How to grow cilantro indoors

Many have witnessed the often polarizing effects of the seemingly innocent herb, cilantro. Revered by some as the holy grail of garnishes, a portion of the population disagrees, relating it to the punishment of washing ones mouth out with soap.

But for those of you on Team Cilantro and looking to grow herbs indoors, you’re in luck! Cilantro is not recommended for multiple harvests, but for indoor gardeners with intermediate indoor herb experience, growing a continuous succession is possible all year long. By creating an indoor environment that is warm, dry, and airy, many indoor gardeners have a successful crop.

History and application of cilantro

For such a controversial taste, cultures across the globe have embraced cilantro and coriander as their own for centuries. The earliest recorded coriander was found in Israel and dates back 6,000 B.C.E (2). Romans loved to trade it, and King Tut’s sarcophagus was adorned with coriander seeds to enhance his passage from human to deity (3). Pinpointing the origin is difficult, but spanning across cultural cuisines, the herb is almost always used raw.

Coriander vs. Cilantro

Vastly different in taste and application, cilantro and coriander receive separate but equal appreciation. While cilantro is the bright green plant with textured leaves, the seed is used to produce the popular spice coriander (1).

The aromatic fruit of the Coriandrum sativum, or the coriander seeds, are ⅕” in diameter and can be used in recipes, whole or crushed (4). Its flavor is earthy, spicy and acidic, and you’ll find coriander prominently flavoring pickles in Middle Eastern or Asian cuisines. Europe and the Americas also hold an affinity for coriander, from the use in Belgian wheat beer since the Middle Ages, to shining in many Mexican dishes and referred to as semilla de cilantro in Spanish.

Related to parsley, dill, carrots and parsnips, in most cuisine, cilantro is used fresh to maintain the complex, acidic, pungent flavor. All varieties will do well in an indoor environment. You’ll find large amounts of cilantro in Indian, Middle Eastern, Asian, South American, and North American cuisine.

Medicinal properties of cilantro

Because the use of cilantro and coriander are ancient and widespread, there are many claims to its health benefits and healing properties. Scientific research shows that the antioxidant nature of cilantro is the most supported, with its ability to suppress oxidation stress and reduce radical scavengers (5).

Studies are also developing with cilantro’s ability to remove heavy metals. Rats exposed to lead for four weeks, and then treated with coriander concentrate for seven days, tested lower for lead compared to the rats who were not treated with coriander (5).

A bunch of fresh cilantro cut in half

Try some fresh cut cilantro on tacos or a BBQ chicken pizza to give an extra kick of flavor! Image: Jamie

Why cilantro is good to grow in containers

With its large seeds, planting cilantro in containers is easy. Cilantro is forgiving when it comes to seed spacing, so you have creative freedom to use containers you already have. Cilantro can reach about one foot before it produces seeds, but it’s recommended to begin harvesting once it reaches 6 inches (6).

Cilantro prefers cool climates

When the weather rises above 85 degrees fahrenheit, the cilantro plant is triggered to go into reproductive mode. This process is referred to as bolting; when the leaves become thin, the flavor is lost, and large umbrella-like structures form flowers and seed pods.

Growing conditions and basic care

Because it can survive in zones 3-11 on the USDA’s plant hardiness map, cilantro is a great herb to start indoors and move outside when the weather warms up.

The USDA divides North America into 11 separate planting zones, helping gardeners and farmers understand when they can plant their desired crops outside. This general understanding can be helpful when migrating plants from indoors to outdoors.

Cilantro prefers full sun, at least six hours per day. You will also find cilantro extremely happy when it has well drained soil and lives in temperatures 50-80 degrees fahrenheit. Directing seeding is recommended, as cilantro forms a taproot and does not enjoy being transplanted. Sow seeds ¼” deep and for a steady succession of fresh cilantro, plant every 2-3 weeks. Propagating is not recommended, but if you decide to grow indoors using transplants, it is recommended setting seedlings 8 inches apart.

Light

If you aim to grow cilantro in December in the northern region of the United States, it is recommended that you use grow lights. Depending on your latitude, even a south facing window may not provide enough sun during the winter.

A simple LED, 45 watt grow light can provide the right amount of light your baby cilantro needs. Lights should be suspended just above the surface of the plant; this prevents the cilantro seedlings from becoming “leggy” and straining to reach the light source. As the plant grows, the light should be raised.

Temperature

Cilantro seeds require 55-68 degrees to germinate, and indoors it can take 7-14 days for little sprouts to appear in your pot. Cilantro can survive a light frost, but if you are growing in your windowsill, make sure your placement is safe from extremely cold drafts.

Some air circulation is good for cilantro, especially when growing microgreens. Cilantro is susceptible to damping off, a fungus that first appears as white mold and then shrivels the stems until the seedlings die (7). Prevent this with good air circulation or a small fan.

