How to Grow Radish Microgreens Using My 2 Favorite New Varieties

Radishes are one of the easiest microgreens to grow. A how to grow radish microgreens article can be summed up by saying, “Throw a bunch of seeds somewhere; it doesn’t matter where, and water them.”

Therefore, we ranked radish microgreens number one in our 6 Easiest Microgreens to Grow article.

This article will describe how to grow radish microgreens using our two favorite radishes, Triton Purple Stemmed and SaiSai Red Stemmed Radishes.

You may not have heard of SaiSai radishes; they’re new to us too.

They have some unique characteristics for radishes, making them worthwhile microgreen and garden radishes. We’ll discuss those characteristics later on in the article.

Isn’t the SaiSai Radish below stunning? Notice the true leaf forming on the center plant.

how to grow radish microgreens saisai radish

How to Grow Radish Microgreens

We published an article a while back called Growing Radish Microgreens. There’s absolutely nothing wrong with that article regarding growing radish microgreens, except maybe using opaque trays.

We want to refer you to that article for the specifics of sowing and growing radish microgreens. Click this link to read that article

We will add content that the previous article didn’t include. And show photos of radish microgreens as they progress through the growing stages.

home microgreens sells seeds

FREE Home Microgreens Grow course that teaches you the basics of growing microgreens in your home! There are 12 video lessons (over 120 minutes), downloads, and more written information and tips!

The photos below show Triton Purple Stemmed Radish and the SaiSai Purple Radish side by side (when viewing on a computer) or vertically (on mobile) with the Triton Radish first.

Also, Check Out The True Purple-Red Leaf Radish

Radish terminology is misleading. Many radishes are referred to as “purple or red,” and many, myself included, are often confused about what part of the plant is purple or red.

Both of these radishes are referred to as purple. But only the stem is purple. The leaves are green to dark green. 

To us, the actual red radish is the Purple Rambo Radish. There are many other varieties, such as Purple Sango and Red Vulcano.

Still, we think the Rambo Radish grows the best. Here’s an article on how to grow the Rambo Radish.

How to Grow Radish Microgreens – The Seeds

The size of radish seeds varies quite a bit. All can be considered large in the realm of microgreen seeds, but some, such as the Rambo Radish, are very large.

Both the Triton and SaiSai have average-sized seeds for radishes.

Triton purple stemmed radish seeds

Triton Radish seeds (5.4 grams) in a tablespoon

saisai radish seeds

SaiSai Radish seeds (5-4 grams) in a tablespoon.

We use 5.4 grams on a Home Microgreens planting tray for both of these radish varieties.  That’s about 0.15 grams of seed per square inch. 

Sowing Radish Seeds

We use a Home Microgreens planting tray filled with our premium potting mix. The potting mix is a coconut coir-based potting mixture. 

Triton purple stemmed radish seeds

Triton Radish Seeds 5.4-grams planted on a Home Microgreens Tray

SaiSai radish seeds planting on a home microgreens planting tray

SaiSai radish seeds 5.4 grams planted on a Home Microgreens tray.

The potting mix is lightly tamped to level out the surface and then misted 3 or 4 times to wet the upper third of the soil profile.

The seeds are evenly spread on the soil surface and misted to wet the seeds.

Place Seeds Into a Blackout

We place lids on the trays, stack them on a shelf, add three to five pounds of weight on top of them, and cover them with a tea towel.

Below is an example minus the tea (kitchen) towel.

Stacked microgreen trays

This is called the blackout period. It simulates the seeds being covered by soil. The weights help push the seeds onto the soil to get better seed-to-soil contact.

The lid helps with this and also retains moisture. The towel helps exclude light from the seeds.

Leave the seeds like this for 48 hours. 

How to Grow Radish Microgreens – Germination After 2-days

Near the 48-hour mark, look at the trays by removing the towel and weight and lifting the lid carefully not to upset seeds trying to root.

triton radish microgreens after 48-hours

Triton radish microgreens 48 hours after planting and removed from the blackout period.

saisai radish microgreens 48-hours after planting

SaiSai Radish microgreens 48 hours after planting and removed from the blackout period.

The radish seedlings are yellow due to the lack of light.

The white isn’t mold or fungus. Those are root hairs along the seed radicle.

This is a very common question, but there’s nothing to worry about.

Because the root hairs are still showing, neither of these radish microgreens’ trays is ready to come out of the blackout period. 

Put the lid, weight, and towel on the tray and wait at least one more day. 

Radish Microgreens Ready to Go Under Lights

Radishes grow quickly, so check them the next day. Sometimes it’s obvious when they’re ready for the lights. 

The little greens will lift and throw the weight off the tray! So don’t wait too long.

radish microgreens lifting off weight

Triton radishes throw another tray and weight off themselves.

How to Grow Radish Microgreens – Knowing When to Put Them Under the Lights

Usually, radish microgreens are ready to be taken out of the blackout and placed under lights on day 3.

Unlike the tray in the previous photo, we waited too long (probably day 4). They decided to expose themselves to the light by tipping off the weight and tray above them.

Our Triton and SaiSai radishes are right on schedule.

triton radish microgreens on day 3

Triton radishes after 72 hours in the blackout. Notice the root hairs have disappeared. These microgreens are ready to go under the light.

SaiSai microgreens on day 3 and under light

SaiSai radish microgreens three days after planting and under the lights for about 2 hours. They are already turning green and reaching for the light.

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Notice how the root hairs have disappeared (entered into the soil?). The SaiSai radish photo was taken about 2-hours after they were placed under the lights.

The plants don’t take long to start producing chlorophyll and turning the leaves green. 

Take radishes out of the blackout when the root hairs disappear, and the plants start standing upright and lift the lid off the soil surface.

What Lights Should Be Used?

