Growing microgreens without soil is becoming more common.
I’m sure you’ve seen photos on Instagram of beautiful microgreens growing on thin fiber pads.
These pads can be made of wood fibers, jute fibers, felt-like materials, or coco coir fibers.
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Above are three of the most popular microgreen growing pads. Click each image to get more information.
Growing Microgreens Without Soil
Let’s face it, working with soil inside your home can make a mess. Soil has also been blamed for bacterial and fungal issues on microgreens. Fiber pads may remove the need to wash your microgreens before consumption.
But that doesn’t necessarily mean growing microgreens in soil is a bad idea. Soil also has many advantages.
Especially for those of us that have busy schedules and are prone to forgetting to water our plants. The volume of soil retains more water than the thin fiber pads regardless of what their marketing propaganda suggests.
Soil also provides nutrients for the young microgreen seedlings. Yes, the cotyledons in seeds do contain a lot of energy, but as the microgreens grow in trays, they require additional nutrients provided by a good professional soil mix.
I’m using the term soil even when the growing medium might be considered soil-less as in coco coir potting mixes. It’s just easier to say soil than potting or starting mixes.
Time & Space is Money for Indoor Gardeners
As an indoor gardener, I have limited space, time, and money to grow nutritious vegetables and greens.
As such, I’m always looking for a better way to grow vegetables and greens. Whether it be cleanliness, efficiency, or cost. But ultimately, the more productive method is the one that I’ll choose over the others.
Growing Microgreens Without Soil - A Test
Fiber microgreen growing pads would be ideal for me.
Storing soil takes up space. I only have so much storage place in my house. Besides, the soil bags are heavy, and I need to drive to a hydroponic specialty store to pick up a bag. While fiber pads are delivered to the house.
Soil can also make a mess, both when starting microgreen seeds and during harvest.
There’s a belief, whether true or not, that soil can cause fungal disease and bacterial problems such as E. coli on the harvested greens. Therefore, some regulatory agencies require microgreens grown in soil to be washed before selling them.
Furthermore, I’m selling media for growing microgreens, and shipping soil is many times more costly than it would be to mail a thin fiber pad.
That said, I’m still not giving up time or productivity to grow mine or my customers’ microgreens over a bit of mess or the cost of shipping. Quality and quantity is more important to those of us with limited space and time.
So, the best way to see if growing microgreens on a fiber pad or on soil is better is to design a microgreen growing test and compare the rate of growth and harvestable yield.
Below is such a test.
Microgreens Grown In Soil
We use to regularly use FoxFarm Bush Doctor® Coco Loco® potting mix to grow microgreens.
Besides coco coir, Coco Loco contains aged forest products, perlite, earthworm castings, bat guano, kelp meal, oyster shell, dolomitic lime, and well as beneficial mycorrhizal fungi.
However, we now mix our own potting mix. We call it simply Home Microgreens Potting Mix. You can purchase it from the Home Microgreens Store.
Microgreens Grown on Jute Fiber Pad
I cut GreenEase Jute Micro-seed pads to fit into the same size container used for soil.
The micro-seed pad is made of jute.
Jute is described as a natural fiber designed to effectively control water, allowing seeds to thrive in a variety of hydroponic systems.
I tested two watering methods using the jute fiber pad, a shallow tray where water would stay and be absorbed, and a deeper tray that could be watered from below similar to the soil tray.
Microgreen Grown in Soil vs. Fiber Pad
The surface area of all three trays is the same.
The same weight of Tatsoi seed is applied to the surface of the soil and jute fiber pads.
Both the soil and jute fiber pads are pre-wetted with a spray bottle and also sprayed after planting.
All three seed trays are placed on a Vivosun Seed Heating Mat with covers over them.
Photos of the Microgreen Jute vs. Soil Test
Pictures tell the store. Below are side-by-side comparisons of the microgreen growth over nine days.
Click to expand images if you're viewing the post on a computer.
Day 0 - Seeding
Day 3 - Sprouted Microgreens
Three days after seeding the trays there isn't much difference between the trays. The germination rate is a bit lower on the shallow tray.
Day 5 - Seedling Microgreens
As you can see, the microgreens grown in soil are starting to grow quickly; they're denser, and the leaves are larger overall.
While the microgreens in the more protected deep tray are growing better than those in the shallow tray. The unprotected tray dries out quicker and has more exposure and is more vulnerable.
The microgreens grown in soil have a more stable environment, more consistent moisture and temperature, as well as, more room for the roots to anchor the plant.
Regardless of what others say, nutrients in the soil are having an effect on growth.
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Day 7 - Harvestable Microgreens Grown In Soil
It's obvious that the microgreens grown in the potting soil mix are growing quicker and better than either of those grown on the jute pad.
If you have any doubts take a look at the photo below that was snapped on the ninth day after sowing the seed.
Is It a Good Idea to Grow Microgreens Without Soil?
No, it's not a good idea.
Growing microgreens without soil may be cleaner, and a bit less of a hassle, but in the end, the microgreens don't grow as quickly. The yield is also much lower.
For the Home Microgreen Gardener growing microgreens on fiber pads, will cost you time (because it takes longer to grow on a grow mat) and the tray will produce less nutritious greens.
Is This Test Scientific?
