You can use fertilizer when growing microgreens but it is recommended that you use safe microgreen fertilizer to ensure that your microgreen crop is as healthy as possible for your consumption.
Do not use plant fertilizer as that is not the best solution. Continue reading to learn more about various organic products that you can use to help your microgreen crop yield.
Before we dive in and learn about fertilizers for microgreens I wanted to share with you the product that I prefer and use for my own personal microgreen crops.
This is by far the best concentrated microgreen fertilizer you can buy. It is a bit pricy but the product is diluted and will last a very long time.
It is also easy to use. You mix the solution into a gallon of water and feed it when bottom watering your microgreens.
Microgreens are not full-grown plants. Rather, they are the first cotyledons that come out of the seed right after germination and are harvested in a period of one to two weeks. As such, some of the reasons why people may use fertilizers may not be as relevant in the case of microgreens.
That being said, and as we discuss below, there are definitely good reasons to use fertilizers in certain situations when growing microgreens. We must be careful, though, in balancing the value-added against the possible negative effects that could impact the health and taste of the microgreens. Being delicate, anomalies in taste will become more apparent – especially when eaten raw in salads or used as a garnish.
Let’s first see why fertilizers are used to grow plants.
Fertilizers are a source of nutrition that allows the plant to grow greener, tastier and taller, given that they can provide nutrition above and beyond what soils or growing media can provide without fertilizer. For understanding this further, let’s probe a very basic Nutrition 101 question.
When we think of growing microgreens, shoots, or fully-grown plants, the first thing we often picture is the soil bed the greens come out of. While accurate in many cases, this is misleading.
Plants grow through photosynthesis, a natural process involving the following chemical reaction:
6CO2 + 6H2O → C6H12O6 + 6O2
Take a close look at the equation above. On the left-hand side (the inputs) are six molecules of carbon dioxide with six molecules of water. We know that light is needed to trigger photosynthesis, but notice anything missing?
That’s right, there’s no need for soil per se to grow plants. The function of soil is to provide a medium that has the 13 essential nutrients (the Nitrogen-Phosphorus-Potassium or N-K-P combo being the biggest need) that add to the health, taste, and other attributes of the plant. The base also provides a place where the plant roots can anchor and draw water and other nutrients from below.
Bottom line – we don’t need soil to grow plants, certainly not ones that can germinate and get ready for harvesting as quickly as the average microgreen.
We do, however, need a base – which could be soil, a growing medium (like coco coir), water, and light. We can also deliver nutrients to the growing base using composts and/or fertilizers.
Composts and fertilizers are often used interchangeably by amateur gardeners, but they are not the same thing. Composts are decomposed organic material that adds to soil quality – the so-called “soil food web”. Fertilizers, while they may be applied to the soil at times, are specifically aimed at providing nutrition directly to the plant.
As we will see below, this distinction makes a difference when growing microgreens in particular, when the soil is not often reused and therefore does not need to be replenished and refreshed through composting or the use of gentler (organic) fertilizers.
For the rest of this discussion, we will not be talking about various types of composts (e.g., cow, sheep, or chicken manure, vermicompost, or what you can create out of decomposing your organic kitchen discards). Instead, we will be focused on fertilizers, specifically.
Fertilizers can be two types: (a) organic, or (b) inorganic or chemical.
The table below captures some differences produced by organic vs. inorganic fertilizers:
| Attribute | Organic | Inorganic/Chemical Fertilizer |
| Produced | Naturally, with minimal change in underlying ingredients. | Mixed and treated to produce desired nutrient balance synthetically. |
| Nutrient Value | Good, but content and release time could vary from batch to batch and is not predictable. Does contain micronutrients. | Precisely proportioned for a specific use, predictable in terms of main nutrients. Often lacks micronutrients. |
| Impact on Plant Growth | It will tend to make plants grow faster, be taller, and greener – however, effects will vary based on specific plant and type of organic fertilizer used. | Same as organic in the basic scenario but will tend to act faster due to a specific mix of nutrients being applied. |
| Impact on Soil | Gentle on the soil, support microbiological life in the soil. | Can be rough on the soil, especially when used in larger quantities and over several crop cycles. |
| Cost | Higher, both per unit and also due to higher amounts that may need to be bought | Lower, both per unit and in terms of being specific in the amount required. |
Growing microgreens is different than growing normal plants indoors and outdoors. Below are some of the adjustments in thinking you need to make when considering whether to use organic or chemical fertilizers to grow microgreens specifically.
All in all, both organic and synthetic fertilizers can be used, but their use must be targeted in terms of suitability (type of microgreen, taste factor) and controlled.
Growing microgreens can be effectively done in one of three media: (a) soil, (b) a different growing medium, and (c) water. We will discuss each of the options below.
When growing in soil, the need for fertilizers is diminished, though compost or fertilizer could be added in smaller quantities. Good, porous, organic soil mixes may well be sufficient. Many growers, however, prefer not using soil due to fear of mold, rot, and associated problems.
There has been a growing move towards using a soil-free medium such as coconut coir, hemp pads, Rockwool, burlap, or coco-fiber pads. These substantially reduce the fear of waterlogging or mold. However, you may well need to add some fertilizer, since the base does not naturally possess the key nutrients that soil would have.
Many microgreens can be sprouted hydroponically – simply in jars of water at home or with commercial operations with some soil but lots of water. In these cases, fertilizer use is again necessary since nutrients must be added to aid growth. This is important since there are certain microgreens such as alfalfa or kale sprouts that actually do better in water.
Hydroponically grown microgreens are less messy (little or no soil, no compost), can be controlled better, and yield great products when proper nutrients are added.
Microgreens grow fast, and some scoff at the idea of fertilizers, positing that the seed itself has enough nutrients to sustain the early germination and harvesting of sprouts. However, the results are clear – with strategic use of fertilizers, you get better taste, a greener color, and a bigger crop (that is, higher yield).
If you have large seeds, you may want to reduce the amount of fertilizer when growing in soil-less mediums or in water. But even so, it does help unless you overdo it.
We first discuss the fertilizers that work best, specifying the type of use where relevant. We use suggestions from industry experts such as True Leaf Market:
Purchase Azomite Trace Mineral Here
Here are some organic fertilizers that do not work as well with microgreens (reasons listed):
Below are three inorganic fertilizers that can be used. The first two, Miracle-Gro and FloraGro are recommended by True Leaf Market:
Purchase FloraGrow Nutrient Here
Without getting into specific details, think back to the fact that chemical fertilizers tend to make the plant grow too fast and can oversupply nutrients. Certain types are not suited to certain microgreens, but more importantly, the user should be controlled to avoid burning the product.
Adding the right types of fertilizers, in controlled amounts, to hydroponic and non-soil-based growth mediums can produce dramatic effects on your microgreen crop in terms of both quality and quantity.
The main goal is to use in the properly specified amount and get comfortable with the results. The end product is sure to be delicious!