 Anything from sunlight to mid-range grow lights. We use either cheap LED shop lights like those the SaiSai radishes are under to LED T5 tube lights from Barrina (We will be trying their grow lights soon – about 40% in cost, though).

With sunlight, you’ll turn the trays 90 degrees daily as the microgreens will grow strongly toward the light.

We prefer  Barrina lights (right now). They are inexpensive to buy and use, and they do the job.

However, the mid-range grow light from Mars Hydro might turn the stems darker purple and brighter red than the Barrina’s.

This is something we need to test.

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.

how to grow radish microgreens pin

Watering Radish Microgreens

Besides misting the seeds when we planted the radishes, we haven’t watered the trays. 

Now that the microgreens are out into the light and producing sugars, it’s time to water. 

Do Not Water Over The Top

Whatever you do, don’t water over the top. It can only cause problems with mold, fungus, and bacteria, and your greens get dirty. 

This is why the Home Microgreens trays come with a watering tray.  

When the microgreens go under the light, we add about 1/4 of the watering tray and lower the planting tray down into the watering tray.

You can see this in either the start-up video on the Home Page or the Growing Radish Microgreens article.

On the second day, again add 1/4-inch to a 1/2-inch of water.

Caring For Your Radish Microgreens

There’s not much care needed for radishes. 

Put them under the lights, add water, and let them go.

Within 24 hours, the leaves will form and stretch toward the lights. You’ll be surprised how fast they grow!

triton radishes 4-days after planting

Triton radishes four days after planting. They are already 2 inches or more tall, and the stems are starting to color up.

Saisai radish microgreens 4-days after planting

Saisai radish microgreens four days after planting. They’re a bit taller than the Triton, and the stems are a darker purple as some start turning reddish.

Let Them Grow – But Not Much Longer

At this point, check their need for water every day. You can tell when they need water; the tray will feel light.

Water is heavy, and you can feel its weight when the soil is even a little damp. 

Radish microgreens transpire much more than other microgreens, so planting them too densely without good air circulation can lead to mold and fungus issues.

Radish microgreens are one of the few we place on a shelf with a small fan blowing across them from day-4 onward. 

Be aware of the moisture on the plants in the middle of the tray.

The wait isn’t much longer, though. In some cases, radish microgreens can be harvested in 5-days. Usually, it’s 6- or 7-days, but they grow quickly.

triton radish after 6-days

Triton radishes from seed to harvest in 6 days.

SaiSai radishes 6-days after planting

SaiSai radishes are ready to harvest in 6 days.

Short Harvest Window For Radish Microgreens

Unlike many microgreens, radishes have a short window because of their fast growth. 

With radish microgreens, you have about a two, maybe a three-day window for harvest.

After this point, the radishes start to grow their first true leaves. The stems and leaves grow hairy and fuzzy and are unpleasant to eat.

SaiSai Radishes as Baby Leaves

However, SaiSai radishes act a bit differently. 

The stems and leaves are “hairless,” and they can be grown larger to what is known as the baby leaf stage. Similar to small beet greens or baby leaf lettuce.

Given 30 to 35 days and more space, SaiSai radishes can be grown to the sizes shown below.

Try SaiSai Radishes In The Garden

Use the same seeds in the garden next year and try them!

SaiSai baby leaf stage
baby leaf saisai radishes

SaiSai radish would have to be sown at a much lower seeding density than the ones shown above to grow them to that size.

However, it is possible to eat SaiSai radishes once the true leaf forms, unlike other radish varieties.

how to grow radish microgreens saisai radish

True leaf forming on SaiSai radish. This radish variety doesn’t get the fuzzy growth that others do once true leaves form. The red color becomes brighter at this stage also.

How to Grow Radish Microgreens – Harvest

Due to the shorter harvest window (aka quick growing), radish microgreens will most likely have to be harvested by the eighth or ninth day.

We use a sharp knife or scissors and cut the radish microgreens about 1/4-inch above the soil.

Again, be aware of the moisture levels on the stems. Too much moisture will shorten their shelf life. 

We place the cut microgreens in a zip-lock bag. With a knife, we put several holes in the bag and squeezed the air out.

Then we place them in the refrigerator crisper. 

The microgreens will last a week or more when harvested in this fashion. Since this post was initially published, we have devised a better way to store microgreens. You can see our method in this article.

harvested triton radishes

Harvested Triton radishes have pink to purple stems.

Saisai radishes during harvest

SaiSai radishes have pink, purple, and red stems. The red brightens with maturity.

Here’s where SaiSai radishes shine. The harvest window is longer because the stems and leaves don’t grow those hairy, prickly things that other radishes do. 

Also, the color of the stems gets brighter red the longer they grow.

But like any microgreen, you must choose when to harvest your microgreens based on taste.

For instance, some people like kale after the true leaf forms. We would rather eat them before that stage.

The first time you grow any microgreen, leave some to age and see if you enjoy the taste and texture.

Available Radish Seeds

We have many radish varieties available for sale in the Home Microgreens Store.

Always check for more by typing radishes into the search box to see if we’ve listed others.

Give Radish Microgreens A Try

Radish microgreens are great for the beginner.

And those that want to add a bit of fresh spice and flavor to their sandwiches, burger, nachos, tacos, and of course, salads. 

We hope this how to grow radish microgreens article was helpful. We recommend you try to grow these two excellent radish microgreens.


  • Todd

    Todd is the founder of Home Microgreens & the Home Microgreens store. He also writes for several other websites, including MyViewFromTheWoods.com. Todd worked at a large farm market, garden & nursery center for 20 years. Somehow he snuck off to become a geologist and professor before coming back to his senses to write & lecture about microgreens and gardening. When not at the computer, he can be found in the garden, trout stream, or mountain trail with his new Springer Spaniel Caden.

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