Purple basil, also known as dark opal basil is shown in the microgreen sprouting phase of the plant, in this file photo.

How To Grow Purple Basil Microgreens

An Ultimate Guide To Growing Purple Basil Microgreens From Organic Seed 

Growing microgreens is an immensely rewarding experience.  They grow at a fast pace which means you can have a lot of microgreens on a regular basis.  But, do you know how to grow purple basil microgreens? I went out and picked up a big bag of organic purple basil seeds to grow them myself and teach you how I did it.  I’ve also researched from a ton of great sources to bring all that information and experience to you here in one place. So, sit tight and join me, Farmer Jer on another gardening and growing adventure.

“I love growing my own food.  Microgreens are an excellent source of all kinds of great vitamins and nutrients the body needs.  That’s why microgreens are my go-to for a staple part of my diet.”

Farmer Jer

Purple Basil Information

Name(s) of Plant

Common basil is also known as Ocimum basilicum.  Purple basil is commonly known as either Purple Ruffles Basil or Dark Opal Basil, depending on the exact variety.  These two variations are commonly found mislabelled and/or named incorrectly.

Type of Plant

Basil is an annual herb with some variations bordering on tender perennial.  

Kingdom

Plantae

Order

Lamiales

Family

Lamiaceae

Genus

Ocimum

Species/Variations

The common species is Ocimum basilicum.  The issue with basil is that it is confusing due to the number of cultivars of the species.  There are at least 60 variations. The basic consensus, however, is that most common forms of basil are derived from sweet basil.  I like to work with purple basil (Ocimum basilicum ‘Purpurescens) for the purpose of cultivation as a microgreen.

Close Relatives (Common Basil Types)

Scientific NameCommon NameLeavesFlowersNotes
Ocimum americanumLemon BasilPale dull greenWhiteExcellent in vinegar with a strong lemon fragrance.
O. Basilicum ‘Anise’Anise BasilPurplish greenWhiteThis basil has a sweet anise fragrance as well as flavour.
O. Basilicum ‘Cinnamon’Cinnamon BasilYellowish to dark greenWhiteCinnamon basil is as its name implies. There are hints of cinnamon flavor and aroma to this basil variety.
O. Basilicum ‘Crispum’Lettuce-Leaf BasilVery large, crinkled green, sometimes with hints of purple.WhiteThis form of basil is an excellent addition to salads.
O. Basilicum ‘Green Ruffles’Green Ruffles BasilLime green leaves with serrated edges. The leaves are much longer than common sweet basil.WhiteGreen Ruffles basil is often used for ornamental, and aesthetic purposes.
O. Basilicum ‘Minimum’Bush Basil1-1/2 inch long or 3.8 cm long leavesWhiteBush basil is great for growing in pots due to its compact form compared to other basil types.
O. Basilicum ‘Piccolo Verde Fino’Piccolo Verde Fino BasilLeaves are green, 2″ in lengthWhiteThis variety of basil grows to between sweet fine basil and common sweet basil in size.
O. Basilicum ‘Purple Ruffles’Purple Ruffles BasilDark maroon to purple and shinyLavenderThis basil is excellent as a garnish or in vinegar. It has a striking, ornamental, and almost exquisite appearance making it a great aesthetic addition to any herb garden.
O. Basilicum ‘Purpurascens’Dark Opal BasilDeep purple, shinyLavenderThis basil is excellent as a garnish or in vinegar. It has a striking, ornamental, and almost exquisite appearance making it a great aesthetic addition to any herb garden.
O. Basilicum ‘Thyrsiflora’Thyrsiflora BasilBright green, smoothWhite and deep lavenderOften used in Thai cooking, this form of basil has a delicate and sweet flavor and aroma.
O. gratissimumClove BasilGreyish green and hairyWhite with yellow anthersThis close relative has a strong and spicy flavor with a clove fragrance.
O. kilimandscharicumCamphor BasilGreenWhite with red anthersThis close relative has a camphor scent. It is not commonly used in cooking but is used in some parts of the world as a tea for helping with stomach aches and colds.
O. sanctumHoly BasilGrayish green, coarseLavenderHoly basil has a sweet fragrance, although it’s not typically used in culinary. This form of basil makes a nice ornamental plant. It is considered a tender perennial.

Plant Origin

Despite what anyone in Italy may tell you (they do love their basil in cooking, let me tell you), basil actually originated in India.  The plant was distributed across Asia and into Europe and Asia via the spice routes and the spice trade. In the following picture By [SOURCE] Whole_world_-_land_and_oceans_12000.jpg: NASA/Goddard Space Flight Centerderivative work: Splette (talk) – Whole_world_-_land_and_oceans_12000.jpg, Public Domain, [/SOURCE] the red line shows the major trade route known as the Silk Road.  The blue shows the major trade routes via water which were utilized in moving spices, textiles, and herbs like basil from Asia to Europe and Africa.

