Microgreen Grow Mats Verse Soil: Which is Better, Hemp, Bamboo, or Soil?

This article and video embedded below shows how well two microgreen grow mats grow microgreens compared to our best soil.

The first of the microgreen grow mats is made from hemp. We have shown that this hemp grow mat will perform reasonably well when watered with an organic liquid fertilizer. 

The second grow mat is made from bamboo fibers. We have not worked with this type or brand of microgreen grow mat before, and we hope it performs well. 

The soil is Home Microgreens Potting Mix. This potting mix has outperformed all of the professional grower mixes and potting mixes sold in garden centers we have tested so far. 

Why We Are Testing Microgreen Grow Mats

There are several reasons we are testing grow mats.

• We are curious about which type of grow mat performs the best.
• People don't want to deal with soil; they want an alternative.
• Grow mats will reduce the weight of the package and cost less to ship.
• Storing grow mats takes up much less space than pallets of soil.
• I'm old and don't want to move 1,000 bags of soil a year.

However, any microgreen grow mat we sell will have to grow microgreens as well or better than the best potting mix.

There lies the problem. 

Microgreen Grow Mats in the Test

Terrafibre Hemp Mat®

Here's what the TerraFibre website says about their product. Spelling changed to U.S English version. My thoughts are in parentheses.

• Strong fibers to support rooting (agree).
• High water holding capacity, can hold 1050% weight in water (does hold water not sure about the %).
• Promote sustainable growing practices (maybe renewable).
• It is fully biodegradable and compostable (yes, but it takes a long time - see the image in the video).
• Cleaner to use than soil or coco (I would disagree - discussion below).
• Made from natural, sustainable fibers (natural yes, renewable yes, sustainable no).
• Promotes high germination rate (seems to germinate seeds well).
• Sustainable alternative to rockwool, peat moss, or coconut (yes, I'd agree).

My thoughts are that companies get carried away with the word sustainable. 

Merrian-Webster says this of the word sustainable:

of, relating to, or being a method of harvesting or using a resource so that the resource is not depleted or permanently damaged.

Hemp is an annual plant and needs to be replanted every year. So in a way, they're using something that would only decompose in the field. So I'll give them that, but fuel and fertilizer are still needed to grow a field of hemp.

Not so with bamboo or coconut fiber. They will continue to grow after harvest. We are harvesting peat moss faster than it is forming, regardless of what the Canadian Sphagnum Peat Moss Association says.

Hemp Microgreen Grow Mats Make a Mess

There is no way anyone can put a hemp grow mat in a tray without hemp fibers flying all over the place. Soil, if handled properly is so much cleaner than hemp grow mats.

Hands down, so I completely disagree with Terrafibre's statement that it is cleaner than soil or coco.

VegBed Bamboo Microgreen Grow Mats

Here's what the VegBed website says about their product. My thoughts are in parentheses.

Outstanding water retention holds 9.5 times its weight in water (seems to hold water well).

Eco-friendy (generic statement).

Naturally biodegradable (we shall see, but I don't see bamboo rotting very fast).

Incredibly easy to use (yes, except for the slight depressions that hold seeds).

Leaves no mess or residue - easy clean up (yes, for sure).

No nutrient solution or pH adjustment is needed (Well, we will see, but I think it will require fertilizer to keep up with soil).

It won't alter microgreen taste like other mediums, e.g., hemp (I didn't know hemp alters microgreen taste, but it may?).

Made in the USA (made into mats in the States or grown? I'll email them and update).

Bamboo Microgreen Grow Mats Are Clean

I will give them mats the cleanliness star. They are easy to put into the trays and come out easy leaving no mess behind. You can cut them and not make a mess. 

I enjoy that about this product.

Question is can they grow microgreens. After all, that's what we are trying to do.

Microgreen Grow Mats Test Video

Below is the video of the process we took to test how well hemp and bamboo microgreen grow mats perform compared to the Home Microgreens soil. 

As I plant, water, and manage the test, I talk about my observations during the process. 

Summary of the Microgreen Grow Mat Test

Equal amounts of seed are placed on (from left to right) Terrafibre® hemp grow mat, two VegBed bamboo grow mats, and a Home Microgreen potting mix tray.

There are two trays for the bamboo fiber. One will be watered with tap water and the other with Ocean Solution fertilizer.  We have already shown that the hemp grow mats need fertilizer to grow microgreens, similar to the potting mix (Part 1 and Part 2).

Planted Microgreen Grow Mats

It was easy to plant the mats, but due to their fluffy texture, we found it hard to level the surface of either grow mat. Because of this, the seeds have a tendency to roll into the depressions on the mats.

