Growing Microgreens

Article and Photos: Cathy Morison (Canberra Organic – Summer 2019 [Part I] Autumn 2020 [Part II])

Faba (broad) beans ready for harvest
Faba (broad) beans ready for harvest

Winter is normally a time for using up the pumpkins from the summer harvest and waiting longingly for the first summer garden bounty, relying on store-bought salad greens. This year I wanted to try something different to keep a steady, if reduced, winter harvest.

While doing some research on hydroponics, I was finally persuaded to investigate the option of microgreens—something that I had heard of but had not considered as something a ‘real gardener’ did. After watching a few YouTube clips on the process and the result, I was hooked.

Getting set up isn’t that complicated. You don’t need a lot of room, nor do you need to go to huge expense. Depending on the volume that you plan to create, at the very least you need some trays, a place to keep them in darkness and a place where they can be exposed to (either natural or fluorescent/LED) light.

There are quite a few varieties of seeds that lend themselves to being grown as microgreens. Some of the most popular include sunflower, radish, broccoli/kale, pea and faba (broad) beans. I have had good success with all of these, plus I also regularly grow wheat into wheatgrass (although, strictly speaking, that isn’t a microgreen crop but a juicing crop). I have also experimented (with limited success) with chickpeas, lupini beans, lentils, fenugreek, cress and coriander. These crops have tended to be either too fiddly, too prone to problems or are simply not as nice to eat.

The first part of this article focuses on how I established my microgreen garden. The second part explores the different crops. If you are interested in getting started, there is a wealth of information on YouTube that I would recommend you investigate.

Equipment

While it is not necessary to have a fully ‘kitted out’ grow room to produce microgreens, there are some ‘nice to have’ items that make it easier.

Firstly, you will need trays to grow your crop in. I have used the standard propagation flats (290mm x 350mm) — both with and without drainage holes. Some crops I find easier to grow using a double tray arrangement, which allows for bottom watering—these include peas, beans and sunflower seeds. The remainder I grow in a flat without drainage, which does require more vigilance when it comes to watering, but which is much simpler when preparing and cleaning up.

Secondly, you will need to decide on a soil substrate to grow the crop in (although some growers have had success growing without soil). After much experimentation, I have settled on a mix that includes about 60% fine coir mix (a premium hydroponic mix has been by far the best), 20% sifted chicken manure compost or worm castings and 20% vermiculite. By including compost in the mix, it is not necessary to add nutrients when watering the crop. I try to mix up about 20 litres of this at a time.

Thirdly, you will need to get yourself some seeds. This part of my learning has been the trickiest. There are many suppliers of seeds that are specifically for sprouting or microgreens. Some of these suppliers however are very expensive. After trial and error, I have settled with one provider from whom I buy broccoli, kale and radish.

Fourthly, you will need a place to put your trays while they grow. Depending on how much room you have and how many trays you wish to grow concurrently, the most efficient method is to grow them vertically on wire shelves.

Lastly, it may be necessary to add some artificial lighting. Microgreens only need access to light during the final stage of the growing process, so even though you may have a large number of trays under seed, you only need enough light for a small proportion of them at any one time. I purchased compact fluorescent lights from a hydroponic supplier, and they fit very nicely on the shelving unit I use.

That’s about it for the essentials. Some other items which will make things easier are some jugs and strainers (to soak and drain the larger seeds), scales, a funnel and a small spice jar for spreading the smaller seeds. I also use a pressurised water pump to water the seeds while they are germinating and a larger jug to water the more advanced crops.

Sowing

When you grow peas, beans, sunflower or wheat the results tend to be better and quicker if the seeds are soaked in advance, generally for between 8–24 hours. If you are patient, you can soak and drain then keep the seeds moist until sprouting starts (up to 3 days) and then plant them. However, I don’t normally bother with this. Smaller seeds such as radish, broccoli and kale can be sown without soaking.

In all cases, the seeds should be sown into moist soil. If you are using a single tray without drainage, a measured amount of water should be used prior to adding the soil so that you achieve a consistent moisture level. When using a double tray, the soil can be given a good soaking and then be left to drain.

The seeds are then spread quite thickly over the soil surface. I then normally cover the seeds with a paper towel before wetting the seeds further with the water spray (the paper towel has proved the best way to prevent seeds from sticking to the tray above when they are ‘stacked’.

Stacking the trays

Except for perhaps faba beans and coriander, microgreen seeds do not need to be covered with additional soil after they are sown. However, the seeds do benefit from being ‘stacked’ or weighted down. The easiest way to do this is to place several trays on top of each other. Larger seeds benefit from greater weight being applied. The smaller seeds require less weight and for a shorter period.

With peas, beans and sunflower seeds the weight should be retained until the roots have started to penetrate to the bottom tray. Without the weight, the germination of these larger seeds tends to be much less consistent.

