Growing microgreens inside or out

As time goes on and I continue to neglect this blog, I keep learning new techniques, experimenting, and thinking, “this would be really great to post…” but never doing it. With that in mind, I bring you some practical knowledge I’ve fostered this winter.

I’ve been leading some workshops on “winter gardening” in the past few months, focused mostly on growing microgreens, which, if you don’t know, are the first true leaves of a seedling. Also known as cotyledons. Microgreens can be any of several plants — beets, chard, radishes, arugula, broccoli, Asian greens, spinach, mizuna, the list goes on — harvested and eaten before they have the chance to grow past that first seedling stage.

Microgreens are delicious, super nutritious (broccoli sprouts are supposed to be a cancer fighting superfood), and possibly the easiest thing to grow inside. In December, I became convinced that I could grow microgreens at home, in my bedroom — and after a few experimental trays, I proved myself right. The weather is turning and I don’t think anyone could call in winter anymore, but you can still grow these delicious little greens inside (and out)…

Most of the techniques I describe here can also be used to start seedlings inside for your garden this season, with a few variations.

My first sad, spindly shoots

The best advice I can offer for growing inside, the thing I must stress the most, is lighting lighting lighting. I tried to grow these little guys by a south-facing window and it just didn’t work. The seedlings were long and spindly, kept reaching toward the light but were never able to get enough. I discovered that this is because glass windows scatter the small amount of natural light beaming in from outside. A greenhouse works because it’s made of special material that doesn’t do this.

So how to light? The best value lightbulb you can get for a makeshift grow light is a cool white fluorescent. They cost $3 each at your local hardware store, and are ideal for green growth, which is all you need for microgreens and shoots (slightly bigger than “micro,” often a pea or sunflower plant). The way I light my plants (pictured here) is with one of these lightbulbs along with a reflector, also purchased at the hardware store, maybe $6.

my beautiful, functioning light set-up

The light should be on 12-14 hours a day. Since mine are in my bedroom, I turn the light on when I get up and go to work and turn it off when I go to sleep. It’s not an exact science. You can also use a timer if you’d prefer not to think about it. Obviously, if you’re growing outside, don’t worry about lighting — the sun will provide.

Containers. Since I’m lucky enough to have access to plant propagation trays, I use those for my microgreens. They’re simple black plastic trays with some holes in the bottom that are meant to be filled with soil and sown with seeds. These are available lots of places — garden stores, online — but if you have an extra take-out or yogurt container, you also don’t really need one. Just wash it out, poke some holes at the bottom, and you’re good to go.

black plastic tray

I’ve always heard that drainage is important. You can use any of a variety of containers to grow plants, but making sure that there are holes on the bottom is key. As a disclaimer, a friend did tell me she grew microgreens in a frisbee this winter — no holes — and it worked fine.

For starting seeds, it’s convenient for transplanting purposes to use trays with cells, or, if you’re being creative, things like used little yogurt containers and egg cartons.

SoilYou only need an inch or two of soil — no need for the 6 inches or so suggested for container gardening of mature plants. Since you’re harvesting at a stage where seedlings are small, root development doesn’t really become an issue. If you’re growing inside, use potting soil, as pure as you can find. The soil from outside in your garden has microbes in it that interact with their outside environment but that won’t fit with an inside one. That being said, I see no harm in trying it. If it fails, you’ve only lost a week or two in microgreen production.

The soil situation with seed starting is the opposite, because root development is very important. If you’re starting seeds, use plenty of soil.

Watering. Water your greens every few days — keep the soil moist, but not saturated. Best methods are a fine mist watering can, spray bottle, or bottom watering: putting a tray under your container, putting water in the tray, and leaving it there for 45 minutes or so.

Harvesting. Last time, I harvested my greens after a week. Literally seven days. Cut off toward the base of the stem, being careful not to get any dirt, with a pair of scissors. Empty your tray into the compost bin, add new soil and plant again — you’ll have new greens for next week in no time! And in the meantime, make a salad, top a burger, and make pesto.


About PRI Cold Climate

PRI Cold Climate is an organization centered in Minneapolis that promotes permaculture throughout the region, fostering sustainable lifestyles and communities. We design and demonstrate permaculture systems specific to colder climates like ours, and provide leadership and resources for the permaculture community.
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3 Responses to Growing microgreens inside or out

  1. E.A.Davis says:

    Thanks for the post! Although, I do wish I could have read it earlier, say November. Then I could’ve practiced my own micro-green production this winter!
    One question, would you say I would still need to use topsoil if I can just innoculate topsoil with vermicast from my worm bin?

  2. Hey, there’s always next year. Or anytime, really — just takes a week. For me it was really an experimental process this winter… I say try the topsoil with vermicast and see how it goes… and let me know!

  3. robertred says:

    I just learned how to grow microgreens. Thanks for sharing this article and I appreciate your insights.

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