Your Free Indoor Microgreens Growing Guide

What Are Microgreens and Why Grow Them Indoors

Microgreens are young vegetable or herb plants harvested just 1 to 3 weeks after germination, when they are 1 to 3 inches tall. Unlike sprouts, which are eaten roots and all, microgreens are cut above the soil line and eaten as leafy greens. They are packed with nutrients—studies show microgreens contain up to 40 times more nutrients per gram than their mature plant counterparts. For example, red cabbage microgreens contain 50 times more vitamin C than mature red cabbage, and broccoli microgreens can have 50 times the sulforaphane, a compound with potential health benefits.

Growing microgreens indoors offers several practical advantages. You can grow them year-round regardless of outdoor weather conditions, in apartments without outdoor space, or in climates where outdoor gardening is limited. Indoor growing takes up minimal space—a single 10 by 20 inch tray can produce a significant harvest. The growing cycle is very short, meaning you can go from planting to harvesting in as little as 7 to 14 days for some varieties. Indoor growing also reduces pest and disease problems since the plants are not exposed to outdoor insects or fungal issues that affect outdoor gardens.

Common microgreens varieties include broccoli, radish, mustard, alfalfa, sunflower, pea shoots, and various herbs like cilantro and basil. Different varieties have different flavor profiles and nutrient contents. Radish microgreens have a peppery taste and grow quickly. Sunflower microgreens are mild and nutty. Broccoli microgreens taste like mild broccoli and are nutrient-dense. Mustard varieties range from spicy to tangy.

Practical Takeaway: Microgreens are nutrient-dense plants grown indoors in a short timeframe, making them an option for people with limited gardening space or those living in climates where year-round outdoor gardening is not feasible. Understanding which varieties suit your taste and space is the first step to planning your indoor garden.

Essential Supplies and Setup for Indoor Growing

You do not need expensive equipment to grow microgreens indoors. The basic supplies include shallow growing trays, growing medium, seeds, and a light source. Shallow trays are typically 10 by 20 inches and 2 to 3 inches deep. You can purchase purpose-made microgreen trays or use food-service containers, takeout containers, or even kitchen storage containers with drainage holes drilled in the bottom. The key requirement is that the container allows water to drain and has enough depth for roots to develop, usually at least 1.5 inches of growing medium.

Growing medium is the material in which seeds germinate and roots develop. Common options include potting soil, coconut coir, peat moss, seed-starting mix, or hemp mats. Potting soil is widely available and inexpensive, typically costing $5 to $15 per bag depending on size and quality. Coconut coir is a sustainable alternative made from coconut husks. Peat moss is fine-textured but environmentally concerns have led some growers to choose alternatives. Seed-starting mix is specially formulated for germination and contains perlite or vermiculite to improve drainage. Many growers use a 1-inch to 1.5-inch layer of growing medium per tray.

Seeds should be high-quality, untreated seeds intended for eating. Some seeds come in bulk quantities designed for microgreen production. Common seed sources include online retailers, garden centers, and health food stores. A single pound of seeds can grow multiple trays of microgreens. For example, one pound of broccoli seeds yields approximately 10 to 15 trays of mature microgreens.

Lighting is critical for healthy growth. While some microgreens can grow with indirect natural light from a window, most grow better with supplemental light. LED grow lights are energy-efficient and affordable, costing $20 to $100 depending on quality and size. A standard setup uses full-spectrum LED panels positioned 4 to 6 inches above the plants. Microgreens typically need 12 to 16 hours of light per day.

You will also need a water source for misting or watering and possibly a humidity dome or plastic cover to maintain moisture during germination. These are inexpensive items found at garden centers or online, usually costing $5 to $20.

Practical Takeaway: A basic microgreens growing setup can be created with common household items or inexpensive gardening supplies totaling $50 to $150 for a starter system. Investing in quality growing medium, untreated seeds, and LED lighting creates an environment where microgreens can thrive reliably.

Step-by-Step Growing Process and Timeline

The microgreens growing process follows a consistent pattern. Day 1 involves preparing your growing medium and planting seeds. Fill your tray with 1 to 1.5 inches of moist growing medium, pressing it gently to create a level surface. Spread seeds evenly across the surface, attempting to avoid overcrowding while achieving good coverage. For smaller seeds like broccoli or mustard, spread them in a single layer. For larger seeds like sunflower or pea, they can overlap slightly. Mist the seeds with water until the medium is moist but not waterlogged. Cover the tray with a humidity dome or plastic lid to retain moisture.

Days 2 to 4 are the germination phase. Keep the medium consistently moist but not waterlogged, as excess water can cause mold or rot. Mist once or twice daily. The tray can remain covered during this period to maintain humidity. Most seeds will begin sprouting within 2 to 4 days. You do not need light during this phase; seeds germinate in darkness. Germination temperature should be between 65 and 75 degrees Fahrenheit for most varieties.

Day 5 onward involves moving the tray to the light source. Once seeds have sprouted and the first leaves appear, remove any covering and position the tray under LED grow lights at 12 to 16 hours per day. Lights should be 4 to 6 inches above the plants and adjusted upward as the plants grow. Continue misting to keep the medium moist. At this stage, microgreens will develop their characteristic color and begin growing upward.

Days 7 to 14 are the growth phase. Microgreens will rapidly develop their first true leaves and grow taller. Continue daily watering, allowing the top of the medium to dry slightly between waterings to prevent mold while keeping roots hydrated. The exact timeline varies by variety. Radish and mustard microgreens may be ready in 7 to 10 days. Broccoli and cabbage take 10 to 14 days. Sunflower and pea shoots may take 12 to 16 days.

Harvesting occurs when microgreens have developed their first true leaves and are 1 to 3 inches tall. Use clean scissors to cut the microgreens just above the soil line. Harvest in the morning when plants are fully hydrated. Most microgreens can be stored in a refrigerator in an airtight container for 5 to 10 days after harvest.

Practical Takeaway: The complete cycle from planting to harvest typically takes 10 to 16 days depending on variety. Following the phases of germination, sprouting, and growth with proper moisture and light management produces healthy, nutrient-dense microgreens ready for consumption.

Managing Water, Light, and Environmental Conditions

Water management is the most common challenge in microgreens growing. The growing medium must be consistently moist but never waterlogged. Overwatering causes mold, mildew, and root rot. Underwatering causes wilting and poor growth. During germination (days 1 to 4), mist the tray twice daily and keep it covered. Once lights are introduced, water needs may increase. A general guideline is to water when the top of the medium feels dry to the touch, typically once daily for most setups.

The method of watering matters. Bottom watering—placing the tray in a shallow pan of water and allowing the medium to absorb moisture from below—reduces