Kale is a superstar vegetable that needs no introduction. Kale is the most nutritious microgreen with regards to vitamin and mineral content.
The biggest drawback of growing kale microgreens is the cost. Kale seeds are four times more expensive than broccoli without providing four times the amount of nutrients.
So why grow kale microgreens at all? Well, if you’re like me, you have some kale growing in your garden and are growing seedlings for the next season.
A single kale plant needs about four square foot of space to grow in your yard to grow to its full potential. Even if you designate 100 square foot in your garden, you will only need 25 seeds to fill up the entire garden. It's not good practice to keep seeds for multiple years.
Kale microgreens has less antioxidant capacity than peas, amaranth and broccoli. That said, the antioxidant capacity of kale is within 10% of broccoli microgreens, which is respectable given that broccoli microgreens have 5 to 10 times higher antioxidant concentration than the mature vegetable.
Kale also have a lot of vitamin A, B, C, E, K, and various nutrients such as iron, calcium, potassium, phosphorus, and selenium. And compared to broccoli, kale has four times the amount of vitamin K, calcium and manganese.
For growing kale microgreens, I use a combination of peat moss and 10% vermiculite. And since the growing timeframe is around 3 weeks, I also add fertilizer to 0.5% Nitrogen by weight to enchance nutrient availability.
Since peat moss repels water when dry and compacted. The medium should be mixed with water vigorously prior to usage. If you are planning to transplant some kale into your garden, it's important to increase the depth of the medium to at least 2.5 inches. This would allow microgreens to be harvested without harming the potential transplants's roots.
Soaking kale seeds is not necessary. The experimental results from soaking broccoli and turnip seeds suggests that soaking did not increase the rate or amount of germination.
The maximum seeding rate for kale is the same as broccoli at 20g/ square meter or 1/32th ounce per square foot. However, ideally 10g/square meter or 1/32th ounce per square foot would be reccommeneded for transplants.
To ensure proper germination, either cover the seeds with 1/2 inch of growing medium. It's very important to keep the surface of the growing medium moist during germination.
After three weeks of growth, kale microgreens should be about 1.5 to 2 inches in height. At this point, the third leaf should be fully formed. Make sure to check the bottom of the container to make sure that the roots are not balling up. If so, this means that there was insufficient growing medium for kale.
To harvest the kale microgreens, pull them out straight from the growing medium. If you are growing transplants as well as microgreens, allow the remaining plant to recover in the growing container for 3 to 4 days.
Since kale matures in 100 days, the best time to grow kale microgreens is in the spring and late summer for a bi-annual harvest. If you are transitioning kale that were grown indoors to outdoors, make sure to habituate the plants to outdoor lighting conditions.
Keep the kale transplants in the shade for at least one week before transitioning to full sun. Plants have to adapt their leaves to full sun conditions or else they will get sunburnt.
If you are growing kale for yourself, you can ensure a weekly harvest by only harvesting the older leaves. Growing kale is the most economical vegetable when you consider partial harvests into account.
When you’re growing kale outdoors, also look for when the brassica moths (white moths) are around. Make sure to wash off any moth eggs before consumption.
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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.