Look at it this way, growing microgreens at home isn't scientific either.
We pay as much attention to our plants as we can. But there are times when life gets in the way.
I didn't ignore any of the trays during the nine days. But I also didn't cater to them every hour.
Microgreen seeds grown in soil grow faster compared to those on jute fiber pads.
Will results vary? Most likely to some degree they will. I've seen many photos of beautiful microgreens grown on fiber pads.
The question is how were they grown? Did they have a constant supply of fresh water, and were they grown in a protected environment?
For the home microgreen grower, it's best to use a premium potting mix. You'll see quicker results and not have to tend to them as frequently.
Our Articles Testing Microgreen Growing Media
Our Position on Growing Microgreens Using a Grow Pad or Hydroponic System.
We want you to grow microgreens anyway you want.
As you can tell by the article's tone, we are a fan of growing microgreens on the soil.
We use a mix composed of coconut coir and peat moss. However, we believe you can grow the best microgreens using a potting mix growth medium.
However, we understand that soil isn't the best for everyone or in every situation. But there are some myths about using soil that we would like to address here.
First thing, people think that using grow mats causes less mess. However, if you have ever worked with hemp grow mats, you know they are messy too.
We fill many a growing tray of microgreens each week with little mess. So we have written an article on how to store and not make a mess with soil.
Second, for the best results with grow mats, you need to a nutrient solution to fertilize the plants.
Because it is another misconception that microgreen seeds contain all the energy they need to succeed, they may grow, but to get better results, they will need essential nutrients.
Especially if you are growing your plants to the first set of true leaves or baby greens.
It seems hydroponic microgreens are becoming more popular.
But, unfortunately, I don't get it.
Hydroponic vertical gardens make sense in urban settings. Where space is expensive, or you are growing many microgreens or baby plants such as lettuce. This is an excellent place to grow by the hydroponic method.
But the hydroponic method is a lot of work to grow your own microgreens at home.
There are many extra things you need to buy in order to grow hydroponically.
The fertilizers or nutrient solutions you need to use require pure or distilled water. Tap water generally has too much buffer or impurities that raises the pH of the water.
The pH of water is critical to growing hydroponically. Therefore, the pH level needs to be on the acid side of neutral.
This means you will also purchase a pH testing kit, pH down, which is a phosphoric acid to lower the pH.
The pH range needs to be between 5 and 6 for the best uptake of artificial nutrient solution. This is because the microgreen roots uptake nutrients differently in a liquid than in soil.
It's also true that you will need to add nutrients if you are using pure coconut fiber.
Coco coir and peat moss are nutrient-poor.
However, a prepared growing medium such as Home Microgreens Potting Mix has natural nutrients, and there is no need to add fertilizer or use a pH kit.
We have also heard that you need stronger light using hydroponic methods. This means you may need to use more expensive grow lights rather than less expensive LED shop lights.
Lastly, not all microgreens grow well on grow mats. So the type of microgreens you grow will be limited.
Disadvantages of Using Soil
I make it seem like growing microgreens on soil is perfect. Nothing is perfect.
Soil is heavy, and it takes up space. It is also harder to recycle than natural fiber grow mats. But I will say there are more ways to reuse soil than any grow mat.
Soil can add to possible mold issues to microgreens. Soil can hold and carry mold spores than using water.
But in the end, we want to grow microgreens for health benefits. We think that microgreens grow better on soil.
If you saw all the extra work we have to do to use and sell our potting mix, I think you would be surprised how much space it takes up, how many times we handle the soil, and how much extra we pay to ship out soil to our customers.
These reasons are probably why online retailers don't sell potting mixes.
However, we think the benefits of using soil are worth the extra work, lifting, mixing, and shipping cost, or we wouldn't do it.
We have tested many soils and grow mats. Below are links to those articles. See for yourself which grows microgreens the best.
Our Articles Testing Microgreen Growing Media
That is what we want for us and you, the best possible microgreens.
Frequently Asked Questions
In this article revision, we decided to answer some of the most frequently asked questions we get on growing microgreens without soil.
Q: We don't want to deal with messy soil, so what is the best growing pad to use?
A: First, we don't think soil is messy. But if we had to use a growing pad, we think the coco fiber pads are the best. The easiest to use is probably hemp mats.
Q: What varieties of microgreens can be grown on hemp mats?
A: Well, we don't have a list. We need to create a list. But many different types of microgreens, such as basil and arugula, do not grow well on grow mats.
Q: I'm big on hydroponic gardening. Can microgreens be grown using the Kratky Method?
A: Not well with the exact Kratky Method, but you can modify it to grow some microgreens. We will also be working on creating articles using similar methods.
Q: Can I use my Home Microgreens microgreen kit with grow mats?
A: Yes, you can. Place the grow mat in the tray with drainage holes. Place a spacer(s) in the watering tray, so you can add water to keep the water level right at the bottom of the tray with the grow mat. Microgreen roots will grow down and bring water up to the mat, which will also wick up water.
Q: Is there a significant difference in nutritional value between microgreens grown in soil and on grow mats?
A: We are not sure how to test this. I guess it would also depend on what soil and nutrient solution you use to water the microgreens.
Have a Question?
If you have any questions about the information in this post or microgreens in general?
Please leave a comment below or reach out to me using the Ask a Question page.
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