How to Grow Kale Microgreens Perfectly Every Time

Growing Kale Microgreens is straightforward and very easy microgreen to grow. There are a couple of possible problems and we will touch on those as we describe how to grow kale microgreens at home.

Kale has been touted to be a superfood for many years but only recently has research shown that microgreens, especially kale microgreens are more nutritious than leafy green kale.

You should grow kale microgreens not only for nutritional value but also because kale microgreens are less bitter and more palatable to eat raw than mature kale leaves.

How to Grow Kale Microgreens

I will explain how to grow kale microgreens, including how much seed to use, how to germinate the seed, how to care for your kale microgreens, and when to harvest them. 

We will also touch on these easy-to-grow microgreens’ nutritional and health benefits.

What You’ll Need to Grow Kale Microgreens

Here is a list of what you will need to grow kale microgreens.

• Seed (see below for how much).
• I recommend a potting mix containing coconut coir for a growing medium, but you can also use a grow mat.
• A growing tray, which we call a planting tray (planting trays have drainage holes and also let water into the soil when bottom watering).
• A Watering tray, which has no holes and will hold water. (best if the planting and watering trays are the same size).
• Lid or piece of firm plastic (used during blackout period – see below).
• Weight (weight depends on the size tray – see below. I use weight plates but have used rocks, books, shotgun shell boxes, plant pots, and even glasses of water).
• LED light (recommended, but kale can grow in natural light like a sunny window or in lower ambient light locations such as a kitchen counter).
• Scissors or a sharp knife for harvesting.

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Home Microgreens online store sells reasonably priced microgreen seed packets with the perfect amount of seed for Home Microgreens trays. 1010 trays plus ounce, 1/4-pound, and pound bags.

We also carry our own microgreen soil and fiber mats for the home microgreen grower!

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How to Grow Red Russian Kale Microgreens as an Example

When I grow a tray of kale microgreens, I use Red Russian Kale seeds. You can grow any variety of kale using the same methods described below.

I like Red Russian Kale, because of the pink and violet stems they produce. Although a bit more expensive than the other kale varieties, I think they are worth the extra expense. 

Other varieties commonly grown are blue Scotch curled kale, dwarf Serbian, lacinato (dinosaur) kale, and white Russian kale. These all have a white stem and dark green leaves.

I use some of these varieties in my microgreen mixes but haven’t listed them for sale individually as of yet.

Grow Media for Kale Microgreens

Kale microgreens will grow both on fiber mats, such as hemp, bamboo, or coco mats, with no problem. In fact, you can grow them exactly the same way as I grow them on potting mix, except how you water them will need to be modified. 

However, as we have shown, microgreens grow better on soil (potting mix), and we want to grow the best possible microgreens.

I always use a potting mix to grow microgreens (except when I’m testing alternatives).

The Home Microgreens Potting Mix is a coconut coir-based mix with a little bit of peat moss and natural amendments to improve growth.

I have tested many different grow media (and will continue to do so), and the Home Microgreens Potting mix grows great microgreens. Below are some trials.

What Size Tray Should You Use to Grow Kale Microgreens

I don’t know the size of your family or how much microgreens you eat each day, so it’s hard for me to choose for you.

Start Small

It’s a good idea to grow a small tray first.

Because small trays are more manageable with fewer problems, and you will see the process before you scale up. Also, if you’ve never had kale microgreens before, why grow a ton of them at the start? See if you like them and like growing them first.

This is the advantage of the Home Microgreens Tray. It’s small, easy to handle, I have seed packets with the exact amount of seed to use, and it’s a low-cost investment.

Tray Sizes

I use three different-sized trays depending on how much I want to grow. The three trays are:

• Home Microgreens tray with a planting area of ~ 38 square inches
• 1010 tray with a planting area between 95 and 100 square inches
• 1020 tray with a planting area between 190 and 200 square inches

I use the Home Microgreens tray in the example below because it is easier to show. As mentioned, we grow Red Russian Kale, but any kale varieties will grow the same or very similar.

