Microgreens are one of the quickest edible crops you can grow indoors. With a shallow container, a small amount of growing medium, and a bright windowsill, you can harvest tender greens in roughly one to three weeks.
Choose the Right Windowsill
Before sowing, inspect the space where your microgreens will grow. A successful windowsill setup needs light, a reasonably steady temperature, and protection from drafts.
A south-facing window usually provides the strongest natural light in the Northern Hemisphere. East- and west-facing windows can also work well, while a north-facing window may be too dim, especially in winter. Bright indirect light can produce acceptable greens, but insufficient light often causes thin, pale, leaning stems.
Keep the tray away from radiators, heating vents, air conditioners, and frequently opened exterior doors. Excess heat dries the growing medium quickly, while cold drafts can slow germination. A comfortable indoor temperature of about 60–75°F (16–24°C) works for most common microgreen varieties.
If your window receives less than several hours of bright light, supplement it with a small LED grow light. Position the light according to the manufacturer’s instructions, usually a few inches above the seedlings, and provide a regular day-and-night cycle. A timer makes this easier and prevents you from leaving the light on continuously.
Protect the sill from water by placing a waterproof tray, saucer, or piece of plastic underneath the growing container. Even careful watering can create runoff.
Select Seeds for Microgreens
Use seeds sold for sprouting or microgreen production when possible. These are generally selected for quick germination and tender young growth. Do not use seeds treated with fungicides or other chemicals that are not intended for edible sprouts or greens.
Good beginner choices include:
- Radish, which grows quickly and has a peppery flavor.
- Broccoli, cabbage, and kale, which produce mild brassica greens.
- Peas, which develop sweet shoots and attractive tendrils.
- Sunflower, which has a substantial, nutty flavor.
- Mustard, arugula, and mizuna, which add spicy notes to salads.
- Basil, cilantro, and beets, which are flavorful but usually slower to germinate.
Choose one variety for your first tray so you can learn its growth pattern. Mixed packets are convenient, but varieties may germinate and mature at different rates. If you want a blend, combine seeds with similar growth speeds and expected harvest times.
Avoid planting ordinary garden seed too densely. Microgreens are harvested young, but overcrowding can restrict airflow and encourage mold. Follow the seed packet’s suggested rate when available; otherwise, aim for a fairly even layer in which seeds are close but not piled on top of one another.
Gather Your Supplies
You do not need a specialized indoor garden system. A basic setup includes:
- A shallow tray or food-safe container about 1–2 inches deep.
- Drainage holes in the growing container.
- A second tray or saucer to catch water.
- Seed-starting mix, coconut coir, or another clean, fine-textured growing medium.
- Microgreen seeds.
- A spray bottle or small watering can with a gentle stream.
- A clean pair of scissors or kitchen shears.
- A clear lid, humidity dome, or loose plastic cover for germination.
A reused takeout container can work if it is food-safe, cleaned thoroughly, and modified with drainage holes. Make sure the edges are not sharp. Do not use containers that previously held chemicals or materials that could contaminate the crop.
A humidity cover is helpful but not essential. If you use plastic wrap, leave room for air exchange and remove it as soon as the seedlings begin pushing against it. Constantly sealed, wet conditions make fungal problems more likely.
Prepare the Growing Medium
Fill the tray with approximately 1 inch of moistened growing medium. The surface should be level, but it does not need to be perfectly smooth. Break up large pieces so delicate roots can spread easily.
Water the medium before sowing rather than trying to saturate it after the seeds are in place. Add water gradually and mix or stir the medium until it feels evenly damp. It should hold together lightly when squeezed, but it should not release a stream of water.
Do not pack the medium firmly. Compacted material drains poorly and can leave roots short of oxygen. Gently level it with your fingers or a clean piece of cardboard.
If you are using coconut coir, hydrate it according to the package directions and allow excess water to drain. If you are using potting mix, choose a fine seed-starting blend without large chunks of bark or fertilizer pellets. Garden soil is usually heavier and may contain weed seeds or organisms you do not want indoors.
Sow and Cover the Seeds
Scatter the seeds evenly across the surface. Large seeds such as peas and sunflowers can be spaced with a little more room, while tiny brassica seeds can be spread more closely. Avoid creating thick piles, because seeds touching one another stay wet longer and reduce airflow.
Press the seeds gently into the surface so they make good contact with the damp medium. Add a very thin layer of medium over seeds that require darkness or are large enough to be covered. Many small seeds can simply remain on the surface. Check the packet for variety-specific guidance.
Mist the surface carefully or water from the bottom. To bottom-water, place the growing tray inside a larger tray containing a small amount of water and allow the medium to draw moisture upward for several minutes. Remove the inner tray afterward so it is not standing in water.
Cover the tray loosely with a humidity dome or clear lid. Place it in a warm, dim, or indirectly lit location while the seeds germinate. The exact timing varies by crop, but many microgreens sprout within two to five days.
Check the tray at least once each day. The medium should remain damp, not waterlogged. If the surface begins to dry, mist it lightly. Once most seeds have germinated and the seedlings start lifting the cover, remove the lid and move the tray to its brightest location.