A map showing the ancient Silk Road trade route and water trade routes of Asia to Europe and Africa are shown in this file photo.
The Silk Road (red-land trade route) and water way trade routes from Asia to Europe and Africa.

Blooming

Basil is a summer flowering herb.  

Description

Basil is an annual, flowering herb.  The stems are leafy. This gives the plant a bush-like appearance.  The stalks shoot upwards from the bush like main body of the plant to expose a near bare stem save for rows of tiny flowers. 

Plant Height

1 – 2 feet or 30 – 60 cm

Leaves

Basil leaves are yellowish green to dark green to purple, depending on the particular type.  The purple basil in particular has leaves that are dark maroon to purplish green and shiny. The leaves form opposite each other in pairs along the stems. 

The leaves form in an oval shape and have toothed edges.  They curl inward, along the leaf ribs giving the leaves an almost umbrella-like expression.  The leaves of the basil plant grow up to 3 inches or 7.6 cm in length. 

Flowers

The basil flower is white to lavender depending on the particular plant variation.  The flowers are typically ½ inch or 1.2 cm long, and two-lipped. The upper lip of the flower has four lobes.  There are four stamens on each as well.

Seeds

Commonly the seeds for basil are small, and dark brown in color.  The size ranges but they typically are no more than ⅛ inch or 3 mm in diameter.  The purple basil seeds are no exception to the size, but they are more of a dark bluish grey in color.

Variety Specific: Purple Basil

This form of basil has deep purple, shiny leaves and the microgreen starts with round, almost circular shaped starter leaves.  The shoots are a bit slow to grow, even at 76 degrees Celsius. The shoots appear a whitish purple color, leaning on the white side of things.  

Basic Information

Basil is a commonly known herb used in a variety of dishes seasoning.  The herb has been used by humans, likely for thousands of years, from Africa to Asia.  Commonly sweet basil is found in almost every kitchen in North America.

Basil consists of a variety of about 14 varieties commonly found in use.  The type which I have chosen to focus on is the purple or dark opal basil as some call it, or O. Basilicum ‘Purpurascens’, from Israel. An organic variety, it is quite easy to sprout but a little trickier to grow than something like green kale. 

Growing Techniques

Growing microgreens is pretty easy and is straight forward.  Purple basil is no exception. All you need to do is figure out how much seeds you need for the size of the growing tray you are using.  I read online that a 10” x 20” tray will use about an ounce of seed. I weighed my seed and found that a tablespoon of seed weighed in at 10 grams.  Well, an ounce is 28 grams, so you need about 3 tablespoons of Purple Basil seed for a 10” x 20” tray.

The trays that I use are actually meant for food storage.  I also picked up trays which are about ⅙ the size of the 10” x 20” tray.  So, I’m using ½ tablespoon of seed per tray.

When starting the microgreens, take your measured seed amount and put it into a mason jar.  I like to use cheesecloth over the top and use the 2 piece lid that has the ring that screws onto the jar and a separate jar ‘plate’.  Set the ‘plate aside and just use the ring to hold the cheesecloth over the end.  

Next, pour cold water into the jar and rinse off your seed.  A single rinse is all that is required. Pour out the water and dispose of.  Keep your wet seeds and set aside.

The next step is to disinfect your medium.  I spray a little hydrogen peroxide and let it sit for an hour.  Then I rinse with some tap water (tap water in my city has chlorine in it to keep it sterile).  Then I put the mat into my tray and pour about ¼ cup of water (1.5 cups approximately for a 10” x 20” tray).  Basically, it’s enough water to soak the mat without having it submerged.

Take your wet, rinsed seed and evenly spread onto your wet mat.

Spray one more light misting of hydrogen peroxide to avoid any mold and cover the tray.  Keep the tray in a warm, dark place (if the tray is opaque and so is the cover, then no problem).

Check on the seeds twice a day, misting lightly with water to keep moist but avoid soaking the seed.  The seed does best when moist and too much water will form mold. This is really about juggling moisture and growth to avoid mold.

In a few days, with misting twice a day, you should start to see the seeds sprouting.  If any mold starts, keep using hydrogen peroxide.

Pro Tip:  Keep your hydrogen peroxide in opaque bottles as it will chemically break down in light.

