Microgreens are the best entry point into hydroponics if you’re impatient. Seven days from seed to harvest is real, I’m not exaggerating that timeline, and the setup is so forgiving that you can’t actually kill them if you follow a few basic rules. I started with full-size lettuce in a fancy $150 system and felt like I was waiting forever. Then I tried microgreens on a cheap tray with a desk lamp and harvested actual food in a week. It reframed the whole hobby for me.
The speed isn’t the only thing that matters, though. Microgreens have the highest return per square inch of counter space, they’re harder to screw up than seedlings, and they taste better than anything you’ll buy at the grocery store. They’re also the fastest way to prove to yourself that hydroponics actually works. Once you’ve cut your first batch of pea shoots or mustard greens, the $80 investment in a real system feels obvious instead of reckless.
Here’s what you actually need to know to pull this off.
Which Seeds Actually Work
Not every seed grows well as a microgreen. You want seeds that are large enough to handle, germinate fast, and pack a punch flavor-wise. The classics work: broccoli, radish, pea shoots, mustard, sunflower, and arugula. These all hit seven days or close to it. Avoid anything tiny like lettuce seeds for your first batch - they germinate fine but they’re annoying to sow evenly and the harvest isn’t as satisfying.
Buy microgreen-specific seeds if you can find them. Regular vegetable seeds work, but microgreen seeds are usually treated for better germination rates and they’re cheaper per ounce since you use so much less. I grabbed a sampler pack from Johnny’s last fall and it’s lasted me through probably thirty harvests. Seriously, you use maybe a tablespoon of seeds per tray. A single packet goes forever.
Go organic if the price difference isn’t huge. It’s not a religious thing - it’s just peace of mind. You’re eating these in five to seven days, so there’s no time for anything to break down. Whatever’s on the seed is what ends up on your plate.
The Setup: Systems vs. DIY
You have two reasonable paths here. The first is buying a dedicated microgreen system, which takes the guesswork out of everything. The second is using any shallow hydroponic unit and adapting it, which costs less but requires a tiny bit more thinking.
For the system route, the Hopegarden Indoor Garden Hydroponics Growing System: 15 Pods buy on Amazon works fine for microgreens if you remove the individual grow domes and use it as a flat tray instead. The 3L tank is big enough that you don’t need to refill mid-cycle, and the light schedule is already set. You’ll get crowded growth but that’s actually what you want with microgreens. About $40 and it covers you.
The real move, though, is going cheaper. A basic seed tray ($10-15), a clear lid, a small piece of rockwool or coco mat ($5), and a LED shop light from any hardware store ($20-30) gets you there. Humidity is half the battle with microgreens, so a lid that traps moisture beats any fancy system. I’ve had better luck with a $30 flat setup than a $200 tower system, mostly because the design is simpler and there’s less that can go wrong.
If you use an existing countertop hydroponic system, just adapt the growing chamber. Remove the individual pods, lay down rockwool, seed it, and let the circulation system keep the mat damp. The Ahopegarden Indoor Garden Hydroponics Growing System: 10 buy on Amazon or any 10-15 pod unit will work. The circulation does most of the heavy lifting for you.
Germination: The First 48 Hours
Soak your seeds for twelve hours in plain water. This speeds up germination and washes off any dust. A bowl works fine.
After soaking, spread them on your wet growing medium - rockwool cubes, coco mat, or even a folded paper towel if you’re feeling minimal. They should be damp but not sitting in water. Microgreens don’t need nutrients in the water yet. They’re living off seed energy for the first week.
Cover them with a humidity dome, a plate, or anything that traps moisture. No light yet. Just moisture and warmth (65-75°F is fine; your kitchen probably qualifies). The seeds don’t care about light during germination.
Check every twelve hours. The mat should stay wet, not soggy. By hour 36 you’ll see tiny white roots. By hour 48 they should have germinated enough that you can remove the cover and turn the light on.
It’s important not to skip the germination phase. Seeds germinated in the dark, then exposed to light, green up faster and more evenly. You’ll see the difference in density.
The Light Part (And Why It Matters More Than You Think)
Once the seeds have sprouted, light becomes the limiter. You need twelve to sixteen hours of it, and it needs to be close. Within four to six inches of the growing medium is the target. Too far away and you get lanky, pale growth. Too weak and you’re just wasting time.
Any full-spectrum LED will work. Those cheap shop lights from the hardware store are fine. T5 fluorescents are actually ideal for microgreens because they’re cooler and you can put them super close without burning anything. The Hopegarden system I mentioned comes with a built-in light that’s set to sixteen hours, which is perfect.