How Much Kale Seed to Use for Each Tray

Many suggest throwing over an ounce of kale seed on a 1020 tray. I’m not sure if they don’t want to take the time to test different amounts or if they are just repeating internet dogma.

But I have spent a lot of time testing seeding density and analyzing the results of using less or more seed.

I believe using an ounce is way too much seed, and the plants don’t reach their full potential by being crowded and fighting for light.

Let’s think about what we are trying to do.

Are we trying to grow as many stems and plants in a tray as we can?

No.

We are growing microgreens to be healthy and nutritious. Growing as much as possible isn’t lost on us but at the expense of lower-quality microgreens.

We are not growing these kale microgreens to sell. The grow media is usually the most expensive cost of growing microgreens, so commercial growers add more seeds than I recommend to lower their overall cost per yield.

They can do this because they take more time to care for their microgreens and usually have more intense lights and fans, increasing air circulation.

I’m going to assume you will be growing your kale microgreens under normal LED lights with no special setup. 

I also have observed that using fewer seeds (to a point) increases the leaf size of the microgreens. 

The nutritional value is in the leaves, not the stems.

Commercial growers sell microgreens by ounce, so they want more weight. Stems are heavier than leaves, and the denser you grow microgreens, the longer the stems grow as the plants fight each other for light.

Therefore, for those of us growing microgreens at home, my recommended seeding density for kale microgreens is as follows.

• Home Microgreens Tray uses 3.3- to 3.5 grams.
• 1010 tray, we use 8.0 to 8.5-grams
• 1020 tray, we use 17 grams of kale seed. 

Home Microgreens sells seed packets packed with the correct amount of seeds for the Home Microgreens and 1010 trays.

I also have a seed density calculator for odd-sized trays and many other microgreen varieties. 

If You Don’t Have a Gram Scale

For reference, a heaping teaspoon of Red Russian kale seed is about 3.5 grams, and a level tablespoon is about 9.3-grams

If you buy seed by ounce, an ounce equals 28.35 grams.

We also have a seed density calculator with output in teaspoons and tablespoons.

How to Grow Kale Microgreens: Planting Seeds

Now that we know how much seed you need, it’s time to get those seeds on the soil.

Take your planting tray, the one with holes in the bottom, and fill it to the top with your potting mix.

Use the bottom of your watering tray (if it fits inside the planting tray) and press down on the soil to compact it.

Good potting mixes will not compact too much.

If your watering tray is larger than the top of your planting tray, use your fingers or cut a piece of cardboard to fit inside the tray.

We want to compact the potting mix to level the soil in the tray and smooth the surface. If you don’t compact the soil before seeding, it might settle unevenly when watered, thus causing the seeds to clump together. 

Smoothing the surface also makes it easier to spread the seeds evenly across the surface and move them around afterward if they are not uniformly distributed.

From here on out, we will call the potting mix soil only because it’s a shorter and easier word to use.

Mist the Soil Surface

Take a spray bottle and mist the surface of the soil. Gently at first so the soil doesn’t blow out of the tray.

Once the surface has been wet, you can spray the surface with more force to get more water on the soil surface.

Spray the soil surface 3 or 4 times. 

The purpose isn’t to completely wet the soil profile.

Many people suggest soaking the soil. 

I disagree completely with that statement.

Germinating seeds do not need the soil wet all the way to the bottom of the tray. This can only cause issues. 

Here is a metaphor that might help with watering microgreens pre- and post-planting.

The probability of large thunderstorms increases when the atmosphere is loaded with water, and it’s very humid.

The atmosphere is unstable and nasty weather is inevitable.

The same thing happens when there is extra water in the soil.

The water doesn’t sit there and wait for the plants to use it. It evaporates, increases the humidity of the air in the soil pores, rises, hits the cooler surface of the blackout dome or the microgreen stems, and condenses.