Once the sprouting has started, remove the cover/lid and place it under a light source.  I use LED grow lights myself, but you can even just set in a window sill (as long as it isn’t too cold by the window).

I like to use a small computer fan at this point to make sure that there is a decent amount of air circulating over my sprouts.  This really helps prevent any kind of mold. The downside is that you may need to mist or water the sprouts a bit more than twice a day as the fan will dry them out faster.  Again, you’ll just have to figure out your balance between breeze from the fan and your sprouts growing mold or drying out. Don’t be upset if you lose a few trays in the beginning as you are learning the balance between moisture and breeze.  That’s one reason why I started with small trays instead of big trays. If you lose a few, you won’t lose all your seed. It’s a shame to lose an entire tray at this stage while you are learning, so start small and get your method down to a science before you graduate to large trays.

Seed Coverage 

1oz (28grams) of seeds for a 10” x 20” tray.

Soil pH

The optimum pH for most types of basil is 6.0.  The plant prefers this ever so slightly acidic soil and with a 6.0 the plant will thrive.

Soil Type

For microgreens, you really don’t need soil, depending on when you intend to harvest.  I recommend using coconut coir mat or hemp mat instead. The reason why I prefer using either coconut or hemp mat is that it is easy to use, easy to cut to size, easy to sterilize and doesn’t make a mess all over like soil does.  This is especially important if you grow your microgreens indoors such as I do. The last thing I want is soil all over the place. I used to grow wheatgrass in the soil until the day I accidentally dropped a 10” x 20” tray in my basement.  That was a huge mess to clean up as the soil had just been watered.

Light

I don’t put my purple basil microgreens under the lights until day 6 or so.  There’s no point until the leaves are at least ⅛” in size. When the little baby stalks have started to reach up, and you see the little purple leaves starting on the whitish stalks, that’s when you put them under lights.  I have used LED lights specific for plants, I’ve also used 4’ florescent lighting that I bought at a hardware store. I don’t think it really matters all that much in the first couple of days, as long as you provide some sort of half decent amount of light.  The plants will start to grow the cutest little purple leaves and they really will want a decent amount of light from day 9 and onward. Keeping them under my LED lights has been able to achieve tremendous results with my other plants, but the basil seems to only get about 2” tall under these lights.  Since I am harvesting them at that time for use as a microgreen, that is acceptable to me. But I would like to test some other lighting systems on them to see which provides the stellar results I’m really looking for. Like the sort of results I’m getting from my green kale under the LEDs. That would be nice.

If you are growing purple basil to full plant maturity (maybe you want to get some seed for next years planting?), then FULL SUN is without question, the best for basil.

Watering

Initial Sprouting – 2-3 Days

When you initially sprout these seeds, there is no need to soak.  Simply sprinkle the seeds on your growing medium and spray thoroughly with fresh water.  You don’t want to drown them, but initially they should be nice and wet. Now, if you’ve pre-soaked your medium ahead of time, you may not want to douse them, just give them a good spray down.  You’ll notice the seeds turning grey and looking like they are expanding and slimy. This is a good thing. They are supposed to look like that.

Keep the seeds moist, but don’t drown them.  After a couple or three days you will see little sprouts sticking out of the grey slimy seed balls.  At this point, mist them twice a day or as needed to keep a nice sheen of moisture on them.

Post Sprout – 3 – 7 days

During this time you should mist until the leaves spread out.  Once the leaves are out (the initial pair that is), stop misting and water gently and slowly at the base.  This will discourage mold growth on the plants themselves. Water a small amount twice daily for best results.  Don’t over-water, but at the same time, keep the medium moist. It will be a delicate balance between moist and soaked.  

Seedling – 7 – 14 days

You can cut the watering down to once a day during this phase of the microgreen.   Just make sure you aren’t letting the soil dry out too much or you’ll see the basil curl and die like those shown in the accompanying photo.

Purple Basil sprouts that have dried out are shown in this file photo.

Basil Ideal Temperature Range

The optimum temperature for this plant is as follows.

Germination

  • 76 – 82 degrees Fahrenheit
  • 24.4 – 27.7 degrees Celsius

Sprouting/Microgreen

  • 70 – 82 degrees Fahrenheit
  • 21.1 – 27.7 degrees Celsius

Full Plant Growth

Daytime
  • 70 – 82 degrees Fahrenheit
  • 21.1 – 27.7 degrees Celsius
Nighttime
  • 60 – 70 degrees Fahrenheit
  • 15.5 – 21.1 degrees Celsius

These are the optimum temperatures I have found for best results in growing this plant.  The temperature is not super critical but the plant really starts to do poorly when the temperature hits lows of 50 degrees Fahrenheit or 10 degrees Celsius.  That’s danger zone and could end your basil. Basil likes it warm. But, don’t we all?