Blue-spectrum light pushes green, compact growth. Red pushes flowering and stretching. For microgreens, you want mostly blue because you’re harvesting vegetative growth. Some systems have adjustable modes - the Hopegarden has a “vegetables and herbs” setting that defaults to blue. That’s the one you want.
Don’t overthink the light intensity. Microgreens are not demanding. They’re happy with 200-300 micromoles per second if you want to get technical, but honestly, just keep a light closer than your arm is long and you’re fine.
Nutrients and Water
This is the part that stops people. They think they need to mix something complex. You don’t.
Microgreens don’t need nutrient solution at all for the first five days. They’re running on the energy stored in the seed. What they do need is oxygen and moisture. If you’re using a system with circulation, the pump handles oxygen. If you’re using a static tray, mist it once daily or make sure the mat stays damp.
On day five or six, when growth is fully underway, add a diluted nutrient solution. You don’t need much - a quarter-strength dose is plenty. The Hapxalie Hydroponic Nutrients buy on Amazon runs about $15 and comes with a measuring cup. Mix 5ml of A and 5ml of B per liter of water, then use half or a quarter of that concentration. A single bottle lasts forever because microgreen batches use maybe fifty milliliters per tray.
Most beginners either skip nutrients entirely (which is fine, honestly) or burn their greens by adding full-strength solution too early. Underfed microgreens still taste good. Overfed ones taste bitter and the tips can burn.
The Water Question
Use whatever water comes out of your tap. If it’s chlorinated, let it sit for an hour or fill it the night before. That’s it. You don’t need to pH buffer it. You don’t need special filters. Microgreens are tough.
If you’re using a system like the Hopegarden, the 3L tank means you might go the whole week without refilling. If you’re hand-misting, you’ll spray it once a day, maybe twice if it’s dry where you live. There’s no such thing as overwatering microgreens. The worst that happens is mold, which only shows up if it’s genuinely stagnant, not aerated, and already dead.
Harvest: When and How
Seven days is not a hard deadline. It’s the point where most microgreens hit peak flavor and are tall enough to cut cleanly. Pea shoots and sunflower can push to day ten or twelve and get sweeter. Radish and mustard are spicy on day five and mellow out by day nine. Taste-test at day six if you’re impatient.
Harvest with scissors at the base of the stem, just above the soil line. You’re not pulling them up - you’re cutting them. They’re tender and you want a clean harvest. Work from one edge to the other.
Microgreens last about five days in a sealed container in the fridge. They’re best the day you cut them, obviously. Use them on toast, in salads, on scrambled eggs. The flavor is concentrated and weird in the best way.
System Cleanup Between Batches
After you harvest, you need to clean the tray and medium before the next batch. Mold can sneak in if you don’t. Rinse the tray with hot water, dry it completely, and either compost the old medium or toss it. The rockwool or mat is cheap enough that reusing it’s not worth the risk.
If you’re using a circulation system, empty the old water, rinse the tank and pump, and refill. Takes maybe five minutes. I do this while the spent medium is still warm because I’m lazy and it’s easier.
This article is part of our Growing Herbs Hydroponically: Complete Guide — a complete resource for countertop hydroponic growing.
Frequently Asked Questions
Do I really get seven days? From seed to cuttable length, yes. Start counting on the day you sow. Day seven your microgreens are ready. Some crops are faster - mustard can hit harvestable in five days - and some take eight or nine. But the ballpark is real.
Can I grow microgreens without any light? No. They’ll germinate, but they’ll be pale, stretchy, and taste like nothing. Light is not optional. It’s the single biggest factor in whether you end up with something worth eating or just pale sprouts.
What do I do with the roots after harvest? Compost them. They’re wet and getting moldy by the time you harvest. Don’t try to regrow. One batch per medium cycle.
Do I need to pH the water? Nope. Not for microgreens. They’re a one-week crop. By the time pH drift matters, you’re harvesting.
Can I save my microgreens to let them mature into full plants? You can, but they won’t taste as good. Microgreens are bred for that tender, concentrated flavor at one week. Let them keep growing and they get bitter, stringy, and less interesting. Eat them as microgreens or start over with full-size plants in a different system.
The whole point of this is that it works on the first try. You will grow something edible in seven days or less. There’s no learning curve, no expensive equipment required, and you eat better food than you could buy. After your first harvest, you’ll understand why hydroponics gets under people’s skin. It’s not about the technology. It’s about being able to eat something you grew yourself that tastes better than store-bought, in a week, on your kitchen counter.
