Growing Microgreens on a Windowsill

What Are Microgreens — And How Do They Differ From Sprouts?

Microgreens are young vegetable or herb seedlings harvested shortly after the seed leaves (cotyledons) unfold, often just as the first true leaves are starting to show. They're sown thickly into a shallow layer of compost or a damp mat, and the whole process happens indoors, whatever the season.

Microgreens are often confused with sprouts, but they're not the same thing. Sprouts are grown in water without soil or light and eaten whole, including the seed and root. Microgreens are grown in light, cut above the soil line, and only the stem and leaves are eaten. Baby leaf — the pre-washed salad mix at the supermarket — is a further stage on and closer in size to a full-grown lettuce; our guide to growing lettuce is a natural next step if that's where you're headed.

Microgreens, Sprouts or Baby Leaf?

What Do You Need to Grow Microgreens on a Windowsill?

The list is short, and you probably already have most of it:

• Seed labelled for microgreens, sprouting or food use – see the next section on why that matters.
• A shallow container, about 3–5 cm (1–2 in) deep, with drainage. An old baking tin, a seedling tray or a purpose-made microgreens tray all work.
• Seed compost, coconut coir or a ready-made growing mat. If you're not sure which to pick, our guide to the best seed compost covers the options.
• A spray bottle or a watering can with a fine rose.
• A bright windowsill, ideally facing south or west.
• Optional: a simple grow light for the darker months – more on that below.

Good to know. You don't need a purpose-made tray. A clean plastic tub with a few drainage holes poked in the bottom with a hot needle works just as well as anything sold specifically for microgreens.

Compost, Coir or a Mat — Which Should You Use?

Ordinary seed compost is cheapest and easiest to find, but should be labelled for sowing so it doesn't carry weed seed or fungal spores. Coconut coir is cleaner and holds moisture more evenly, though it usually needs soaking and breaking up before use. Hemp or cellulose growing mats are the easiest to keep clean and simply get thrown away after each batch, but cost more per tray and can give fine seed slightly less contact with moisture if they aren't thoroughly dampened first.

Which Seeds Should You Choose — and Which Should You Avoid?

Because you're eating the entire young plant, stem and leaves included, seed choice matters more for microgreens than it does for ordinary vegetable growing, where only the mature fruit or root ends up on the plate.

Use seed labelled for microgreens, sprouting or food use. Ordinary seed bought for transplanting outdoors, particularly seed potatoes and some bulk vegetable seed, can be treated with fungicide — a perfectly reasonable choice for a plant that will spend a whole season in the ground, but not something you want on a shoot you're cutting and eating after a week.

Organic seed isn't essential, but it rules out chemical seed treatment by definition and is a straightforward default if you're unsure what a particular packet has been treated with. Test the germination rate on older seed with a small trial batch before committing a full tray — if fewer than half the seeds come up, it's time to buy fresh.

Good to know. Seed sold specifically for microgreens is often cheaper per gram in bulk than ordinary seed packets, since you go through far more seed per tray than you would sowing individual plants.

How to Sow Microgreens Step by Step

The method is largely the same across varieties, with a few exceptions for pre-soaking. If you've already started seedlings indoors for the vegetable garden, the routine will feel familiar — see our guide to starting seeds indoors for more on growing under cover generally.

1. Soak larger seed. Pea shoots, sunflower shoots and other large seed germinate faster after 6–12 hours in water. Small seed such as radish, mustard and broccoli doesn't need soaking.
2. Fill the tray. Add a 2–3 cm (about 1 in) layer of moist seed compost or a growing mat, and level the surface without packing it down hard.
3. Sow thickly. Scatter seed evenly and densely across the surface, close enough that it almost touches. Press gently with your palm so the seed makes good contact with the medium.
4. Keep it dark and damp. Cover the tray with a lid, a plate, or another tray turned upside down, and keep it somewhere cool and dark for 3–5 days. Check daily that the surface hasn't dried out.
5. Move it into light. As soon as you see pale shoots lifting the cover, remove it and move the tray to the brightest windowsill you have.
6. Water from below. Stand the tray in a few centimetres of water for 5–10 minutes, or water carefully at the edge so you don't dislodge the seed.
7. Harvest with scissors. Once the first true leaves start to show, usually 7–21 days after sowing, snip the shoots just above the soil line.

As a rough guide, about 10–15 g of seed covers a standard 20×20 cm (8×8 in) tray for fine seed such as radish, mustard and broccoli. Larger seed like pea and sunflower shoots germinates at a lower density per gram and often needs 30–40 g for the same area.

How Much Light Do Microgreens Need on a Windowsill?

A bright summer windowsill is often enough light on its own. The problem is the darker months — anyone gardening in USDA zones 3–6 or at similar latitudes knows how short and weak daylight gets from late autumn through winter, and a north-facing or shaded window makes it worse.

Microgreens do best with 12–16 hours of light a day once they've germinated. Fall short, and the shoots turn long, pale and leggy — a sign they're stretching toward the light, known as etiolation (more in the troubleshooting section below). A simple LED grow light running a few hours morning and evening through winter is often the difference between thin, washed-out shoots and compact, green ones. If your other windowsill seedlings struggle through winter too, our guide to grow lights for seedlings is worth a read.