Water and humidity increase the probability of mold formation.

Mold spores are omnipresent and sit in the soil, on the grow mat, on the seeds, and even on the microgreens in a dormant state, waiting for the ideal conditions to grow.

Soil or grow mats that are too wet provides the ideal condition.

So please, only wet the soil’s upper 1/3rd or top half.

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Planting the Kale Seed

Now that the soil surface is level, smooth, and wet, spread the seeds evenly across the surface.

There is no need to soak the seeds. We don’t soak any small microgreen seeds.

I use a shaker bottle or 250-mL measuring cup to spread the seed. I find it much easier than using your fingers or a spoon.

Slowly shake the bottle or cup to get the seeds moving inside, and tilt the container until a few seeds fall onto the surface. 

Make slow circles around the planting tray and spread the seeds where they aren’t.

When all of the seeds are on the surface, you can use a finger to move them around if you have areas with more seeds than others.

Don’t drive yourself nuts trying to make it perfect, but the more evenly spaces the seeds, the better your microgreens will grow and airflow through the microgreens will be better as they grow.

One More Misting

Gently mist the seeds (so as to not move the seed).

This will wet the seed surface and help make better seed-to-soil contact.

Again, don’t overwet the seeds or soil. One or two gentle mists will work.

Blackout Period

Now is the time to put the tray into a blackout period. Read this article explaining the blackout period for microgreens for more information.

The blackout period is the most commonly used germination process when growing microgreens.

The seeds need to be covered and placed in a dark place with a weight on top for the best growth.

I use the upside-down lid of the Home Microgreens tray as a cover.

For 1010 and 1020 trays, I bought some coroplast from a hobby store and cut it to size. I like to use plastic as it makes great contact with the seed, holds in moisture, is firm enough to handle the weight on top of it, and can be easily cleaned and sterilized afterward.

The purpose of the lid and weight is to push the seed onto the soil surface and force the roots to grow down into the soil to push the weight up off themselves (most can).

Most seeds germinate and grow better in the dark – think of planting seeds in the garden.

How to Place Kale Microgreens into the Blackout Period

Place the tray where it can sit without being disturbed for 3 or 4 days.

Put the lid or cover on top of the tray.

Place a weight on the cover. I use:

• 2-½-pounds for Home Microgreens trays,
• 5 pounds for 1010 trays and;
• 10 to 15 pounds for 1020 trays.

Don’t worry, it’s not too heavy. The young seedlings can lift the weight if need be.

After the weight has been placed on top, I cover the tray with a tea towel or old towel to exclude more light.

You can also stack trays on top of each other if growing more than one tray.

The next step is the hardest.

Do Nothing For 3 days!

Yep, leave them be for three days.

The tray is covered and won’t lose any moisture, so water is unnecessary. 

Checking on the seeds will only disturb the tiny, fragile roots, so don’t peak. 

You will do more harm than good. If anything bad is happening, you can’t do anything about it, or you can take care of it afterward.

Leave kale microgreens in the blackout for three days minimum. Kale seed does not germinate all at the same time. Some seeds will grow in 2 days, and others might not germinate for 4 or 5 days. 

I know I’ve said this three times, but don’t even look at them for three days.

You want to but don’t.

Freeing Your Kale Microgreens

It has been three days since those seeds went into the blackout.

Today is the day.

Remove the towel and the weight, and gently lift the cover.

If they look like the kale microgreens below, they are ready for the light.

They may be more yellow than those shown but don’t worry; they will green up under the lights.

The white are root hairs and not mold. 

However, if the seedlings are smaller or not as well developed, place the cover, weight, and towel back over them and take a look tomorrow.

Many factors affect germination, so sometimes it takes more time.

When your kale microgreens look like those above, it’s time to get them ready to be placed under the lights. 

“Get Them Ready to be Placed Under Lights?

We need to do two things before we place them under lights so the microgreens can turn green and grow.

