Grow Microgreens on a Windowsill: Fresh Greens in 10 Days

If you want the joy of gardening without the long commitment, microgreens are the move.

They grow fast (10 to 14 days from seed to harvest), they taste great (peppery radish, earthy broccoli, spicy mustard), and they make even a random Tuesday dinner look like you tried. A handful of fresh microgreens on top of scrambled eggs or a salad looks fancy but takes zero effort. They are also perfect for busy parents because the timeline is short. You can mess up, learn, and try again next week. No six-month commitment like tomatoes. No waiting months for herbs to grow big enough to harvest.

Microgreens are probably the fastest win in home gardening. I started growing them on my kitchen windowsill when I had a toddler and zero time, and I still keep a rotation going because the payoff is so fast.

What Are Microgreens?

Microgreens are young seedlings harvested when they have their first set of true leaves (usually 1 to 3 inches tall). You harvest them when they are about 7 to 14 days old, depending on the variety.

They are not sprouts (which are grown in water, eaten root and all, and harvested in 3 to 5 days). Microgreens grow in soil or a growing medium, need light, and you cut the stems above the soil line. You eat the stems and leaves but not the roots.

They are also not baby greens (which are harvested later, at 3 to 4 weeks old, and are larger). Microgreens are harvested earlier, when the flavor is most concentrated.

Why grow microgreens instead of sprouts or baby greens?

Faster than baby greens (10 days vs 3 to 4 weeks)
More nutritious than mature greens (higher concentration of vitamins and antioxidants)
Less risk of bacteria than sprouts (grown in soil with light, not just water)
More flavor than baby greens (intense, concentrated taste)

What You Need (Keep It Simple)

Essential supplies:

A shallow tray (or any food container with drainage holes poked in the bottom)
- Size: 10 x 20 inch standard nursery tray works great, or any shallow container 1 to 2 inches deep
- Plastic takeout containers work fine if you poke holes in the bottom
A second tray to catch water (no holes)
- This sits under the first tray to catch drainage
Potting mix or seed-starting mix (not garden soil)
- Seed-starting mix is lighter and easier for seeds to push through
- Potting mix works but is heavier
- About 1 to 1.5 inches of soil per tray
Microgreen seeds (radish is the easiest)
- Buy seeds labeled “for microgreens” or organic sprouting seeds (untreated)
- Do not use seeds treated with fungicides (labeled “treated” or “coated”)
A sunny windowsill (south or west-facing is best) or a small grow light
- Needs at least 4 to 6 hours of bright light per day
- A basic LED grow light works if you do not have a sunny window
Scissors (for harvesting)

Optional but helpful:

A spray bottle (for gentle watering)
A small fan (for airflow to prevent mold)
A second tray for covering during the blackout phase (or use a lid, cardboard, or towel)

Where to buy seeds:

Online: True Leaf Market, Johnny’s Seeds, or any seed supplier with a microgreens section
Local: Some grocery stores sell sprouting seeds (check the bulk section)
Cost: $5 to $10 for enough seeds for 10 to 20 trays (seeds are cheap)

Best Microgreens for Beginners

Start with one of these:

Radish (the easiest, my #1 recommendation):

Flavor: Peppery, crunchy, slightly spicy
Speed: 7 to 10 days
Why it is beginner-friendly: Germinates fast, grows thick and tall, forgiving of mistakes
Best use: Salads, sandwiches, tacos

Broccoli:

Flavor: Mild, slightly earthy, tastes like broccoli
Speed: 10 to 12 days
Why it is beginner-friendly: Germinates reliably, grows evenly
Best use: Smoothies, salads, wraps

Kale:

Flavor: Earthy, slightly sweet, mild compared to mature kale
Speed: 10 to 12 days
Why it is beginner-friendly: Hardy, grows well in cool conditions
Best use: Salads, smoothies, garnish

Mustard:

Flavor: Spicy, pungent, bold
Speed: 7 to 10 days
Why it is beginner-friendly: Fast and forgiving
Best use: Asian dishes, sandwiches, spicy mixes

Arugula:

Flavor: Peppery, nutty, slightly bitter
Speed: 10 to 12 days
Why it is beginner-friendly: Reliable germination
Best use: Salads, pizza topping, pasta

Skip these at first:

Cilantro (slow, takes 2 to 3 weeks, hull stays on seeds and is annoying)
Basil (slow, takes 2 to 3 weeks, needs warm conditions)
Sunflower (requires pre-soaking, more steps, shell removal)
Peas (needs soaking, takes longer)

Once you have the hang of radish or broccoli, you can try the slower or more finicky varieties.

