How to Grow Microgreens Indoors (UK Beginner's Guide)

Microgreens are young vegetable and herb seedlings, harvested just after the seed leaves (the cotyledons) open and the first true leaves begin to show, usually when the plants are 3-8 cm tall. They sit between a sprout, which is eaten whole after a few days including the root, and a baby leaf, which is grown on for several weeks. You snip microgreens off at soil level and eat the tender stems and leaves raw.

They earn their windowsill space for more than novelty. A widely cited study from the University of Maryland found that many microgreens carry higher concentrations of vitamins and carotenoids than the same plants grown to maturity, in some cases around five times more (University of Maryland, 2012). For a plain-English primer on what does and does not count as a microgreen, the Wikipedia entry on microgreens is a solid starting point.

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

• A shallow tray with drainage. A seed tray works, but a clean takeaway container or fruit punnet with a few holes poked in the base is fine.
• A growing medium. Peat-free multipurpose compost or coir (a coconut-fibre growing medium) both work well. You only need a thin 2-3 cm layer.
• Seed. You can buy dedicated microgreen or sprouting seed, or use ordinary vegetable seed bought in bulk. Because you sow so densely, buying larger packets keeps the cost down.
• A spray bottle for gentle, even watering.
• Light. A bright windowsill for most of the year, or a small LED grow light for dim rooms and midwinter.

No heat mat, no propagator, and no fancy equipment are required to get a first tray going.

Start with fast, forgiving varieties before you branch out:

• Radish is the classic first crop: it germinates in a day or two, grows vigorously, and is ready in about a week with a pleasant peppery bite.
• Pea shoots are sweet and crunchy, ready in 10-14 days, and the one common microgreen that reliably gives a second cut.
• Broccoli and kale are mild, nutritious brassicas that grow evenly in 10-14 days.
• Sunflower gives thick, nutty shoots; soak the large seeds overnight first.
• Mustard and cress are among the fastest of all and great for children to grow.

Leave the tricky ones until you have a few trays behind you. Mucilaginous seeds such as chia, basil and rocket form a jelly-like coating when wet and need a firmer surface and misting rather than watering, so they are easier once you know the rhythm.

Less than you might think. A bright windowsill is usually enough, even a north-facing one, because you harvest microgreens long before they need strong light to flower or fruit. South- or west-facing sills give faster, sturdier growth.

In a dim room or through the darkest UK winter weeks, a small LED grow light run for 12-16 hours a day stops shoots going pale and leggy. If you want to understand why the colour of that light matters, our guide to grow-light spectrum explains it simply. Microgreens are also one of the best crops for a genuinely low-light spot, which is why they feature in our north-facing balcony planting list.

Little and often is the rule. During the blackout period, mist to keep the surface damp. Once the tray is uncovered, water into its base every day or two so the compost stays evenly moist.

The biggest beginner mistake is overwatering, which invites mould and damping off (a fungal collapse of seedlings at soil level). Watering from below, giving the tray some airflow, and not sowing quite so thickly next time prevent almost all of it.

Most microgreens are ready 7 to 21 days after sowing, once the cotyledons have fully opened and the first true leaves are showing. Snip a handful at a time just above the compost with clean scissors, rinse, and eat within a few days for the best texture and flavour.

Despite the name, most varieties are not cut-and-come-again: you take one main harvest, then compost the spent roots and re-sow. Pea shoots are the reliable exception. Leave 2-3 cm of stem and many will push out a lighter second cut before they tire.

For most growers, yes, and by a wide margin once you are past the first sowing. A shop-bought punnet holds only a small handful and is priced at a premium per gram. A single seed packet, sown densely, fills a whole tray, and buying sprouting seed in bulk brings the cost per tray down further still.

The only ongoing costs are seed and a little compost. A windowsill needs no electricity at all, and even a small grow light draws just a few watts. Set against the price of the punnets you would otherwise buy, a tray typically pays for itself within its first couple of cuts.