First Thing

Remember (by feeling) the weight of the tray as you take it out of the blackout. 

The little bit of water that you added to the tray when we sowed the kale seeds has been mostly uptaken by the plants.

So the tray is nearly dry, and the kale needs water. But before we add water, we want to remember how the tray feels in our hands. 

Why?

Because we won’t water the microgreens again until the tray feels this light or the microgreens wilt. More on wilting later.

Learning Statement About Watering

Overwatering is the biggest mistake new growers – all growers – make. People like schedules; schedules make remembering things easier, so we believe microgreens must be watered on a schedule. 

But in reality, things change, such as the humidity, growing rates, foliage mass, loss of soil-to-root ratio, air movement, etc.

Schedules are a human invention that plants and nature haven’t learned yet. There may be cycles, but plants have no schedules when it comes to watering.

Water microgreens and your house plants when they need it, not every other day or only on Sunday mornings.

Maybe you believe I’m being cynical here, but you would understand if you saw as many photos of overwatered microgreens as I do in my emails.

Second Thing

Water the tray before placing it under the lights.

This is the perfect time.

How to Water Kale Microgreen – All Microgreens

Water microgreens from the bottom. 

We grow microgreens in tray sets. The set includes a planting tray (holes in the bottom) and a watering tray (solid base).

Once we mist the microgreens seeds during planting, we rarely – very rarely – water over the top of the microgreens again.

I know a lot of other people do. Usually, these are people growing tens if not hundreds of trays at one time, and those microgreens are grown in larger rooms with more airflow.

In the home, please don’t water over the top. It can only add to the chance of fungus and, worst, bacteria issues.

Bottom water microgreens and keep the greens and stems dry. The soil will wick up water from below, and the roots will receive plenty of water. 

Please bottom water only.

How Much Water to Give Kale Microgreens

How much water will depend on the tray size and what media you use to grow your microgreens.

We have an article that describes watering microgreens in detail. You can read that microgreen watering article by clicking this link.

For the Home Microgreens tray in this kale microgreen article, we use 1/2 cup of water. If you have a different-sized tray, the article linked above will have more information for you.

Kale microgreens can even wilt a little bit before you water them.

Once they are given water, they will stand back upright. Don’t let them go too long without water, but don’t give up on them if they wilt.

How Much Light Do Kale Microgreens Need?

What lights to use for microgreens is a tricky subject. One that even I am trying to wrap my head around.

I have been observing microgreens growing under many different types of lights for years, and the results are confusing. 

We will do an article and podcast on this in the future.

But for now, we must consider what most people will use and can afford and still get results. 

Here are our suggestions for now. But, we reserve the right to change our minds!

LED shop lights of 20 watts with a Kelvin rating higher than 5,000 (published on all light boxes) will work fine. I have multiple microgreen racks that use these Barrina lights. 

You do not need a grow light, but artificial light does help.

Currently I’m working on an article that uses these smaller and inexpensive grow lights. Again, grow lights are not needed for microgreens. But if you’re going to grow lettuce or garden sets, they can be helpful. 

The kale microgreens in this article are grown under the Barrina lights mentioned above. Different lights will change the growth habits of microgreens.

But in the end, the inexpensive LED shop lights work. So start with those, and when you decide you want to upgrade, we will have more recommendations by then.

I leave the lights turned on for 15 hours.

The height setting is between 6 inches and 18 inches above the greens, depending on the power of the lights.

So start with 8 inches above the greens and experiment.

Again, we will have much more on this topic in a future podcast.

That’s right; we have a podcast too. It’s called the Microgreens Podcast, and you can subscribe to it on any of your favorite podcast platforms.

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Can Kale Microgreens Be Grown in a Sunny Window?

The short answer is yes, they can grow with indirect sunlight, as kale doesn’t need as much light as other microgreens.

There will be some shortcomings, though. 

You will have to rotate the tray 90 degrees every day or two. The microgreens will start leaning toward the window. 