Water

Well-drained soil is the key to caring for cilantro, as well as thorough watering, compared to frequent watering. Only water when the top 15% of the soil is dry, as dampness will create disease, especially with high seed density.

Remember: plants crave moisture, not water, and underwatering is always better than overwatering.

A spray bottle is the ideal method of irrigation when germinating seeds and watering seedlings. A cheap alternative can be a plastic water bottle with small holes punched into the tightened lid. If the soil is so dry that it has difficulty absorbing, be patient for it to saturate before dosing with water again. Gradually water your cilantro until the soil absorbs the water and it drains out the bottom of your container.

Unchlorinated water is best, and you can typically take tap water and let it sit for 24 hours so the chlorine evaporates. Unglazed, terra cotta pots are best to help soil remain moist, while also being impermeable to light so algae does not grow.

Soil and fertilizer

There is potting soil mixes specifically for indoor edible plants, but if you cannot find it at your local home improvement store, look for mixes that include peat moss, coir, perlite or mix that includes fertilizers.

Because the cilantro plant will have a finite supply of space, and therefore nutrients, it is important to keep your container fertilized. Diluted fish emulsion is a great option for adding nutrients into the soil, but use a reduced amount as recommended by the size of your container; too much fertilizer can be just as detrimental!

Harvesting

Always use clean scissors and clean hands when harvesting cilantro, and the rule of thumb is harvest ⅓ of the plant per week. Cilantro is a short annual and is typically enjoyed for 8-10 weeks, and it is not a “cut-and-come-again” type of herb.

If you want an endless supply, direct sow your seeds every 2-3 weeks, and pinch off the tops of cilantro to extend the lifespan of the plant. Harvest for the full-grown herb is around 45 days, or after 20 days if you want to harvest as a microgreen.

Cilantro microgreens

If this is your first time exploring microgreens, this is a method of densely seeding on a shallow, wide tray, about 10” x 21” and harvesting after the first true leaves have appeared. Especially cilantro microgreens, these tiny plants pack a punch and are delicious and nutritious on chili and tacos.

  1. For each shallow tray, fill with potting soil and spread 26 grams of seed over the surface of the tray. For rates and information on seeding, please see this chart from Johnny’s Selected Seeds.
  2. Do not cover the seeds with soil, and stack a tray on top to compress the seeds. Use a weight, like a hardcover book inside the top tray to provide compression.
  3. After 24 hours, use a mister, spray bottle, or fine droplet watering hose, and lightly saturate the soil with water. You do not want to flood the tray or the seeds will displace. Water once a day, and remember to check the top level of moisture; always underwater instead of overwater.
  4. It is especially crucial to have good airflow when growing microgreens because the seeds are so densely seeded. Prevent fungus growth and damping off with good air circulation or a small fan.
  5. You should harvest cilantro after the first true leaves appear, when the microgreens resemble the scalloped leaf pattern that cilantro is known for, typically 20 days after seeding.

Although experimenting with cilantro is recommended prior to growing microgreens, with proper growing conditions, good air circulation, perfect seed density, and light, you can have a tasty garnish for every meal. An added bonus: after harvesting, you will not mind having a few seeds in your garnish; they are tasty coriander after all!

Conclusion

Growing herbs indoors can be a great way to have fresh, organic food all year long, and cilantro is one of the easier herbs to master. With its range in culinary applications, you and your family will enjoy caring for your plants and growing your green thumb.

Resources:

  1. http://gardeningsolutions.ifas.ufl.edu/plants/edibles/vegetables/cilantro.html
  2. https://www.jpost.com/Arts-and-Culture/Cilantro-the-biblical-herb
  3. https://books.google.com/books?id=5eZOITEqDkQC&pg=PA62&lpg=PA62&dq=romans+trading+coriander&source=bl&ots=uGbJ7ZHtrM&sig=ACfU3U2eOv8947rlXReDL8OOGEEI5w_6xA&hl=en&sa=X&ved=2ahUKEwjzufCfz_HgAhVk94MKHTl3CEIQ6AEwCHoECAIQAQ#v=onepage&q=romans%20trading%20coriander&f=false
  4. http://botanical.com/botanical/mgmh/c/corian99.html#par
  5. https://download.lww.com/wolterskluwer_vitalstream_com/PermaLink/NT/A/NT_51_3_2016_03_31_SINGLETARY_15048_SDC1.pdf
  6. https://www.bhg.com/gardening/plant-dictionary/herb/cilantro/
  7. https://www.smartgardener.com/plants/608-cilantro-coriander-cilantro/diseases/797-damping-off
  8. https://journals.lww.com/nutritiontodayonline/fulltext/2016/05000/Coriander___Overview_of_Potential_Health_Benefits.8.aspx

Feature image: Salvation Army USA West