How to Grow Microgreens, Herbs and Salad Indoors in Winter

Salad leaves, herbs and microgreens are among the easiest crops to keep going indoors through a UK winter: picked young, they need less light than a fruiting plant. This guide covers microgreens on a tray, herbs and salad in pots, on the Autopot Tray2Grow or in a small NFT system. The lights are in our propagation lighting section, the tanks in NFT systems.

What to grow

Microgreens are seedlings cut whole at the seed-leaf stage, as a rule of thumb one to three weeks after sowing; salad leaves and soft, leafy herbs grow on a few weeks longer and are picked leaf by leaf, cut-and-come-again: they are generally the easiest, where woody herbs want more light and drier roots. From October to March a windowsill gives only weak light, so a grow light on a timer replaces the day.

Lights for a winter shelf

Our propagators and cuttings guide compares the propagation lights. Our advice: the Maxibright LED T5 Propagation Lights - 60cm or a chain of Gorilla Propagation LED 12W strips (lead sold separately) over microgreens and seedlings; the LUMii Switch Blade 150W or a dimmed Maxibright Daylight 200W PRO LED over salad and herbs grown on for picking. Our LED wattage guide lists both for a 60 x 60 cm space; how close to hang each, the PPFD to aim for and why plants go leggy are in our grow lights for indoor plants and seedlings guide. Hours: our advice is 18 a day on a timer such as the Time-R Digital Timer, the usual 18/6 schedule in our growers' glossary.

How to grow microgreens on a tray

Fill a seed tray with a shallow layer of moist Biobizz Light Mix or coco.
Sow thickly, press the seed in and cover the tray until the seedlings are up, then put it under the light.
Water from below: stand the tray in a garden tray of water until the surface darkens, then lift it out to drain.
Keep the air moving with a clip fan on low: damping off takes hold in damp, still air.
Cut just above the surface at the seed-leaf stage; the spring-loaded Chikamasa T-552 Scissors open after each cut. Sow a new tray each week.

Herbs and salad leaves in pots

Sow soft herbs and salad into plugs: the Plug Life 80/20 Peat Mix tray has 104 plugs; its page says to put one seed in each and keep the tray in a propagator until roots show. Pot on into 1 litre Square to Round Pots: as a rule of thumb, salad leaves picked young stay there, while herbs you keep longer go up to 2 or 3 litre, then a final pot such as the 5l Air-Pot, whose page names herbs but warns it dries out faster than a standard pot. Fill with Biobizz Light Mix (its page says to start feeding once plants are established) and pick the outer leaves so the centre grows on.

The Tray2Grow: a self-watering shelf

The Tray2Grow is an AutoPot tray with an AQUAvalve under capillary matting: fed by gravity from a raised reservoir, with no pump, timer or electricity, it waters seed trays or microherb trays; its page names microgreens, salads and herbs. Stand it level below the tank (a 47 litre tank and lid is in Autopot Accessories & AquaValves) and keep the valve clean. The Autopot Tray2Grow Planter is a fabric insert you fill with growing media and sow straight into, no pots needed. Feed through the tank with Formulex.

NFT for salad and herbs

In NFT a pump lifts nutrient solution from a tank to a tray, where it runs in a thin film over bare roots and drains back. The GT205i page calls it an ideal introduction to hydroponics: 70 x 39 x 19 cm, a 20 litre tank, Correx top plate, spreader mat, pump and pH test kit included. The Multiduct NFT 2-Channel fits a lot of plants into a narrow space in two slim channels; its page names leafy greens, herbs and other fast-growing plants, and lists eight models: call or message us for the differences.

Lay a single layer of Spreader Mat in the tray so the film spreads to every plant; a fresh one for each crop.
Fill the tank, mix the feed and check the pH: House & Garden's chart gives 5.7-5.9 for recirculating hydro and the Plant Magic Hydro A & B page 5.5-6.2, both in our flood and drain guide; Formulex usually needs no pH adjustment in tap water, its page says. To lower the pH, add Growth Technology pH Down a few drops at a time (see pH and EC meters).
Fit the Correx top plate, which keeps light off the roots, and set a rooted Rockwool Propagation Cube (25 or 36 mm) through each hole. For NFT, sow into the cubes and keep them in a propagator until roots show through, their page says; no other medium goes in the tray.
Run the pump all the time, check pH and EC every day or two (Canna Aqua Vega's EC targets are in our Canna Aqua feed chart; for Formulex, follow the label) and change the solution weekly, as our root rot guide advises.

The winter tank. The Eheim Tank Heaters page says to aim for 18-21°C; its 25 W heater covers 20-25 litres, the GT205i's tank.

Feeds for leafy crops

Feeds for herbs and salad, as their product pages describe them.
Feed	For	Dose and pH
Formulex	Hydro or soil; a full-cycle feed for herbs and leafy greens	At the rate on the label; about pH 6 in tap water
Canna Aqua Vega	Recirculating NFT; buffers hold the pH	2.1-3.6 ml per litre of each part; never mix A and B neat
Biobizz Grow	Soil; organic, NPK 4-3-6; herbs and leafy greens (or Biobizz Fish Mix, the same job)	2 ml per litre through growth in Light Mix (Biobizz feed chart)

For pests, the SB Plant Invigorator page says to spray weekly from the start at 10 ml per litre, that it is safe on edible crops, and to follow the label.

Which should I choose?

Microgreens on one shelf: the 60 cm Maxibright T5 over seed trays in a garden tray, with a clip fan on low.
Herbs and salad, no pump: the Tray2Grow, Planter and 47 litre tank, Formulex in the tank, under a Switch Blade.
Small, fast crops in a tight space, no pots to fill, as our flood and drain guide puts NFT: the GT205i with Formulex or Canna Aqua Vega and an Eheim 25 W heater, under the Daylight 200W PRO dimmed.

A ThermoPro TP358 at tray height records the lowest temperature over 24 hours; if the room is cold, see our heaters guide.

Quick answers

How do I grow microgreens at home?

Sow thickly on moist light-mix soil or coco, cover the tray until the seedlings are up, then give them 18 hours a day under a light (our advice above) and cut at the seed-leaf stage, one to three weeks on.

Can you grow herbs indoors in winter?

Yes, under a grow light on a timer: a windowsill gives too little light from October to March.

Can I grow salad leaves hydroponically?

Yes, in a small NFT system: the Multiduct page names leafy greens and herbs. Raise plants in rockwool cubes, feed with Formulex or Canna Aqua Vega and change the tank weekly.

More Growers' Guides

Not sure what you need? Call the shop on 0117 971 3000 or pop in to the Bristol store and we'll help you pick.