How to Grow Microgreens Indoors in Trays
You can grow microgreens regardless of where you live as you can grow them indoors without depending on climatic conditions because you control the growing conditions like light, temperature and wind. Most seeds germinate at room temperature, and that is why microgreens are one of the best nutritious products that can ensure food security for the remotest of countries with the harsh desert and droughts.
What you need to grow Microgreens at home
- Temperature: 20 to 22 degrees celsius (68 to 71°F)
- Container : 10x20 Seed Tray x 3 (one with holes, 2 without holes)
- A brick
Brick or any kind of weight to keep on the seed tray until germination.
- Growing Media: Coco-coir, peat moss, fine soil or grow mats
- Light: T8 LED grow lights, T5/T8 shop lights or a sunny window
- Spray bottle
Microgreens are grown in loose soil and need natural sunlight or artificial grow light with low humidity and good air circulation.
You can use coco-coir or a standard potting mix that has fine particles. The larger the particles, it gets more difficult for the roots to grow around. You can also grow microgreens hydroponically (slower growth).
Steps to Grow Microgreens at Home
Soak the seeds overnight
Only if you are growing chard, beet, sunflower, and pea seeds
Add the growing media to the seed tray with holes
The growing media could be a fine potting soil, coco coir or coco-coir/hemp grow mats.
Wet the growing media with water
Spray the seeds as evenly as possible
Mist some water to just wet the seeds
Stack another seed tray at the bottom
This seed tray will be without drainage holes because it will be used for bottom watering.
Stack another seed tray on top
The seed tray is usually covered for 3 to 5 days with another tray of the same size stacked on top to create a dark environment for the seeds to germinate and grow tall while searching for light.
Most seeds don’t require light to germinate, so keep them away from light for the next 4 to 5 days (black out phase). Once the seeds germinate, they try to look for light. When it is dark, they grow longer stems thinking they might get some light. The blackout phase gives us good sized microgreens of about 3-4 cm.
Place a concrete brick on the seed tray
This is done to have a good seed to soil contact and force the seed to push the roots deeper making the plant stronger. Some crops like amaranth have a very delicate root system and do not require that extra weight.
Seeds sprout, remove the weight
Wait for 4-5 days to see the weighted tray rise up as the seeds germinate. The sprouts will look yellow as it didn't get enough light to photosynthesise during the black out time. At this point, you can either introduce the microgreens to light which will make them start to photosynthesize and turn green, or put them under blackout for more days if you want them to be a bit more taller.
If the seeds have already germinated and are 1-2 inches tall, flip the top tray and cover it like a dome to avoid damaging the microgreens. This is called the dome method.
Water with a spray as required
Keep near a sunny window or under a grow light. Once the seeds germinate, they will grow roots that will pass through the drainage holes. Now you can start bottom watering, to avoid mold and overwatering issues.
There is no set schedule for watering. Just lift the tray and feel the weight. If it's light, it's time to water. Use clean water with a pH of 6.
Harvest just above the soil line.
Do not consume the roots.
Light Requirements for growing Microgreens at home
In general, plants need a full spectrum (400-700nm) bright light (1600 to 2000 lumens) and a color temperature of 4000K to 6500K. The recommended artificial light for growing plants are any T5 or T8 fluorescent lights, T8 LEDs or LED grow panels.
As a general rule, keep the lights on for 12 hours so the microgreens get 12 hours of darkness, sort of mimicking daylight. You can increase the light to 16 hours on, 8 hours off and test if plants like it.
How to Water Microgreens at Home
Lift the seed trays to get a sense of how much water the soil is holding. If it feels light, give your microgreens some water and make sure they are well hydrated. You will be growing thousands of microgreens seeds and they are going to suck up that water to photosynthesise especially when they are getting a lot of light.
Tips for preventing diseases in Microgreens
- Use sterile containers, organic seeds and seedling mix. Single use mats are the most safe.
- Avoid excessive seed density, low light intensity, low air circulation and follow GAP (good agricultural practices and GMP (good manufacturing practices).
- Buy seeds from a reputable company and use fresh soil that is free from harmful bacteria and/or fungi.
- Avoid root rot ( Pythium and Phytophthora) by making sure your media is not soaking wet and is drained well. Make sure there is not too much water or humidity.
- If your seedlings are not germinating, or the first leaves are brown or limp, or you see fluffy white cobweb growth, your seedlings are infected. Also inspect your growing leaves for mildew before consuming microgreens
- Radish, watercress, Swiss chard, and Thai basil microgreens are very susceptible to disease so you may plan to avoid growing them when you are just starting out.
- Harvest above the root line.
- Wash the microgreens before eating.
- Store the microgreens in the fridge in a ventilated container.
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