Microgreens with red tints, like Red Russian Kale, will most likely not have as much color in the stem.

The general rule is more light intensity; the more color microgreens will have. This includes the green color of the leaves. More light, darker green leaves.

Kale can be grown in low-light conditions. Even on a table or counter that gets indirect light. However, you will still need to be sure the light around the microgreens stays on 24/7.

But for best results, use LED lights, especially in the winter months for those of us in higher latitudes.

Growing Kale Microgreens

From this point on, keep them under the lights and water as they need it. 

Simple as that. 

Watch them grow.

When to Harvest Kale Microgreens

Kale microgreens have a long tray life. By that, I mean you can continue to grow kale in trays well past the formation of the first true leaves.

Microgreens start out growing seed leaves (cotyledons), which we eat most of the time as microgreens.

Seed leaves are oval with smooth edges.

But with kale (and many other microgreens such as mustards), you can hold off harvesting them until their first true leaves form. 

True leaves are more elongated and frilly. 

So When Should You Harvest Kale Microgreens?

I recommend you taste them as they grow and determine at what stage you think they taste the best. 

The longer you grow them, the more care they will need because the root-to-soil ratio will increase, and they will need watering more often. 

So in shallow trays, the sooner you harvest, the easier it will be. 

If you want to grow kale up to baby greens, I recommend using a deeper tray that will hold more soil.

I like them just as the true leaves form.

Harvest kale microgreens when they are 4 inches tall. 

Kale microgreens will reach this height 8 to 12 days after planting them. 

I use scissors or a sharp knife to harvest my microgreens.

Below I have a video of me harvesting some cabbage. The variety doesn’t matter; they are all done the same way. 

Since kale continues to grow, I harvest only what I need for that day and place the tray back under the lights to continue to grow. 

The average yield is about 6 to 8 ounces from a 1020 tray.

What Has More Nutrition, Seed Leaves or True Leaves?

I have no idea. There is so little difference between the two, especially for the number of kale microgreens we will eat, that it’s a wash.

The health benefits of kale microgreens are well documented.

Kale microgreens have concentrated levels of vitamin A, vitamin B6, vitamin C, vitamin E, and vitamin K and calcium, iron, magnesium, potassium, and phytonutrients, including polyphenols, glucosinolates, flavonol compounds, and carotenoid antioxidants to help the immune system.

Click the link to read an article I published on kale microgreen nutrition.

Also, subscribe to the podcast for updates (below), as I will discuss my thoughts on microgreen nutrition soon. 

What Do Kale Microgreens Taste Like?

Kale microgreens taste less bitter and are not as astringent as kale leafy greens.

They have a slight sweetness to them. I think they taste like a mix of broccoli and red cabbage microgreens.

Again, they don’t have the strong flavor profile of mature vegetables.

Kale microgreens are also plumper than other brassica microgreens. For a better lack of a texture term, they are meaty.

Summary of How to Grow Kale Microgreens

You can purchase Red Russian Kale microgreen seeds from the Home Microgreens Store.

For every square inch of the tray, we plant 0.09 grams of seed. 

We use the weighted blackout method to germinate the kale seed.

The seed stays in the blackout between 3- and 4 days.

Any light will work for kale microgreens, we used low-wattage grow lights, but any LED shop light with a K-value of 5,000 will work wonderfully!

Water kale microgreens when they need water. When the tray feels light, water them. 

Grow them under lights between 8 and 16 days. 

It’s best to harvest before then as the stems become quite woody.

Kale microgreens do have a good shelf life.

The 12-day mark would be an excellent time to harvest these flavorful microgreens.

I hope you have a great experience growing these nutrient-dense microgreens. Kale microgreens have a less bitter taste than mature plants,

If you have any questions, feel free to email me.

Do You Have a Pinterest Microgreen Board?

If not, why not start one! Use this pin as the first or add to your existing boards.