, 2026 9 min read

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Microgreens are the cheat code of small-space gardening: sow on a Sunday, harvest the next weekend. No balcony required, no grow tent, no waiting three months for a tomato. A tray on your kitchen counter, a bag of coco coir, and a packet of radish seeds will give you a faster first harvest than any other crop on this site. Here's the complete 10-day method, including the two mistakes that cause 90% of moldy trays.

What You Need (The Whole List)

The equipment list is short enough to fit in one Amazon order — or one trip to a garden center:

• Two shallow trays (10×20 inch "1020" trays are the standard; one with drainage holes nested in one without). No-hole trays alone work too — just water carefully.
• Growing medium: coco coir is the beginner default — clean, holds moisture evenly, no mess. Hemp fiber mats are the tidier upgrade; seed-starting mix works but is messier indoors.
• Seeds: buy seeds labeled for microgreens or sprouting from a reputable supplier (True Leaf Market and Johnny's are the standard recommendations). Start with radish, broccoli, or kale — fast, forgiving, hard to mess up.
• A spray bottle for gentle watering during germination.
• Light: a bright south-facing windowsill works; a simple full-spectrum LED or a 6500K daylight bulb in a clamp lamp, 12–16 hours a day, works better and costs little.
• Clean scissors for harvest.

Total startup: roughly $25–40 if you buy trays and coir, less if you repurpose takeout containers with holes poked in the bottom. Compare that to the full indoor herb setup — microgreens are the cheapest way to grow food inside, full stop.

The 10-Day Method, Step by Step

Days 1–2: Sow

1. Fill the tray with 1–1.5 inches of pre-moistened coco coir. It should feel like a wrung-out sponge — damp, not dripping. Level the surface with your palm.
2. Sprinkle seeds densely and evenly across the surface — a solid carpet with no big bare patches, but not piled in layers. For small seeds (broccoli, kale, radish), about 1 tablespoon per 10×20 tray; for large seeds (peas, sunflower), 2–3 tablespoons.
3. Press the seeds gently into the medium with a flat board or your palm. Seed-to-medium contact is what drives even germination.
4. Mist the surface lightly, then cover the tray — nest a second tray on top or use a humidity dome. This blackout period keeps moisture in and tells seeds to push roots down first.

Days 3–5: Germinate in the Dark

Keep the tray covered in a warm spot (65–75°F — the top of the fridge works). Check once daily: mist lightly if the surface looks dry. Most varieties sprout in 2–4 days. Large seeds (peas, sunflower) benefit from soaking 8–12 hours before sowing and from a light weight on the cover tray — a book works — to keep them pressed into the medium.

Days 5–6: Move to Light

When most seeds have sprouted and are pushing against the cover, uncover the tray and move it to your light source. If using a grow light, hang it 2–4 inches above the tops of the plants — closer than you'd think. Leggy, pale, floppy microgreens mean one thing: not enough light, or the light is too far away. (Same diagnosis as leggy seedlings — same fix.)

Run the light 12–16 hours a day. A cheap outlet timer ($10) makes this automatic.

Days 6–10: Water From Below

Once uncovered, bottom-water: pour water into the solid outer tray and let the medium wick it up. This keeps the leaves dry (less disease), avoids knocking seedlings flat, and prevents the #2 mold cause — soggy surface conditions.

Daily check: lift a corner of the tray. Light tray = water. Heavy tray = skip. The medium should stay consistently damp, never waterlogged. A small clip-on fan providing gentle airflow for a few hours a day dramatically reduces mold risk — stagnant, humid air is what fungi want.

Day 10 (Give or Take): Harvest

Most microgreens are ready when they're 2–4 inches tall with the first set of true leaves developed (some, like radish, are ready at the cotyledon stage). Harvest by cutting stems just above the medium with clean scissors. Rinse gently, spin or pat dry.

Timing by variety (at room temperature): radish 6–8 days, broccoli and kale 8–12 days, arugula 8–10 days, peas and sunflower 10–14 days. Cold rooms slow everything down; warmth speeds it up.

Storing Your Harvest

Harvest all at once and store in a sealed container or zip bag with a dry paper towel inside — they'll keep a week or more in the fridge. Don't wash until you're ready to eat; wet greens spoil faster. If you can't harvest on schedule, the tray will hold for a few extra days under light with continued watering — microgreens are more forgiving about harvest timing than most crops.

The Easiest Varieties, Ranked for Beginners

1. Radish (any variety) — germinates in 2 days, harvest in a week, spicy kick. The undisputed starter microgreen.
2. Broccoli — mild, fast, high germination rate. Tastes like fresh broccoli stems.
3. Kale — slightly slower than broccoli, same easy care, mild flavor.
4. Arugula — peppery, fast, but a touch more sensitive to overwatering.
5. Mustard — spicy like radish, very fast, dramatic purple varieties available.
6. Peas (shoots) — sweet, crunchy, need soaking and a bit more patience. Worth it.
7. Sunflower — nutty and substantial, but fussier: needs soaking, hulls can stick, slower.

Start with radish or broccoli. Get one successful tray under your belt before experimenting — confidence is the crop that matters most in week one.

Keep a Continuous Harvest Going

The pro move: sow a new tray every week. With 2–3 trays in rotation at different stages, you harvest every few days indefinitely — a permanent salad supply from one windowsill. Used coir goes in the compost or trash (don't reuse it — disease risk), trays get washed with soap and water between rounds, and the whole cycle repeats. Two trays a week is plenty for one or two people.

If microgreens click for you, the natural next steps are windowsill herbs for the same indoor setup — basil and parsley use the same light and trays, just on a longer timeline.