It takes anywhere from one to four weeks after seeding to harvest microgreens. The beauty of growing microgreens is that you can grow it to any stage, and harvest it at the flavor profile of your liking.
The process of growing 1 week microgreens is error-proof. For the first week of growth, the plants can grow up to 1 inch in height without light energy. All you really have to do is add water. You don't need complex medium mixes or lighting in order to succeed.
The vegetables that are grown for one week as microgreens are peas, sunflower, quinoa, and amaranth. While these microgreens can be grown for longer than one week, quinoa and amaranth have their highest antioxidant content one week after germination.
Peas on the other hand, have such a big head start in terms of stored energy that they can grow up to 1.5 inches one week after germination.
Sunflowers are harvested at one week after germination because their true leaves are inedible compared to their cotlyedons. You will be forced to harvest sunflower right at the point where their true leaves emerge.
To grow two week microgreen well, you have to pre-plan the lighting, density, and moisture. But it doesn't take more time to prepare than growing one week microgreens.
The reason why 2 week microgreens are harder is because of the threat of infectious fungus. Fungus thrives on moisture. A novice grower that overwaters migrogreens will inevitably run into fungal problems and asphyxiated plants. Conversely, underwatering is going to cause plants to dry out.
A very easy hack to prevent both scenarios is to use a growing medium that supports high aeration and moisture availability such as peat moss and vermiculite.
At the two week after germination, you can get an early harvest of the brassica family of microgreens such as broccoli or turnip.
You can also let pea microgreens grow for two weeks, where you will get two or three sets of true leaves and fully spent their stored energy.
Three weeks after germination, plants will compete fiercely for space. Microgreens that are seeded to densely will begin to wither or stunt.
An overcrowded growing space is also at high risk of fungal infection. And when the plants begin to wither and die, an overseeded container will likely yeild less than a lower seeded container, causing massive waste of seeds.
The varieties of microgreens grown for three weeks are the brassica family of plants such as kale, broccoli, radish and arugula. The three week stage is the most optimal time to harvest the most cost-effective yeild out of brassica microgreens.
4 week microgreens are the most costly microgreens to grow. This is because the growing space taken up by 4 week microgreens can be used by double the amount of 2 week microgreens.
Moreover, the density of seeding of the 4 week microgreens are a lot lower, meaning that they will take up even more space.
The plants that are grown as 4 week microgreens are usually herbs such as basil. However, you can harvest basil at three weeks instead of four to optimize costs. Most people don’t grow basil from seed because they can be propagated clonally. Although basil microgreens antioxidant capacity are very high, their beneficial oils are proportional to the volume and not stage of growth.
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.