Look for a grow light rated at least 3000–4000 Kelvin — a neutral white light rather than the purple glow of some dedicated grow lamps — and position it 15–30 cm (6–12 in) above the shoots. Too far away gives the same pale result as too little natural light; too close risks scorching the delicate leaves.

How Often Should You Water Microgreens?

Microgreens have extremely shallow roots, so the growing medium dries out fast — but overwatering from above is the single most common cause of mould. Water from below when you can: stand the tray in a few centimetres of water so the medium draws up what it needs by capillary action, then tip out any excess after 5–10 minutes.

During germination, before you remove the cover, checking once a day is usually enough. Once the shoots are in light and growing in earnest, a warm, dry windowsill may need watering both morning and evening. Test the surface with a finger before watering again — microgreens should never sit in standing water. The same basic principle applies to most houseplants; see our guide on how often to water plants if you want to go deeper.

Which Varieties Are Best for Beginners?

Not every variety germinates at the same speed, and some are far more forgiving than others. The chart below shows approximate timing for the most common microgreens.

Radish, mustard and broccoli are the most forgiving varieties to start with — they germinate fast, rarely have mould trouble, and taste distinct enough that you'll know quickly whether you got it right. Basil is fun but notoriously uneven to sow; it's worth waiting until you've got the routine down with the easier varieties first.

Skip these as microgreens. Leaves from tomato, potato, pepper, chilli and aubergine (the nightshade family) can contain compounds that are unsafe in quantity and shouldn't be grown or eaten as microgreens, even though the fruit itself is completely safe to eat.

Harvesting and Storing Microgreens

Cut with sharp scissors or a knife just above the soil line, ideally just as the first true leaves start to show. Wait too long and the flavor sharpens and the stems toughen; cut too early and you'll get less volume and a weaker taste.

Most varieties won't regrow after cutting, since the seed's entire energy reserve is already spent. Pea shoots and some beans are the exception and can give a smaller second cut. Otherwise, plan on sowing a fresh tray every week if you want a steady supply.

Rinse the harvest in cold water right before you use it, not straight after cutting – moisture shortens shelf life. Kept dry in a jar or bag with a piece of paper towel, most microgreens stay fresh in the fridge for up to a week.

Is Growing Your Own Microgreens Worth It?

A small punnet of fresh microgreens at the supermarket often costs several dollars for just a few grams. A seed packet in roughly the same price range typically stretches to several sowings with a much bigger yield, even once you factor in compost and a basic tray.

The bigger win usually isn't the money – it's skipping the plastic packaging and being able to cut exactly what you need the same day you cook, since microgreens lose a lot of flavor and nutritional value within a few days of being cut.

The time investment is small too. Budget a few minutes for sowing and about a minute a day for watering, against a growing time of 1–3 weeks depending on variety.

Common Mistakes

• Sowing too thinly. Microgreens need a much denser sowing than ordinary seed – thin, spaced-out rows give weak, isolated shoots instead of the dense green carpet you're after.
• Watering from above too often. Persistent surface moisture is the most common route to mould. Water from below when you can.
• Leaving the cover on too long. Forget to remove it once the seed germinates and the shoots turn pale and leggy before you've even noticed.
• Reusing compost without cleaning the tray. Old compost can carry mould spores from the last batch.
• Mixing too many varieties in one tray. Different varieties germinate at different speeds – combine them and you'll miss the right harvest window for at least one.
• Harvesting too early out of impatience. Wait until the first true leaves are showing, or you'll end up with weak flavor and a disappointing yield.

FAQ

Can you grow microgreens without soil?
Yes. Coconut coir and growing mats made from hemp or cellulose work just as well as compost and are easier to keep clean. The seed carries enough stored energy for the whole growing period, so you don't need to feed either medium.

How long do microgreens keep in the fridge?
Stored dry and unwashed in an airtight container or bag with a piece of paper towel, most varieties stay fresh for about a week. Don't rinse them until right before you eat them, since moisture speeds up spoilage.

Do microgreens regrow after cutting?
Most varieties don't, since the seed's stored energy is already used up by the time you cut. Pea shoots and some beans can give a smaller second harvest, but plan on resowing for most other varieties.

Are microgreens and sprouts the same thing?
No. Sprouts are grown in water without light and eaten whole, including the root and seed, while microgreens are grown in compost or a mat, given light, and only the stem and leaves are harvested.

Do microgreens need fertilizer?
No. Over such a short growing period, the nutrients stored in the seed are enough on their own. Feeding makes little difference and can even raise the risk of mould by encouraging bacterial growth in damp compost.

Which window position works best?
A south- or west-facing window usually gives the most light. A north-facing window still works but often produces weaker shoots in winter, when a simple grow light can make a real difference.

Can you grow microgreens year-round?
Yes – that's one of the biggest advantages, since the entire process happens indoors and isn't affected by weather or season. In winter you'll usually need to supplement daylight with a grow light to avoid pale, leggy shoots.

Is homegrown microgreens safe to eat raw?
Yes, as long as you keep the tray and growing medium clean and avoid growing nightshade-family plants such as tomato, potato, pepper and eggplant, whose leaves can contain harmful compounds. Rinse the harvest in cold water before eating, especially if you grew it in ordinary compost.

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