As an avid microgreen grower, I want to reassure you that microgreens are perfectly safe to eat just like any other vegetable, if prepared properly. You should not need to water your greens before eating them unless you have sprayed them with nasty chemicals.
All of our microgreen seeds are regulated by DEFRA to ensure that they are entirely safe to eat. This is something to keep an eye out for if you buy from elsewhere as not everywhere has the correct certification.
A common concern of new growers is that they have mould growing on their microgreens - before you start to worry, consider whether this might instead be root fur. Root fur is perfectly normal and is how the plant absorbs the water so do not worry.
If you think you have mould on your microgreens check this out: mould fungi looks like a long stringy spiderweb creeping across the surface of the soil. There are several ways you can combat mould. The most effective is with 3 - 6% Hydrogen Peroxide (H2O2) solution . This can be purchased from most pharmacies and is a standard anti-mould remedy for Microgreens. Fill a bottle with a few mL of H2O2 and top up with water to spray them. You only need a small amount of solution. Be careful not to get the concentrated H2O2 on your hands. Shake to mix and spray on the affected area daily until you don't see any more mould growing. Usually one of two applications is all you need. Hydrogen peroxide is used on wounds as an antiseptic and an anti bacterial. It is also a bleaching agent so don’t get it on your hair or clothes. It is considered suitable for organic gardening as it breaks down very quickly. It can be corrosive when concentrated so be extra careful with your skin and eyes and especially around young children. Store it in a dark location as it degrades when exposed to light. If you have used it then rinse your harvested Microgreens well before eating them. Do not use it on plants that have been exposed to light as it can burn their leaves. Mould will usually die off when exposed to light and when there is lot of air flow. If your greens are nearly ready for light, just uncover them. Place them beside an open sunny window and the mould will die off quickly as the microgreen leaf surfaces dry out. An alternative to hydrogen peroxide is a teaspoon of baking powder mixed with water in your spray bottle. Vinegar or lemon juice, mixed 50/50 with water and then sprayed on the affected area, can be effective as well.