A sunny windowsill can grow a small tray of greens, but dependable microgreens do not require perfect weather or a large garden. This indoor microgreen growing guide focuses on the few decisions that make the biggest difference: choosing seeds that suit tray growing, keeping moisture even, providing enough light, and harvesting before quality slips.
Microgreens are young vegetable and herb seedlings harvested shortly after their first seed leaves open, or just as their first true leaves begin to appear. They are not sprouts. Sprouts are typically grown and eaten with the seed and root, while microgreens are grown in a shallow medium and cut above the surface. That difference matters for flavor, texture, and food handling.
Indoor Microgreen Growing Guide: Begin With the Right Seeds
Nearly any edible leafy crop can be tested as a microgreen, but not every seed produces an equally satisfying tray. For a first crop, choose varieties with reliable germination, quick growth, and a strong but pleasant flavor. Seed should be untreated and intended for edible growing. Avoid planting seed that has been chemically treated or packaged solely for ornamental use.
Radish is one of the easiest places to start. It grows quickly, has sturdy stems, and brings a peppery bite to salads and sandwiches. Broccoli and kale provide a mild, familiar flavor and are popular for everyday use. Pea shoots are sweeter and more substantial, though they need a deeper tray and a few additional days. Sunflower produces a crisp, nutty shoot but benefits from careful rinsing and good air movement because its larger seeds hold moisture.
For growers who want variety on the counter, these are dependable choices:
- Radish for a fast crop with bold flavor
- Broccoli or kale for mild, tender greens
- Peas for sweet shoots and more volume per tray
- Sunflower for crunchy, filling greens
- Cilantro, basil, or beet for slower-growing specialty trays
Set Up a Simple, Repeatable Growing Space
You do not need a greenhouse to grow microgreens indoors. A shelf, spare counter, or utility-room table can work well if the area stays reasonably warm and has access to light. Most seeds germinate well around 65 to 75 degrees F. Cooler rooms slow the crop; excessive heat encourages uneven growth and can invite mold.
Use shallow trays with drainage holes for the growing tray and a solid tray underneath to catch water. Standard 10-by-20 nursery trays are useful when producing several crops at once, but smaller trays are practical for a household harvest. Clean trays before each planting. Leftover roots and soil can carry disease from one crop to the next.
For growing medium, use a fine seed-starting mix, coconut coir, or another clean medium made for food crops. Fill the tray with about 1 to 1 1/2 inches of moistened medium, then level it gently. The surface should be even enough that seedlings emerge at the same height. Do not pack it tightly. Roots need both moisture and air.
Light is where many indoor growers underperform. A bright window may work in late spring or summer, but winter light is usually too weak for compact, richly colored greens. A simple LED grow light provides more consistent results. Position the light close enough to prevent stretching, generally a few inches above the canopy, while following the fixture manufacturer's guidance. Aim for 12 to 16 hours of light each day.
How to Sow for a Full, Clean Tray
Microgreens are planted more densely than garden vegetables, but overcrowding is not a sign of a productive tray. If seeds pile on top of one another, air cannot move through the crop and stems may stay wet. That raises the risk of mold and weak growth.
Scatter seed evenly across the damp surface, then press it lightly into place. Most small seeds need no soil covering. Larger seeds, such as peas and sunflower, can be covered lightly or simply pressed into the medium. Some growers soak large seeds for 6 to 12 hours before sowing to speed germination. That is helpful for peas and sunflower, but do not soak tiny seeds, which can clump and become difficult to spread evenly.
Mist the surface after sowing, then cover the tray with another empty tray or a humidity dome for the blackout period. Darkness and light pressure encourage many crops to root and emerge evenly. Keep the cover on for roughly two to four days, checking once daily. As soon as most seedlings are pushing upward, move the tray under lights. Leaving it covered too long creates pale, stretched stems and increases moisture problems.
Water From Below and Watch the Surface
The most common microgreen mistake is watering too often from above. Frequent misting can splash soil onto leaves, flatten young stems, and keep the crop canopy damp. After germination, bottom watering is usually the cleaner method. Add a small amount of water to the solid tray beneath the growing tray and let the medium draw it up for 10 to 20 minutes. Remove standing water afterward.
The goal is evenly moist medium, not a soaked tray. Lift the tray to judge its weight, touch the surface, and watch the seedlings. If the medium is pulling away from the edges or the tray feels unusually light, it needs water. If it feels heavy and the surface remains dark and wet all day, wait.
Good air circulation is equally useful. A small fan set on low nearby can reduce stagnant humidity, especially when growing several trays on a shelf. The fan should move air around the plants, not blast them hard enough to dry out the medium or bend the stems.
A little white fuzz at the root zone is not always mold. Many crops form root hairs, particularly when the medium is moist. Root hairs are concentrated around roots and often disappear after watering. Mold usually spreads across the surface or up stems, looks web-like, and may carry an unpleasant smell. If mold appears, improve airflow, reduce watering, and discard heavily affected trays rather than trying to salvage a crop for eating.
Harvest at the Best Flavor Stage
Most radish, broccoli, kale, and similar brassica microgreens are ready in 7 to 14 days. Pea shoots often take 10 to 16 days. Timing depends on seed type, temperature, light, and how dense the tray was planted, so appearance is more useful than a calendar alone.
Harvest when stems are upright, leaves are fully opened, and the greens look fresh and dry. Use clean scissors or a sharp harvest knife to cut just above the growing medium. Cutting too low brings soil and seed hulls into the harvest. For the cleanest result, avoid watering immediately before cutting.
Rinse only if necessary, then dry thoroughly. Excess water shortens storage life. Store harvested microgreens loosely in a clean container in the refrigerator and use them within several days for the best texture. Their flavor is strongest when they go from tray to plate quickly.
Most microgreen trays are grown for a single harvest. Pea shoots may regrow once, but the second cutting is usually smaller and less uniform. Reuse the tray, not the exhausted medium. Compost the roots and used mix if possible, wash the equipment, and start a fresh planting.
Plan Small Successions Instead of One Large Crop
A single large tray can produce more greens than a household uses before quality declines. For steady harvests, sow one or two small trays every week. That approach also spreads risk. If one tray gets too dry, develops poor germination, or is harvested early, you still have another crop coming along.
Keep a simple note with the seed variety, sowing date, blackout date, and harvest date. After a few rounds, you will know which varieties your household enjoys and which ones fit your space. Growers raising microgreens for a market table or local accounts can use the same records to estimate tray yields and schedule production with more confidence.
Start with one dependable crop, learn how your indoor space behaves, then add another tray the following week. A clean setup, quality seed, and consistent observation will take you farther than a complicated system ever will.