Step-by-Step: The 10-Day Plan

Day 0: Prep the tray (5 minutes)

Add 1 to 1.5 inches of moist (not soaking wet) soil to your tray
- Moist means: If you squeeze the soil, a few drops of water come out
- Too wet: Water pools on the surface
- Too dry: Dusty, does not clump
Level the soil gently (use your hand or the bottom of a cup)
- No need to pack it hard, just smooth
Sprinkle seeds evenly across the surface
- Aim for dense coverage but not piled on top of each other
- For radish: About 1 to 2 tablespoons per 5 x 5 inch tray
- Seeds should almost touch but not overlap
Press seeds lightly into the soil (use your hand or the bottom of a flat object)
- This ensures good contact with the soil
Mist the top with a spray bottle so everything is settled and moist

What it should look like:

Seeds evenly distributed, lightly pressed into the soil, with most of the soil surface covered

Day 0 to Day 3: The blackout phase (3 days)

This part makes stems grow stronger and prevents leggy, weak seedlings.

What to do:

Cover the tray with another tray flipped upside down, a lid, cardboard, or a towel (anything that blocks light)
Keep it in a warm spot (65 to 75 F is ideal)
- Warmer = faster germination
- Cooler = slower germination
Mist the soil once or twice a day so it stays damp (not soaking wet)
- You can lift the cover to mist, then replace it

What is happening:

Seeds are germinating in the dark
Stems are pushing up toward the light (even though there is no light yet)
This is called “stacking” and it makes the stems stronger

What you should see by Day 3:

Little sprouts pushing up (usually 1 to 2 inches tall)
Seeds cracking open and roots reaching into the soil
Stems are pale yellow or white (this is normal, they will turn green in the light)

If you do not see sprouts by Day 3, check:

Was the soil too dry? (mist more frequently)
Was it too cold? (move to a warmer spot)
Were the seeds old or bad? (try fresh seeds)

Day 3 to Day 10: Light and growth (7 days)

What to do:

Remove the cover and move the tray to bright light (a sunny windowsill or under a grow light)
- Needs at least 4 to 6 hours of bright light per day
- More light = greener, healthier microgreens
Water from the bottom if you can (pour water into the drainage tray, let the soil soak it up from below)
- This reduces mold risk because the surface stays drier
- If you can not bottom water, mist gently from the top
Keep the soil evenly moist, not soaking wet
- Check daily and water when the soil starts to feel dry on top

What is happening:

Stems turn green as chlorophyll develops
True leaves start to form (the first leaves after the seed leaves)
Roots grow deeper into the soil

What you should see by Day 10:

Microgreens are 2 to 4 inches tall
Leaves are full and green
Stems are thick and sturdy (not thin and leggy)

Day 10: Harvest (2 minutes)

When to harvest:

Leaves look full and green
Stems are 2 to 4 inches tall
True leaves have formed (the first leaves after the seed leaves)

How to harvest:

Use scissors and cut the stems just above the soil line
Rinse gently under cool water
Pat dry with a towel or use a salad spinner
Use immediately or store in the fridge in a sealed container (lasts 3 to 5 days)

Can you regrow after cutting? No. Microgreens do not regrow after you cut them. Once you harvest, compost the soil and roots and start a new tray.

How much will you get? A 5 x 5 inch tray yields about 1 to 2 cups of microgreens (enough for 2 to 4 servings).

How to Water Without Making a Mold Farm

Mold is the most common microgreens problem. It grows when the soil is too wet, the airflow is poor, or the seeds are too crowded.

