One of the most common questions I get asked is on watering - when to water, how to water, how much to water. My response to that is almost always, "it depends". I say that because these questions don't come with enough information for me to provide an informed answer.
To understand how much water to give your microgreens, you first need to know the medium you are using to grow them. Different mediums may have different reactions to water and water retention capabilities. Also the particles in the medium come in different grades which will impact the amount of water it retains. In addition, how you water also depends on what stage of growth your microgreens are in. So you see, it's not an easy question to answer.
Below are some useful tips on how to water your microgreens based on 2 grow mediums - soiless potting mix (coco peat) and hemp mat (hydroponics).
Watering on Mediums
1. Soiless Potting Mix - Coco peat + perlite
Coco peat is a by product of the coconut's husk and contains natural nutrients. It's low density and good water retention is ideal for growing microgreens.
One of the main indicators of knowing how much water is in your potting mix is by feel. By that, I mean, literally picking up your tray and feeling its weight. This way, you know how heavy your tray is originally, when you sow your seeds, when you water it for germination and so on and so forth. The weight of your tray will tell you if you need to give it additional water.
Do this exercise:
a. Lift an empty tray/pot which you are using to grow your microgreens and feel it's weight.
b. Now add your potting mix (unwatered) into the tray and feel it's weight.
c. Spray/water the tray of potting mix until water starts to drip from the holes at the bottom. Now feel its weight.
What you are doing is understanding the weight of your tray when it's dry and completely soaked. This will tell you if your tray has enough water during your growing process.
2. Hydroponics Medium
This is much simpler because with a hemp, felt, or coco mat medium (just some mediums used in hydroponics growing), you can see if your medium is wet. With the hydroponics method, your medium must always be moist to wet. If it is dry, your seeds will not germinate and if your microgreens have germinated and are at the cotyledon stage, then the microgreens will wilt on a dry mat.
How To Water Your Microgreens
How you water your microgreens really depends on the stage of it's growth.
When you first open your microgreens to light (when they have germinated), a light spray on the medium is always recommended because the stems and cotyledon are still immature.
As they start to grow taller, and you notice roots growing from the bottom of your tray, it is a good idea to water them from the bottom (known as bottom watering). This is especially useful for seeds like peas, sunflowers, and wheatgrass which root aggressively and grow out of the tray. Bottom watering once a day is usually sufficient.
The method for bottom watering is simple. If you are using our current microgreens germination tray set, simply remove the 10 punnets from the bottom tray. Spray a generous amount of water onto the bottom tray and place the punnets back in. If you are using a home recycled container, then use a bowl or tray as a base and create a shallow pool of water. Let the soil soak up the water from below.
Another method of watering in the mid-stage growth of microgreens is side watering. In this technique, you water the microgreens from the side of the tray into the medium. This ensures your medium is watered properly.
When you are about to harvest your microgreens, make sure you let the microgreens sit without water at least 6-8 hours before harvesting. This is so there is less moisture in your microgreens, making it easier to dry and store.
Like watering any plant, it is important to not over water your microgreens. Always lift your tray to feel its weight. A heavy tray means your medium has retained water and you should avoid watering your microgreens further.
Like everything else, practice makes perfect!