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 seed somewhere, doesn't matter where, and water them."
For that reason, 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 a couple of unique characteristics for radishes, making them a worthwhile microgreen and garden radish. 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
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 would like to refer you back to that article to see the specifics for 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.
The photos below show both 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 exactly 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 real 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, is very large.
Both the Triton and SaiSai have average-sized seeds for radishes.
For both of these radish varieties, we use 5.4 -grams on a Home Microgreens planting tray. 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 coconut coir based potting mixture.
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 towel.
This is called the blackout period. It simulates the seeds being covered by soil. The weights help push the seeds on to 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, take a look at the trays by removing the towel, weight, and lifting the lid carefully to not upset seeds trying to root.
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 are ready to come out of the blackout period.
Put the lid, weight, and towel back 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 actually lift and throw the weight off the tray! So don't wait too long.
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.
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Notice how the root hairs have disappeared (entered into the soil?). The SaiSai radish photo is taken about 2-hours after they were placed under the lights.
It doesn't take long for the plants 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 be turning the trays 90-degrees every day 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.
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, 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 water to the watering tray and lower the planting tray down into the watering tray.
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 a bit of 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!
Let Them Grow - But Not Much Longer
At this point, check their need for water every day. You can tell when they need water as the tray will feel light.
Water is heavy, and when the soil is even a little damp, you can feel its weight.
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 that 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 quick.
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 begin to 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 give them a try!
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 - 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 a pair of 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. We put several holes in the bag with a knife, and squeeze the air out of the bag.
Then we place them in the refrigerator crisper.
The microgreens will last a week or more when harvested in this fashion.
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 on the stems just gets brighter red the longer they grow.
But like any microgreen, you have to 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 grow older and see if you enjoy the taste and texture.
Available Radish Seeds
Below are the radish seeds we have 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.