Care for Growing Seedlings
After germination, light and airflow become especially important. Place the tray close to the window without allowing leaves to press against cold glass. Rotate the tray every day or two if the seedlings lean toward the light.
Water when the surface looks lighter in color or feels barely damp. The best method depends on the container:
- For trays with drainage holes, bottom-water gently and allow excess water to drain completely.
- For very shallow containers, mist lightly when needed, taking care not to create standing water.
- For dense crops, water slowly around the base rather than blasting the leaves with a strong stream.
A windowsill can dry more quickly than an indoor shelf because sunlight warms the container. Check moisture at least once daily, and check twice daily during hot, dry weather. Do not follow a fixed schedule blindly; the tray’s weight and surface condition are better guides.
Provide gentle air circulation. A nearby fan set on low can reduce stagnant humidity, but do not aim a strong stream directly at the seedlings. Open the window only when outdoor conditions are suitable and the temperature will not shock the crop.
Microgreens usually do not need fertilizer before harvest. They grow from the energy stored in the seed, and most are harvested before nutrient deficiencies become significant. Adding strong fertilizer can burn young roots, create unpleasant residue, or encourage excessive soft growth.
A Simple Windowsill Schedule
The following schedule is a useful starting point, although variety and indoor conditions will change the timing.
| Stage | Typical timing | What to do |
|---|---|---|
| Prepare and sow | Day 0 | Moisten medium, spread seeds, cover lightly if needed |
| Germination | Days 1–5 | Keep evenly damp and covered loosely |
| Uncover | Days 3–7 | Move seedlings to bright light and improve airflow |
| Active growth | Days 5–14 | Water as needed and rotate the tray |
| Harvest | Days 7–21 | Cut above the medium when greens look developed |
Some crops, especially basil, cilantro, and beets, may take longer. Peas and sunflowers may need soaking first, while small brassica seeds generally do not. If the seed packet recommends soaking, use clean water and do not leave seeds submerged longer than advised.
Know When to Harvest
Harvest when the seedlings have developed their first true leaves or while they are still at the cotyledon stage, depending on your flavor preference. Cotyledons are the first smooth seed leaves. True leaves appear afterward and often resemble the mature plant’s foliage.
For most crops, the best time is when the stems are upright, the leaves are fully open, and the greens have reached roughly 1–3 inches tall. Taste a small sample before cutting the entire tray. Younger greens are often more delicate, while older ones may have stronger flavor and tougher stems.
Harvest with clean, sharp scissors. Cut just above the growing medium, leaving soil or coir behind. Do not wash the entire growing medium into your food. If the greens are clean and dry, use them immediately. If rinsing is necessary, rinse briefly in cool water and dry thoroughly, because wet greens spoil faster.
Microgreens are generally best eaten soon after harvest. Store unwashed greens in a breathable container lined with a paper towel, refrigerate them, and replace the towel if it becomes damp. Harvest only what you expect to use when possible.
Most microgreens regrow poorly after cutting because the growing point has been removed. Treat the tray as a single harvest unless a particular crop is known to produce additional shoots.
Troubleshoot Common Problems
Seeds do not germinate: The seeds may be old, the medium may be too dry, or the temperature may be unsuitable. Recheck seed age, maintain even moisture, and move the tray away from a cold window or hot appliance.
Seedlings are tall, pale, or leaning: They need more light or are too far from the window. Move them closer to the brightest safe location, rotate the tray, or add a grow light. A very crowded tray can also produce weak stems.
The surface is fuzzy or smells sour: This may indicate mold or excessive moisture. Improve airflow, remove the cover, reduce watering, and discard heavily affected trays rather than eating questionable growth. Fine root hairs can sometimes look fuzzy, especially on radish seedlings, but they usually disappear when the roots are rinsed and do not smell unpleasant.
Seedlings collapse at the base: Overwatering, poor drainage, contaminated medium, or stagnant air may be responsible. Empty standing water, improve ventilation, and use a clean container and fresh medium for the next sowing.
The tray dries out quickly: Use a slightly deeper tray, increase the frequency of checks, or bottom-water. Avoid placing the container directly above a radiator or in intense afternoon heat.
Leaves turn yellow: The crop may be staying too wet, receiving insufficient light, or experiencing a nutrient issue if it has been growing unusually long. Check drainage and light first. Most harvest-ready microgreens do not need added fertilizer.
Safer, More Reliable Growing Habits
Wash your hands before handling seeds and harvested greens. Clean trays between uses with hot, soapy water and let them dry fully. Use clean scissors and avoid letting pets, dirty cloths, or household chemicals contact the growing area.
Do not eat microgreens that are slimy, foul-smelling, visibly moldy, or contaminated with soil or cleaning products. If you are growing greens for someone pregnant, elderly, immunocompromised, or otherwise medically vulnerable, ask a healthcare professional about appropriate food-safety precautions and consider using especially clean, controlled methods.
For a steady supply, sow a new small tray every few days rather than planting one enormous tray. Radish and broccoli can provide quick harvests, while peas, sunflower, basil, and cilantro help vary texture and flavor. Label each tray with the variety and sowing date so you can compare results and repeat the combinations that perform best on your particular windowsill.