While I was staying in London last month, I had the opportunity to go on a guided tour of a hydroponics company, Growing Underground. They literally do grow underground, in tunnels underneath Clapham Common, paralleling the Northern Line, originally designed as possible air raid shelters. They supply around 40 supermarkets at the moment, nearly all of them in London, so the food miles are minimal, and the products are tasty – zingy, chewable and you can just feel all the nutrients being absorbed into your system. The scale is amazing, and of course they’re expanding all the time: more varieties and mixes, different hydroponic solutions, different lights, different markets. It’s wonderful, and it employs maybe a couple of dozen people. This is the tour group I went round with:

My tour group

It made me enthusiastic about microgreens all over again, so I set up an experiment once I got home. I wasn’t as scientific about it as I could have been, but it convinced me that I could certainly grow a couple of portions of green veg every day, only limited by the amount of seeds.

I’d already set up a little home-made microgreens kit, which I’d put by so that I could start it up quickly if need be: just some supermarket trays that had held fresh veg, some seeds and a couple of litres of bought-in topsoil nearby. The results were even better than I’d hoped, though I’ll run the experiment again in a more measured way, so that the number of seeds is constant, for instance.

Here’s my conclusions:


I have a tendency to drown indoor plants, but I did really well with these:

  • watered once and covered them with a paper towel for 3 days, until they were properly poking their heads above the soil.
  • When I watered them subsequently, I used a small, purpose made watering can with a rose on it, instead of an ordinary kitchen jug – for people who over-water, this is a seriously brilliant idea.


I didn’t use expensive seeds, I used green lentils from Sainsbury, £1.15 for 500g, and soaked them for 24 hours. This was almost too long, as I was just starting to see the tips of the shoots coming out. I’d go for 20 hours next time.


The supermarket trays are so easy to re-use, so accessible, and free, but they have their problems. The first harvest, because I couldn’t see the bottoms of the stems, I left them too long, they were turning brown, and I lost maybe 10% of the crop to this effect. Not important today, of course, but if I was in real need of these nutrients, that’s too much to lose. I suggest that any tray used might be better to be only about an inch high, and then you can see much more easily when you should harvesting. If they were flatter than the supermarket trays, that would help too.

First harvest at home


This was great, because I ended up treating them as cut and come again plants – the same little tray got me a total of four harvests, just roughly chopped up and sprinkled over pasta or something. It certainly felt like a proper portion-of-fruit-and-veg, not just a little sprinkle.

Growing Medium

Just an inch or so of a bog standard potting mix from any big store – B&Q, Wickes, Wilko, Poundland, whatever’s easily available to you. At Growing Underground, they use a hydroponic liquid circulating through a kind of web of filaments made locally from recycled carpet, and after being used for a while, they’re transported a few miles to a biomass power plant and used for fuel. My equivalent of supermarket topsoil is now sitting in my compost bin, of course.

Plant Protection

If you look online, you can see that people grow in propagators, to avoid draughts and keep a better, more even heat for the plants. I didn’t use any for this experiment, and these days, with the extremes of temperature we’ve been having, I think you’d need to be very proactive about taking the protection on and off, so that the little microgreens don’t die from overheating.


LED lights are also popular. I didn’t use any, but having a set overhead would extend your ability to grow more food more quickly. Nor would you have to turn your tray so often to catch the light coming through the window. They can get really expensive, really fast, but I’ll certainly be buying a bulb, one that fits an ordinary lamp.

All in all, I’m very happy with the experiment, though I’m less happy with the amount of time it’s taking me to learn the latest WordPress upgrades. At least I can get images again: here’s a nice one of a portion-sized helping of microgreens.

The finished article

May all your Microgreens be Marvellous.

4 thoughts on “Microgreens

  1. Some great pointers there.I am looking at microgreens myself for Autumn/Winter.The idea of cut and come is inspired; that makes it a really worthwhile project.Thank you.

    1. Thanks Jansman! I think a supply of quickly grown greenery, independent of the weather, could be a real boon to a prepper during, say, a series of bad winter storms, or a pandemic. If i was growing them regularly, I’d set up more carefully, but this was the proof of concept for me, and I’m really happy with it.

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