Best practices to prevent mold:

Bottom water when possible (after Day 3, once the roots are established):
- Pour water into the drainage tray (the tray under the growing tray)
- Let the soil soak up water from below for 10 to 15 minutes
- Dump out any excess water that the soil did not absorb
- This keeps the surface drier and reduces mold risk
Keep airflow moving (especially if your home is humid):
- A small fan blowing gently near the trays helps
- Or crack a window for fresh air
- Stagnant, humid air is mold’s best friend
Do not keep the soil drenched:
- Moist is good. Soaking wet is bad.
- If water pools on the surface, you used too much
- Let the soil dry slightly between waterings (but not bone dry)
Use a clean tray:
- Wash trays with soap and water between uses
- Dirty trays can carry mold spores from previous batches
Do not overcrowd seeds:
- Seeds should almost touch but not pile on top of each other
- Too many seeds = poor airflow = mold

How to tell if it is mold or root hairs:

In the first few days, you might see white, fuzzy growth. This could be:

Root hairs (normal): Fine, wispy white hairs growing straight down from the roots. They look like tiny threads and disappear when you mist them.
Mold (problem): Webby, cottony white or gray growth that spreads across the surface. It smells musty and does not go away when you mist it.

If you see mold:

Increase airflow (add a fan)
Bottom water only (stop misting the surface)
Reduce watering frequency
If the mold is widespread, compost the tray and start over

Common Mistakes

Using too much seed (crowding causes mold)

Problem: Seeds piled on top of each other, stems grow thin and weak, mold spreads quickly.

Fix: Use less seed. Seeds should almost touch but not overlap. If you are not sure, start with less and add more next time if needed.

Keeping the tray too wet

Problem: Soil is soaking wet, water pools on the surface, mold grows, seeds rot.

Fix: Water less frequently. Let the soil dry slightly between waterings. Bottom water instead of misting the surface. Use well-draining soil.

Not enough light (leggy growth)

Problem: Stems grow tall and thin, leaves stay small and pale, stems flop over.

Fix: Move the tray closer to a window or add a grow light. Microgreens need at least 4 to 6 hours of bright light per day after Day 3.

Forgetting airflow

Problem: Mold grows, stems stay wet, soil smells musty.

Fix: Add a small fan or crack a window. Stagnant air is mold’s best friend. Moving air dries the surface and prevents mold.

Skipping the blackout phase

Problem: Stems grow weak and leggy, microgreens flop over.

Fix: Cover the tray for the first 3 days. The blackout phase (called “stacking”) forces the stems to grow strong and thick before they hit the light.

Using old or treated seeds

Problem: Seeds do not germinate, or germination is patchy and slow.

Fix: Use fresh seeds (check the date) and make sure they are untreated (no fungicide coating). Buy seeds labeled “for microgreens” or “for sprouting.”

Forgetting to harvest on time

Problem: Microgreens grow too tall, leaves get bitter, stems get tough.

Fix: Harvest when the first true leaves form (usually 7 to 14 days, depending on the variety). Do not wait too long or the flavor and texture decline.

What To Do Next

If your first tray was a success:

Start a weekly rotation so you always have a tray growing (stagger start dates by 3 to 4 days)
- Tray 1: Harvest Day 10
- Tray 2: Harvest Day 13 (started 3 days later)
- Tray 3: Harvest Day 16 (started 3 days after Tray 2)
- This gives you a constant supply without overwhelming your fridge
Try a spicy mix (radish plus mustard for a bold flavor)
Or try a mild mix (broccoli plus kale for smoothies and salads)

If your first tray failed:

Check the most common causes: too much water, not enough light, old seeds, or poor airflow
Try again with fresh seeds and better drainage
Start with radish (the most forgiving variety)

If you want to scale up:

Try multiple trays at once (start 2 to 3 trays on the same day)
Experiment with different varieties (sunflower, peas, arugula)
Try a larger tray (10 x 20 inch standard nursery tray yields a lot more)

If you want a bigger project:

Graduate to herbs like Thai basil, cilantro, or green onions (longer timeline, but more satisfying)
Try sprouting (faster than microgreens, no soil needed, eaten root and all)
Or try baby greens (let the microgreens grow for another 2 to 3 weeks for larger leaves)

How to use microgreens:

Salads (toss with lettuce, cherry tomatoes, and vinaigrette)
Sandwiches (layer on top of turkey, avocado, or hummus)
Tacos (garnish with radish or mustard microgreens for a spicy kick)
Smoothies (add broccoli or kale microgreens for extra nutrition)
Eggs (sprinkle on scrambled eggs, omelets, or avocado toast)
Soups (garnish ramen, pho, or tomato soup)
Pizza (add arugula microgreens after baking)

Microgreens are one of the fastest, most rewarding home gardening projects. If you can keep a tray going for 10 days, you can keep a rotation going indefinitely. And once you taste the difference between store-bought greens and fresh-cut microgreens, you will never want to go back.