THAMES

- Amaranth and basil microgreens for summer salads.

Over the years, after trialling dozens of varieties, we have come to settle on growing those that offer great eating qualities while being very prolific. In microgreens terms, it means that they are fast-growing and produce a large volume per tray. Since microgreens are relatively energy-intensive crops to grow, this logic led us to focus on growing mainly radish varieties, peas and sunflower microgreens, which we grow to be relatively “bulky” microgreens, rather than the delicate sort. We enjoy these greens every week of the year, and occasionally we grow a special tray of our favourite garnish microgreens, amaranth and basil.

Several amaranth varieties can be grown as microgreens; each produce slightly different results. The highlight of growing amaranth as microgreens is the intense magenta colour that can be used to garnish dishes. The vibrant hue makes any dish it is added to more appetising and enticing.

In contrast to its visual impact, amaranth microgreens have an average flavour though. It doesn’t add or subtract from the dish, so make sure the dish is tasty on its own.

On the other hand, basil microgreens are full of flavour and aroma. The flavour is similar to what you would expect from a full-grown basil leaf, and you can use any basil variety you have at hand. Organic ‘Genovese’ is my first which. It produces lovely tender microgreens. An alternative is ‘Opal’, which has dark purple leaves and stems. ‘Opal’ is more cold tolerant and, compared to ‘Genovese’, grows better in spring and autumn.

You can repurpose food containers or use any of your seedling trays or pots to grow microgreens. The growing medium is more important to get right.

Growing medium for microgreens should have a good water-holding capacity, drain well, be free of contaminants (toxins or disease), and be able to provide nutrients for your plants. It is best if the mix is free of weed seeds, but it doesn’t have to be. Texture should be small with no chunks, but I have had success with a relatively chunky potting mix. The depth of the growing medium can be as little as 1cm, but having 2-4 cm of depth will give you more time between waterings. Microgreens do need some nutrients from the growing medium, but not much.

I have successfully used various mediums, from our own soil (with and without compost, sand and pumice) to a commercial organic potting mix, seed-raising mix or just pure compost. While peas and radishes are tolerant of various growing medium and pH levels, amaranth, and even more so basil, will need a well-balanced mix to grow well – or they will stop growing after sprouting. Generally, what grows good seedlings will grow good microgreens.

On a tray of about 300mm x 300mm, I would expect to sow 3-5ml of amaranth seeds and 9-14ml of basil seeds. I aim for a density that will give me 5-7cm long stems.

Whenever I purchase new seeds, even from the same supplier, I need to retest and sometimes adjust the sowing density, as often the seeds coming from different batches are not exactly the same.

It is best to use fresh seeds, as germination rate drops over time. Old seeds with low germination rates will often rot in the tray. Even if you compensate, by sowing extra, the ungerminated seeds might contaminate the tray with mould and significantly decrease your yield.

Keep the trays moist throughout the growing time. Even just a day or two without adequate moisture will result in failure. To keep the seeds moist, lightly cover the seeds with a layer of growing medium, cover with shade cloth or newspaper, or stack your newly sown trays on top of each other (if they have flat bottoms). If you cover or stack the trays, open up the trays when the shoots emerge. A common mistake is to uncover trays while the seeds are still germinating and don’t have a solid root in the growing medium. This leads to the sprouts either drying out or sticking to the cover and becoming uprooted.

Depending on temperatures, amaranth and basil will take 14-24 days to reach peak harvest size. You can start harvesting from the tray gradually at any stage or wait for the preferred size and harvest all at once. With peas or radish, I expect to harvest at least 300g per 300mm x 300mm tray, within 7-10 days. With basil and amaranth, I expect half as much – about 100-150g per tray.

Once a tray has been harvested, tip the growing medium as compost around your garden or add them to a compost pile for later use for propagation.

Many veges, greens and herb varieties can be grown as microgreens. Experiment and try new ways of enjoying your favourite plants. Some other specialty microgreens that we have grown and enjoyed include chervil, beets (yellow and red colours) and sorrel. Try them out for colour and flavour this summer.