Grow Mats in the Blackout Period

We covered all trays for 3-days to allow the seeds to germinate. The weight gives a better seed to media contact. A couple of tea towels are also placed over the trays to exclude light. 

Placing the Microgreen Trays Under the Light

On day 3, the microgreens were removed from the blackout and placed under lights. Note: the lights do not look that purple to the eye. That is an effect of the camera. However, the image was darkened, so the microgreens showed better in the photo.

At this time, the microgreens were also bottom watered. The two left trays (hemp and bamboo) were watered with an Ocean Solution of 1-oz to a gallon of water. Regular tap water was added to the watering trays of those to the right. (bamboo and HM soil) 

The three left trays are up on lids to bring the plants closer to the light. A bit higher than the soil tray, but closer to the same height.

A commenter on the hemp mat article mentioned the lower position of the hemp tray might affect the final results. I want to eliminate that variable from this test. 

After 5-days Under the Lights

I forgot to mention that the lights are Barrina 24-watt LED grow lights. There are two light bars on the shelf. 

The Purple Vienna Kohlrabi microgreens grown in the Home Microgreens Potting Mix are for sure taller. The leaves are much bigger than both grown on the hemp mat (far left) and the two grown on bamboo mats. 

In fact, the ones grown on the bamboo have some yellowish-brown leaves.

Day 10 - Final Results

The microgreens were removed from the trays and set at the same height to better view the results.

As you can see, the Kohlrabi microgreens grown in the Home Microgreens Potting Mix (far right) are much taller, wider, and the leaves are bigger than any of the other grow media. 

The second-largest is the microgreens grown on the TerraFibre® hemp grow mat (far left) watered with Ocean Solution organic fertilizer. 

Of the two VegBed bamboo grow mats (middle two), the one watered with Ocean Solution (leftmost) is a bit taller, but not by much.

The seeds germinated well on all three of the media. But the HM potting mix outperformed the other two microgreen grow mats. 

My Thoughts, Possible Issues, What's Next

Growing Microgreens on Soil

I am a believer that microgreens grow better in a good potting mix. Time after time, the results of my tests show this.

I find soil easier to use, plant, water, and care for the microgreens as they grow. However, it does have some negatives too. It's heavy to shift, good potting mix is hard to find, and it's harder to store.

Growing Microgreens on Hemp Grow Mats

The hemp mat is an excellent alternative to soil if you use a liquid fertilizer. You can see the difference in using a fertilizer with hemp in this two-part article. 

I find it harder to sow seeds on the hemp mat, especially in smaller trays than with soil. A larger planting area gives you more room to spread out the mat. More on this below.

I didn't get a photo of this, but when I took a closer look at the hemp and bamboo mats, I saw that the weave on the hemp mat is looser, more open, than the bamboo mats. This gives the roots an easier time getting established in the hemp mat.

The one negative, and it's a big one, is all of the loose fibers that the hemp mat drops when you touch and move it around.

As I mentioned in this article, I rarely spill soil, but I'd rather clean up some spilled soil than the hemp fibers. They stick to everything. 

Growing Microgreens on Bamboo Grow Mats

The quick short answer is I'm not giving up on them.

The microgreens didn't start out very well. The plants didn't look as good as those grown on either of the other media. The end result produced sturdy, full trays of microgreens. However, they were short and had much smaller leaves.

On the positive side, the bamboo microgreen grow mats are clean, easy to cut to size. There are no fiber issues. I only wish they grew microgreens better.

The bamboo mats didn't perform as well as the hemp mat. But I learned a few things from this test and will be changing up how I grow them. More on this below.

Next Testing Cycle Using Bamboo Microgreen Grow Mats

My takeaways from the testing are these.

The sides of the trays could affect how the microgreens grow on the mats.
So the small trays must go. Maybe the HM tray is not built for grow mats.

The next test will use a 1010 shallow tray, so most plants on the bamboo grow mat will have more light available to them.

We Did the Test!

You can read about the results by clicking the link below.

Bamboo Grow Matting - A Possible Breakthrough for Better Microgreens

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Recommendations

We will still be using Home Microgreens Soil when we grow microgreens. It has outperformed any grow media that we have tried so far. 

As much as we like how clean and neat the bamboo grow mat is and dislike so much how messy hemp grow mats are, we will not be placing bamboo grow mats in the Home Microgreens Store at this time.

If you have a product or brand of grow media you would like us to test, please leave a comment below or reach out to us on the contact page, and we will give it a try.

We want to provide all of the microgreen home growers with the best products we can.