By Jody Wall, NSCF Site Co-ordinator.
In recent years microgreens have moved from the fancy plates of high-end restaurants to the garages and greenhouses of gardeners around the world. These little greens have made their way into the hearts, and into the regular diets, of millions of people. They are versatile and relatively easy to grow. With a quick turnaround time and small space requirement, they have become a go to crop for small market growers everywhere. I started growing microgreens to supplement my market garden income. It proved such a great business I made the business decision to cease the market garden and concentrate on just microgreens. Such is their economic potential. However, most people should be able to grow microgreens at home with few problems. With a small amount of practice and patience, the correct seed choice and irrigation techniques, you will be on your way to enjoying fresh home grown greens.
Setting up for growing microgreens
To start with, you need space, somewhere protected from swings in temperature, especially to the hot side. Also, it should be somewhere that you will visit every day. In Permaculture terms, microgreens are a zone 1 type crop. Many people use a garage, or if you have a large enough laundry you can use it. I use my existing Titan Shed. It is uninsulated, and I live in Queensland, so temperature control is a real issue. Gumtree is a great place to find cheap, second-hand, metal shelving to hold the seed trays.
You will need space for twice your estimated the weekly consumption. One area for this week’s crop, one area for those you are growing for next week. Most microgreens will give you a second shoot if you leave them in the soil. This also works to keep them fresher longer. With practise you will learn which varieties grow too much during the second week, and need to be cut at the right time. Leaving some varieties lets them get lanky, and stringy. My lovely partner’s favourite are snow pea shoots. These are a hardy, quick growing type. They come in a few varieties, but all tasted pretty similar to me.
As part of your setup, especially consider ventilation in the space. If it has anything less than a reasonably constant airflow, I would strongly recommend installing pedestal fans to push air across your sprouted microgreens. The density of growth makes microgreens particularly susceptible to stem rot, an evil fungus that will destroy trays of microgreens in a few hours. Maintaining airflow is an almost foolproof method of avoiding this issue. Pedestal fans are cheap and use minimal electricity. So they are a very efficient method of ventilating your growing area. Of course, there is the option of an insulated and climate-controlled room, but that is more in the advanced microgreens production field.
After you have set up the growing space you will need trays. I have found the standard nursery seedling trays work best. Around 200mm x 300mm is best as any larger and the tray becomes too large to handle, and the microgreens too difficult to cut. I would start with four trays: two for this week and two for next week. Wash the trays the same as you would for new seedlings.
Most green vegetable seed can be used to produce microgreens. Also popular are alfalfa, amaranth, beetroot, chinese cabbage,cress, dill, barleygass and oatgrass, peas, radish and sunflower.
This is the the fun part. It is a fairly simple process and will be familiar to those that have grown seedlings before.
- Fill the trays using a seed raising mix, or a finely sieved potting mix. Some of the trays have a mesh patterned bottom to allow water drainage. I lay down a sheet of chux to keep the potting mix from falling through. You can also buy riggy didge microgreen trays. In my experience, they are expensive, and unnecessary. I use solid floor trays as well, just remember to drill holes in their bases to allow water to drain.
- Many microgreens seeds are pinhead size. Using too coarse a potting mix causes the seed to fall into areas of the mix that do not allow them to grow. This is a waste of seed, and of the area in your tray. I use a combination of worm farm tailings and a cheap seedling mix. The important thing to remember is that the seeds will not be drawing on any nutrients in the soil. They will only live long enough to use the nutrient that comes packaged in the seed itself. I use worm tailings because my next use of the growing medium is to fertilise my second-year trees that I transplanted. This is an important consideration. You do not really get to reuse the growing medium, the soil. It will be matted with root structure from cut microgreens. It is far too time consuming to remove all the roots in it. Either compost the soil or reuse it on a larger plant that will not be bothered by the decomposing roots.
- Scrape any excess soil off, then tamp down the soil in the trays until it is firm but not compacted.
- Pre-water the soil before placing seeds in the trays. I sit my trays in water for 5 mins before seeding. If the trays have good drainage, this will help to ensure an even watering across the tray. As I will discuss later, this is also the method I use to water my microgreens with daily.
- Sprinkle seeds liberally over the surface of the seedling mix. Remember the point is to have dense, compact growth. This goes against the instincts of a seedling grower, but it produces the results you want. I use a tablespoon. I have found my hands just do not do the same job. Just imagine you are sprinkling sugar on your breakfast cereal. The seed should be a single layer thick, with seeds almost touching.
- Softly moisten the seeds. I use a new pump poison sprayer, or a small spray bottle also works. Obviously new or very, very clean.
- Cover the seeds with a light sprinkle of soil. Or for many of the bigger seeds, I use boards cut to the size of the tray. These have the advantage of ensuring darkness, keeping vermin off, and trapping a small amount of moisture.
- Important. I know it’s difficult. It’s new life. It’s a new project. You will do this every week. So, enjoy the anticipation.
- After a couple of days, literally, the boards will start to rise up as the mass of seedlings pushes against them. Now is the time to uncover the trays.
- Mist water the seedlings, or use an ebb and flow irrigation technique. The real danger for microgreens is root stem fungus infection. They can be perfect one day but dead the next morning. To combat this, you will need constant airflow . Easy to do with a pedestal fan rotating over the trays, and irrigating from the soil up, rather than constantly wetting the leaves and stems with overhead watering.
- To harvest your microgreens, trim off desired quantity using a very sharp long blade. Grasp the microgreens firmly around the stems and cut as close to the soil as possible. Try to avoid scissors, as the crossing of the blades bruises the stems, and starts the plant rotting immediately. I keep them in the fridge. I’ve found they stay fresh for up to a week.