Pests/Diseases

The two main issues I’ve faced with Purple Basil Microgreens are mold and flies.  Now, I am using organic soil, so a certain amount of mold and sometimes small flies is to be expected.  The flies I have encountered are tiny, little black looking flies that seem to do no harm, they are just annoying.  

How To Get Rid Of Flies In Purple Basil Microgreens

When you have moist soil, and if you aren’t bottom watering, then you can get these annoying little flies called Fungus Gnats.  They are fairly harmless but they are really annoying. There are a few ways to get rid of these but I have good luck with a chemical trap.

One of the most effective ways I’ve found of getting rid of flies in my microgreens is by concocting a vinegar, soap and honey solution.  I just take a glass and add about an inch of apple vinegar. Then a few drops of dish soap and a couple of drips of honey. Mix the solution and put a layer of plastic wrap over the glass.  Poke some holes in the plastic wrap and leave it out by your plants. Adult flies will get trapped and drown. Muahahaha

How To Control Mold With Microgreens

Mold growth in your microgreen flats is typically controlled nicely with proper watering and air movement management. Mold really likes two things, moisture and semi-stagnant air.  Why semi-stagnant? That’s because mold doesn’t like drying out, but wants enough air movement for its spores to spread.  

Solution: water from the bottom.  Use a pot that has holes in the bottom, put the pot in a tray, and water that tray.  The water will seep up into the pot. This keeps the top inch or two of soil relatively dry.  Bugs don’t like a desert. They like moist soil. You can also add a small fan. This will not only blow away any small flying pests but also strengthen your plant stalks.  Be careful though, too much and it can dry out your plant really fast.

Cool Tip: Add a layer of sand and/or small pebbles to the top of the pot, on top of the soil.  This adds a decorative look but also allows water to drain down quickly, keeping the top of the pot dry.  This helps prevent any kind of surface soil breeding bugs from growing. Add a bit of colored sand and let your imagination run wild.  Could be a new trend?

Other Pests And Problems Purple Basil Can Face

If you are growing outdoors, watch out for Powdery Mildew.  Because basil likes a warm environment with moist soil, this means that in places like North America, it can fall prey to powdery mildew which likes warm, moist conditions.  Again, the sand trick can help, as well as bottom watering. If you plant this in a bed, a raised bed with good drainage is preferred. But, you will need to water frequently.  An automated watering system can really be helpful in this situation. Or, utilize a ground watering technique like burying a 1 inch plastic or pvc pipe with holes drilled in the sides.  You can pour the water down the buried pipe to water the ground under the surface and prevent surface molds from spreading.

One of the other common pests you can get on the purple basil, when growing outdoors, is aphids.  I’ll get into those pesky pests in another article.

Harvesting And Storage

Harvesting – Microgreen

Farmer Jer is holding some purple basil microgreen sprouts ready to harvest at 2.5 inches tall, in this file photo.
Farmer Jer holding some ready to harvest purple basil microgreen sprouts.

The optimum harvesting time for a purple basil microgreen is approximately 14 days after starting the seeds.  The plant should be about 2 – 3 inches or 5 – 7.5 cm tall

Microgreen Yield

One 10 inch by 20 inch (25.4 cm by 50.8 cm) tray, using 1 oz of seed, can be harvested every 14 days to produce about 4 cups of sprout microgreens.

Harvesting – Full Growth Plant

It’s best not to harvest anything until the plant is at least 6-8 inches in height if you intent to grow a full size plant.  The leaves are best harvested in the morning for their richest value. Pick leaves off the plant regularly to encourage the plant to continue to grow more leaves.  

Full Growth Yield

One full grown plant can produce up to ½ cup of basil leaves per week.

Storage

Microgreens

Store freshly harvested microgreens in a semi-breathable container in the fridge.  They can typically be kept for up to about 5 to 7 days in the refrigerator if kept at the right temperature and humidity.  I put a small freshly shaved carrot in a container with a loosely fitting lid. The carrot seems to shed just the right humidity to keep the microgreens good for a week in the fridge.

Full Size Leaves

The best way to store fresh basil leaves is to place them into a freezer bag and squish out as much of the air in the bag as possible.  Then place them in the freezer. You can then keep them for up to a year and they will maintain a decent freshness.

Seeds

Keep the seeds in a cool, dry place.  It is best practise to keep them in a dark place as well.  Sunlight can damage and kill a dried seed so it is best to keep them in a sealed container that is dark or away from bright sources of light.  Maintaining the correct humidity is important for the longevity of the seeds.  

