The short answer is no, microgreens do not regrow after cutting. Even mature plants struggle to re-grow after cutting. The only way to regrow microgreens after cutting is by harvesting their non-growth tip. That said, this article will scientifically prove with experiments whether microgreens regrow after cutting.
In this experiment, I have grown pea microgreens that I've grown for 1.5 weeks. They are about 1.5 inches in height from the root ball and are ready for harvest.
As you can see, the cotyledon is still attached and is at a considerable size. You can continue the pea microgreens for another week without encountering any issue even in the absence of a light source.
I used a pair of scissors to harvest the greens, cutting it at the base above the cotyledons. The scissors were sterilized with rubbing alcohol to reduce the possiblity of infetion. The pea microgreens has enough stored carbohydrates stored in the cotyledons to re-generate an entirely new tip. The roots has enough reach such that it doesn't dry out.
After leaving it for 3-4 days, you can see that it doesn't grow back, even with the energy stored in the cotyledon structure. The next sections will explore why you don't see plants re-growing after you cut them.
When you cut a plant, you're making a major wound to their vascular system. Therefore, the plant's first priority is to repair the wound.
The cells at the tip of the plant die off, forming a barrier of cells. If you look closer at the experimental photos, the tip of the cut are greyed out. The problem with cutting plants at the base is that these cells are already differentiated.
Stem cells are cells that can differentiate into any type of cells. By the time that the plant is already fully formed (have a stem, leaf, tip and root), most of the plant's stem cells are located at the growing tip. This means that the cells located at the base can only differentiate into the same type of cells.
Even in cases where new growth tip emerges (basil clonal propagation), the growth pattern is disrupted, forming a crooked plant.
An open wound is a vector for infection for microbes, and we can't just sterilize the wound with rubbing alcohol. The number one killer of young plants are fungus.
If you ever notice white fuzzy strands that are killing your seedlings, that's fungus. Fungus are opportunistic. Their spores are virtually indestructible and ubiquitous. The only way to avoid fungus is to grow microgreens in a biosafety cabinet, which is very costly and impractical.
Life finds a way. Fungal spores will find a way into that open wound, especially when the wound is the size of the grand canyon compared to the spore. Moreover, fungus thrive on humidity and moisture. So if you cut your plant and decide to water it, it's game over.
Plants are especially vulnerable to infections when they are young. This is why they are enriched in the cancer-fighting and antimicrobial phytochemicals. The process of generating phytochemicals is extremely energy intensive.
So the plant have to not only spend energy on re-growth but also on defense. And if the energy stored in cotlydeon or root ball is too small, the plant will simply die.
Assuming that you're growing your microgreens in a sterile environment, is there a chance that a cut plant will regrow? yes*.
But it's not worth the effort. There are only two cases where I've regrown plants, both using kale as an example.
For the first case, the plant was completely eaten up by cabbage moths. At this point, the plant was about 6 inches in height and 1.5 months old. So I decided to cut it at the stem and see what happens. To my surprise, it started to regrow a new leaf from the side of the stems. However, this plant remained only 3 inches in height for the rest of the growing season, while all of my other plants grew to 12 inches in height.
For the second case, when the plants were 12 inches in height, I would harvest the older leaves. This allow them to growth tip to remain intact while allowing me to continously harvest week after week. But the downside of this method is that you can't do this sustainably with microgreens. It's too labor intensive and not worth the time.
If you let your microgreens develop the third true leaf and only harvest the older one, by the time the leafs regrow (2 weeks), the plants would be a lot older and not as nutrituous. Plants that are damanged have an entirely different gene expressions and chemical makeup versus plants that are growing in the exponential phase.
You have to start thinking of your microgreen farm as a business. Is it worth regrowing an entire container when you can start a new batch? Space is the most valuable factor when you're growing microgreens. If you cut your plants, and only 50% survive and regrow to full size in two weeks, you're using up space that can be devoted to growing 100% full sized plants in the same timeframe. Moreover, the newer plants are more nutritous and contain less microbial content.
Plants cannot grow live cells from dead cells, that would cause a zombie apocalypse. New leafs will have to grow from the side of a live stem. When they are small, this will cause the plants to stick close to the ground, which is bad because the entire leaf surface will now be a vector for fungus. This will cause more plants to die off, further decreasing yeilds.
In conclusion, just regrow an entire new batch. It may not seem like it, but it saves you money.
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I am the author of this website and owner of growyourmicrogreens.com. I am an hobbyist gardener and a passionate scientist. I was trained as a scientist in the Molecular Genetics program in University of Toronto, where I received my Masters of Science and published a journal article.