Keeping them in the dark

The concept of microgreens is that the seeds are grown in no or very low light for an unnaturally long period of time. Once they have reached approximately 75% of their harvest height, they can be exposed to light. The crop will then very rapidly green up and increase in height. Once the sprout starts to develop the first set of true leaves, it is ready for harvest. For the first few days, the seeds can be kept dark by stacking the trays. Once a tray is unstacked, it can be kept in darkness by placing an upside-down tray on top of it. Alternatively – as I have done – it can be covered by thick fabric. I cut up several old towels and sewed custom covers to slip over the trays. This allowed them to remain dark while also allowing some air circulation.

Crops

The first part of this article explored how I established my microgreen garden. In this second part, I will focus the different crops you can sow.

Growing sunflower seeds

The sunflower microgreen is crunchy and delicious and a very economical product. I use 120g of seed per tray and soak them prior to sowing. They are relatively slow to get started, but once they are about 6–7cm they can be uncovered and grow very quickly. You can produce 300–400gm of shoots per tray. However, while the rewards of this crop are great in both taste and volume, it is a very fiddly seed to harvest.

It is not unusual for the seed heads to stay connected to the sunflower sprout right up until harvest time. They then require painstaking removal to ensure that the crop is edible. I have found that the most effective method is to turn the whole tray upside down (supported) into a larger tub of water — soaking the seed heads and making them easier to remove. Often with a vigorous shake, most will fall off. Many a time I have considered giving up on growing sunflower seeds, but once the tray is successfully harvested, I inevitably consider the effort worth it.

Growing peas and beans

Pea and bean microgreens are a very economical way to produce a vegetable crop that is both quick and versatile.

Broccoli (left) and pea (right) microgreens ready for harvest

After trialling quite a few varieties, I now mainly grow blue peas. These I have managed to source at a local Indian grocery store by the kilo. Snow peas are also great but are much more expensive. Dunn peas can be sourced at stock feed outlets, and they also produce a good crop.

Peas require soaking prior to sowing, and they will expand to more than double their size so make allowances for this when adding them to a container. I use 220g of peas per tray, keeping them heavily weighted for the first 3–4 days, or until the roots have reached the bottom tray and the sprouts are almost 1cm high.

Faba beans are a great alternative to growing beans on the vine. They produce a prolific crop then is vigorous and easy to harvest. The sprouts are tender and taste just like a bean. I use 250g of faba beans per tray, which I pre-soak and — following sowing — cover with an additional layer of soil. I have found the faba beans that can be purchased in 1kg bags at Mediterranean delicatessens are very economical and have consistent sprouting.

Beans and peas can be harvested when they are around 10cm tall. By then, they will have multiple sets of leaves or tendrils, but they are still tender. Both are very easy to harvest and store well in the fridge. They are terrific cut up in salads and added to stir-fry or in an omelette.

Growing radish, broccoli and kale

Radish is probably my favourite microgreen. Not only are the seeds relatively cheap, they are a quick grow and the flavour is superb and unmistakably radish-like. I use 25g of seed per tray, which I decant into a spice jar and sprinkle evenly over the soil (no need to soak).

Broccoli and kale have very small seeds, so I only use 15g of seed per tray. These highly nutritious microgreens have a much more subtle flavour and are a much finer sprout.

With these seeds, the germination process is accompanied by what looks like mould. It is quite alarming the first time you see it. However, it is natural part of the germination process which we do not normally witness, as seeds sown to grown vegetable seedlings are planted under the ground. This fuzzy substance disappears (or is hidden from view) once the stalk of the microgreen starts to develop.

Sown at the densities described previously, these seeds produce consistent and prolific crops. While best eaten within a few days, I have kept them successfully for up to a week. I usually try to buy these three varieties from the same provider and I try to buy 200-300g of each per purchase, to reduce the cost of shipping.

My set-up

A microgreen setup can be as simple or sophisticated as you choose

After initially trialling a few trays of microgreens, I decided to invest in a decent set of shelves, ample trays and range of seeds. This allows me to have as many 10–12 trays in various stages of growth at any one time.

The upside of this is that I have a constant supply of fresh and nutritious greens. Often there is an oversupply, at which point my friends and family will get to share in the bounty. It also means that I get to spent time in my ‘garden’ every day, attending to the watering, covering and uncovering, inspecting, sowing and harvesting.

The downside is that it does require constant attention. To keep a crop of microgreens going from sowing to harvest means that they will need watering most days and rotating through the dark/light cycle. I stop sowing crops over a week prior to going on an extended holiday, and it takes up to 10 days to get my first harvest after I have been away.

The joy I get from growing microgreens has been a surprise. If you can imagine the reward of seeing a crop go from sowing to harvesting—a process that can take many months in the garden—every few weeks, then you can get a sense of the pleasure it can bring to the committed gardener.

If anyone is interested in dabbling in this addictive yet productive hobby, I am more than happy to share my knowledge with you.