History

Basil has been around for some time.  And there are some very strange accounts of its use.  One such account, an anecdote attributed to Joseph Pitton de Tournefort (June 5th, 1656 – December 28th, 1708) says something about the use of the plant”

It is said a Gentleman of Sienna was ‘so taken with the Smell of Basil’, that he snorted it.  That’s right, you read that right. He snorted the crushed up leaves because he had the crazy notion to do so due to his love for the smell.  Unfortunately for him, it drove him mad and he died.

Surgeons performed an autopsy on the deceased man and found something peculiar.   They found a nest of scorpions inside his brain. They attributed the scorpion nest to the snorting of Basil. In short, making Basil an evil herb by the account of this anecdotal tale.  

Contrary Beliefs

Unlike our scorpion tale above, in another part of the world Basil is almost treated as a king.  For instance, in India the herb is attributed to the gods Vishnu and Krishna. In fact, there was a tradition of laying a branch of the herb on the chest of the dead.  It was believed that this would help to protect them from evil and allow them to pass safely into the afterlife. Not quite the scorpion in the brain sort of tale, now is it?

Purple Basil Plant Uses

Aesthetic

Basil is a pleasant, albeit common looking plant.  Some of the basil varieties can be kept for their appearance, but the usefulness of the plant always outweighs its value for aesthetics.  The purple basil is, in my opinion, one of the more beautiful of the basils. The purple leaves add an attractive look to any herb garden.

Culinary

Everyone who cooks knows about basil.  Sweet basil is one of the most commonly found kitchen herbs in North America and throughout many other parts of the world.   Known for its wonderful flavour it adds to create sauces like pesto sauce, basil is a staple in any sauce makers kitchen. From Italian to Thai, From Canadian to Mediterranean, basil has made its way into tomato sauces and into our hearts.

Basil leaves are the most commonly used part of the plant.  The leaves are typically dried and crushed. The application of crushed basil is typically done via a medium to large dispensing hole herb shaker.  The leaves are usually crushed via a mortar and pestle or an herb grinder. Either works well. The traditional being the mortar and pestle of course.

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Medicinal

Basil is a member of the mint family.  And what is the mint family known for? Helping with digestion, that’s what.  If you ever have an upset stomach, a basil tea can help. It has a bit of a bite to it, but I find a mild basil tea with a touch of honey does the trick to help with tummy upsets.  It also helps with gas and cramps associated with gas.

The tea which is non-toxic to humans has also been administered for anxiety and nervousness.  The tea apparently has a mildly sedating effect which explains the use. However, I have not personally felt a sedative effect when I have had this tea.  I think this may be due to people having an upset stomach after dinner, which is in the evening. Then they have a tea, they feel better and are thus able to sleep.  After an issue with indigestion, most humans get sleepy after the effects of indigestion are abated. At least, that’s how it seems to work for me personally anyway.

Cosmetic

Believe it or not but basil apparently brings great shine and lustre to hair. In fact, the herb is widely cultivated for use in lotions, perfumes and toiletries due to its invigorating scent.  Want to try it? Add some basil paste to a rosemary rinse if you are a brunette or a chamomile rinse if you are a blonde. You will need to rinse thoroughly but it will add lustre to your hair.  Or so it is written…

Did You Know That? 

Basil is believed to have originally been cultivated in India as an offering to deities but was not used in culinary.  It wasn’t until basil was exported to other areas that it began to be used by other cultures as a means of flavoring food.

Bibliography

  1. https://sproutpeople.org/growing-basil-micro-greens/
  2. http://www.farmgirlfare.com/2008/06/purple-basil-pesto-easiest-white-bean.html
  3. https://university.upstartfarmers.com/blog/how-to-grow-microgreens-beginners-guide
  4. https://en.wikipedia.org/wiki/Basil
  5. https://en.wikipedia.org/wiki/Joseph_Pitton_de_Tournefort
  6. https://www.hortidaily.com/article/6032544/not-so-purple-basil/
  7. https://en.wikipedia.org/wiki/Spice_trade
  8. https://www.almanac.com/plant/basil
  9. Rodales Illustrated Encyclopedia of Herbs, Authors: Anna Carr, Catherine Cassidy, Ellen Cohen, Alice Decenzo, Marjorie Hunt, Judith Benn Hurley, William H. Hylton, Claire Kowalchik, Susan Milius, Kim Wilson., 1987, United States Of America, Rodale Press, Inc. Pages 22-26, 100, 101, 102, 212, 213, 238, 305

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