How to: Grow Cilantro Hydroponically

By: Chris | Last Updated: December 8, 2020

The use of cilantro dates back 8,000 years ago to Israel, where it was found in ancient caves. King Tut even had cilantro seeds scattered in his tomb. It would seem our ancient ancestors enjoyed food with a little kick! 

Modern food enthusiasts find cilantro in Southwestern dishes, and in the cuisine of the Middle East and North Africa especially. Be assured of one fact about cilantro: the spicy herb is no fence sitter. People either love it or hate it. 

Interestingly, cilantro is named differently in different parts of the world. Generally, in North America, the leaves of the plant are called cilantro, while the seeds are coriander. Both herbs have different tastes, different health benefits, and different functions. 

Most Suitable Hydroponic Method: Any
Best Grow Medium: Rockwool
Time to Germinate: 7-10 days
Time to Maturity: 50-55 days
Ready to Harvest: 40-48 days
Optimal pH Range: 5.5-6.4
Optimal Nutrient Mix: CaNO3, MgSO4, and NPK
EC Range (Nutrient Strength): 1.2-1.8
Optimal Temperature: 45-75°F
Growing Difficulty: Easy

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How to Germinate Cilantro

Cilantro germinates quickly and easily. It will be ready to transplant into your hydroponic system within 7-10 days.

If you plan to germinate the seeds in rockwool, be sure to pH balance it prior to planting the seeds! The entire cube needs to be damp when you initially place the seeds in it. Placing the rockwool cubes on a growing tray will allow you to bottom water the seeds. To do this, simply add about 1/8″ of water to the bottom of the tray. The rockwool will wick the water up to the seeds without oversaturating them.

The paper towel seed germination method also works really well for cilantro. I prefer it because it doesn’t waste seeds or rockwool cubes if seeds fail to germinate.

Regardless of the germination method you use, cilantro will be ready to transplant into your system once it reaches a height of 2 inches.

Hydroponic Cilantro Fact Sheet

Growing Cilantro Hydroponically

Learning how to grow cilantro hydroponically is not difficult, as long as you follow a few quick tips. Cilantro is very low maintenance, but its broad leafy overlays do tend to take up a lot of room. 

Once in the hydroponic system, the cilantro will grow rapidly. Space cilantro seedlings 8-10 inches apart to encourage lateral growth. 

12 hours of light from a T5 fluorescent light in plenty for growing cilantro.

Since the plant is prone to bolt in the summer, grow room temperatures should be kept at or below 75°F. The cooler you can keep the plant, the longer it will produce before bolting.

Once a plant starts to bolt, there is no going back. Cutting the flowering stem will not stop the leaves’ bittering, so do your best to keep the plant from bolting early. Keep reading to find out what happens if the plant does bolt!

Fresh Hydroponic Cilantro

Best Hydroponic Cilantro Varieties

Any type of cilantro will spread its leafy goodness in your hydroponic garden, but to get the best results you want to select a bolt resistant or slow-bolting variety. Two of my favorite varieties are Calypso Cilantro and Leisure Cilantro.

Calypso Cilantro
Calypso cilantro is arguably the slowest bolting variety available. It will resist bolting for up to 3 weeks longer than Santo varieties. Calypso is a slightly slower growing variety, as evidenced by its later bolt, but still produced large bushy plants.

Leisure Cilantro
Leisure cilantro is another great variety that’s slow to bolt. It will bolt slightly sooner than Calypso. The Leisure variety was developed specifically for partial, cut and come again harvesting. This variety can reach heights of up to 24 inches, almost twice the height of Calypso. Keep that in mind if you have vertical growing limitations.

Both varieties are excellent choices, providing the zesty aromatic flavor that makes cilantro so unique.

How to Harvest Cilantro

Cilantro will be ready to harvest about 50 days after planting, or when the plant reaches 5 to 6 inches tall. Cilantro can be harvested in full or partially harvested to prolong the life and production of the plant. Unless you are a commercial grower, partially harvesting cilantro normally makes the most sense.

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09/24/2021 12:08 am GMT

How to Harvest Cilantro without Killing the Plant

Once the cilantro plant has reached around 6 inches tall, it can be harvested safely without killing the plant. To do this, cut off the top 1/3 of the plant at the stem. Cutting with sharp scissors will make a clean cut without disturbing the root system of the plant.

This method of harvesting plays two roles. First, it provides you with a harvest of fresh cilantro leaves. Second, it prunes the cilantro plant, which encourages lateral growth and increased plant development.

Alternatively, you can also harvest smaller amounts of cilantro for immediate use in recipes. This can be done by cutting the top third of a few stems or by pinching off leaves. Harvesting in this method provides you with super fresh, aromatic cilantro perfect for cooking.

How to Store Harvested Cilantro

Harvested cilantro can be refrigerated, frozen, or dried for long-term storage.

To refrigerate cilantro, fill the bottom of a large glass with water. Place the cut end of the stems into the glass so they can absorb water. Place a large plastic sandwich bag over the cilantro and glass. Stick this contraption in the refrigerator, and change the water every couple of days to keep cilantro fresh for 2-4 weeks.

Freezing cilantro can be done in a couple of different ways. Put chopped cilantro leaves, or leaves and stems depending on your dining preference, in a sealable sandwich bag. Place the sandwich bag in the freezer.

Alternatively, you can put chopped cilantro into an ice tray, fill the ice tray with water and place it in the freezer. Cilantro frozen by either method will be usable for up to 2 months.

Preheat oven to 300°F. Remove leaves from stem and place leaves on a baking sheet with parchment or non-stick paper. Spread leaves across the baking sheet in a single layer. Bake in the oven for 30 minutes. Carefully take the baking sheet out of the oven and let it cool. Crumble the cilantro leaves and put them in an air-tight container. Store them wherever you store your herbs and spices.

Dried cilantro won’t have the same zesty pop that it did when it was fresh, but it’s still a great way to preserve the herb for long-term use.

Check out CiCi Li’s tips for storing Cilantro.

It’s Magic! Turn Cilantro into Coriander

So, how do you turn cilantro into coriander? It’s simple. Let the cilantro bolt and go to seed. Coriander seeds are actually what you plant to grow hydroponic cilantro. I know, not the best magic trick in the book, but it’s still pretty cool!

If it’s stayed cool and happy, cilantro will begin to bolt and go to seed at around the 90-100 day mark. If you want your plant to bolt sooner, to harvest coriander seed, turn up the heat. A hot environment with high light intensity can encourage the plant to bolt much earlier than normal.

Flowering Hydroponic Cilantro with Coriander Seeds

The plant will produce petite white and purple flowers. As the flower fade and fall off, small green seeds will emerge. The green seeds are edible, and will have a much more pronounced flavor. Green coriander seeds have a short shelf-life, and are not commonly available in grocery or herb store.

If you prefer to harvest the seed either for planting or grinding, allow the seeds to continue to develop until they brown. Once most of the seeds are brown, cut the stalk and place it in a paper bag with the cut stem pointing out of the bag. Tie the bag around the stem, and hang it to dry in a warm area.

When the seeds are fully dried they will drop off the plant, into the bottom of the paper bag. At this point shake the bag and seed to dislodge all the seeds. Separate the chaff (stems, and other plant parts) from the seeds, and grind to your hearts content. Store coriander in an air-tight container to maintain its citrusy and nutty flavor.

Cilantro Health Benefits & Taste

To those who enjoy it, cilantro has a fragrant, citrusy flavor and is best eaten fresh.

Some people have a genetic predisposition to experience cilantro as a soapy taste. Obviously, these people would find the taste abhorrent. Who wants to eat soap?

No matter what you think it tastes like, this leafy herb, related to the carrot family, offers many health benefits, beyond the punch of flavor that it brings to many dishes. 

Cilantro offers a nice amount of the recommended daily amounts of Vitamins C and A, along with an outlandish amount of Vitamin K, constituting 38% of your recommended daily allowance.

Beyond the nutrients cilantro can supply, it is also an herb with medicinal qualities. Cilantro is known to have anti-inflammatory properties and can assist with several conditions, including pain, skin ailments, and fungal diseases such as thrush.

Chris Cook started Happy Hydro Farm to share his passion for hydroponic gardening! Growing your own food is incredibly rewarding both physically and mentally. His mantra - "Take excellent care of your plants, and your plants will take excellent care of you."