Growing cilantro from seed, either to grow out in your garden, place in containers, or as microgreens can be at times a bit frustrating.
Even for experienced gardeners or growers.
This article will explore the first trick that many growers, gardeners, and garden bloggers talk about when planting cilantro seed.
That trick is soaking cilantro seed before sowing it either in the ground or tray.
I don't want to say every article, blog, or book you read on growing cilantro from seed says to pre-soak the seed. But the vast majority suggest soaking the seed 8- to 24-hours before planting.
There are a couple other tricks we use to improve cilantro germination rates and yield and you can read how we grow cilantro in this article. This post will concentrate on whether you should soak or not soak cilantro seed before planting.
Growing Cilantro From Seed
As mentioned, the consensus among growers that publish on the internet or in books is that cilantro seeds will germinate better and faster if they are soaked for several hours before you plant them.
However, nowhere did we see a test or comparison between a tray of dry sown seed and pre-soaked cilantro seeds.
We're not saying that all of the growers haven't tested or experimented with their cilantro seeds. But some visual proof would make us feel better about taking the extra time and bother of soaking seeds.
After all, we've shown that soaking seeds, even those varieties that growers suggest should be soaked, didn't make much of a difference in germination rates or microgreen yield.
Test: No Soaking verse Soaking Cilantro Seeds
The test is simple and easy to set up.
We measured out two equal masses (3.5-grams) of cilantro seeds. One set of seed was set aside. To the other set, room temperature, non-chlorinated water was poured over the seeds and allowed to soak for about 24-hours.
Day Zero - Seed Sowing
Both sets of seed are sown onto a professional soil mix (coconut coir based) in a 38 square-inch tray.
A shaker is used to spread the dry seeds on one tray evenly. The pre-soaked seeds are rinsed with fresh water and placed on the second tray. Because the wet seeds have a tendency to stick together, they need to be gently spread-out using fingers.
Below is the photo of the cilantro seeds after sowing.
A spray bottle is used to wet to seeds and soil before the trays are covered and blacked-out from light. Weights are added to the top of the trays and placed on a seed heat mat for four days before they're looked at again.
Day 4 - Cilantro Germination
On the fourth day, the covers are removed to check on the cilantro seeds. To see the images better, you can click on any image in this article to make it bigger.
As you can see, the pre-soaked cilantro seeds have split open and are setting roots while the dry sown seeds haven't progressed as fast.
Remember, the only difference between the seeds and trays is that the seeds on the right were soaked for 24-hours. After that, both sets of seeds and trays have been handled the same way.
It appears that pre-soaked cilantro seeds germinate quicker than dry sown seeds.
But, does, or will it make any difference as the plants grow.
At this stage, both trays were again covered, blacked-out, and a weight is added to the top of the covers and placed back on the seed heating mat.
Day 8 - Removing the Covers from the Cilantro Seeds
On day eight the cilantro seedlings are ready to be uncovered and placed under light.
Let's see how they're doing.
The tray on the right (pre-soaked seed) has more growth and a better germination rate than the dry sown seeds. Remember, the trays were covered and weighed down. Neither tray has been under lights as of yet.
For some reason, the plants to the back of the trays have grown a bit bigger and lifted the covers off the surface. Maybe the weights weren't centered very well.
So far, the pre-soaked seeds are growing faster than the dry sown seeds.
Day 9 - First Day Under the Lights
It's incredible how quickly microgreens perk up after one day under the lights. They come out of the stack and dark a whitish-yellow, all bent over and squished and within a day they are much greener and standing upright.
Cilantro is no different. Below is a photo showing how quickly the plants perk up.
You can see that the pre-soaked seeds (labeled "wet") are slightly more vigorous and appear to have better germination.
Day 12 - Real Growth on the Cilantro
A few days under the lights do wonders for microgreens. On day 12 the cilantro microgreens are about an inch tall, and the cotyledons are filling out the tray.
As a side note, when the microgreens need watering both trays are watered at the same time and with equal volumes of water. Both trays are under the same LED lights as well.
Also, notice that the number of seed husks on both trays of microgreens is about the same. As with the beet test, soaking the seeds didn't cause more of the husks or hulls to fall off.
The cilantro to the right (pre-soaked seed) has filled the tray out. The pre-soaked seed did germinate quicker and at first, seemed to have a better germination rate.
However, the dry sown seed does have a similar germination rate, but the seeds germinated over a more extended period. The same number of seeds germinated, they only took longer to sprout.
Day 15 - Pre-soaked Cilantro Seed Has Lost Its Advantage
As you'll see in the photo below, the cilantro grown from the dry sown seed has caught up to the plants grown from the pre-soaked seed.
Soaked cilantro seed does germinate quicker and within a shorter period than non-soaked seed. The plants also grow faster during the early stages of growth.
But over the long haul, it doesn't appear to make much of a difference on the overall germination rate and growth rate
The cilantro microgreens in both the dry sown tray (left most trays) and the pre-soaked tray are very similar in size.
Day 17 - First Possible Harvest Day
Cilantro is one of the great microgreens that have a long harvest period. Between day 15 and 20 you can begin to harvest cilantro microgreens. You can also begin to transplant cilantro from your seeding racks or double cups into your indoor/outdoor containers or into the garden.
The first true leaves are starting to form at this point. However, you can continue to allow your microgreens to grow and harvest as you need them.
In fact, it's best to wait for longer than 17 days to harvest. The flavor will be better as the cilantro matures. As you can read in How to Grow Cilantro Microgreens it takes up to three weeks for the microgreens to mature.
Below are the two cilantro trays on day 17.
I believe it would be difficult to pick out which tray of cilantro is which. They are very similar in size, plant density, and health.
Ultimate Decider - Total Harvest Mass
We can look at the cilantro microgreen trays and try to decide which seeding method produced the highest yield or we can harvest the greens from each tray and weigh the cut cilantro microgreens.
What Was the Result?
The harvestable mass of each tray was within one gram of each other. Both trays of microgreens harvested around 40-grams of cilantro.
So, in the end, it was a wash.
When Growing Cilantro From Seed Do You Soak or Not Soak the Seed?
You can do either!
We're glad we set-up this test. We were pre-soaking our seed and suggesting to our customers that they do the same.
I mean, most growers are soaking their seed before sowing it, so why wouldn't we?
But soaking the seed is a pain in the butt. Besides that fact it's another step, and takes a bit of forethought, spreading the wet seed is more time consuming and not fun.
Using the shaker bottle to spread the cilantro seed is much easier and faster.
Better Initial Germination Rate & Growth Rate
The pre-soaked seed had a better initial germination rate and faster early growth.
However, after 15-days the dry sown cilantro caught up to the faster starting pre-soaked cilantro seed.
We believe this will be the case whether you are growing cilantro from seed for microgreens, growing cilantro seedlings for transplanting or sowing the seed directly into containers or the garden.
From now on we will dry sow our cilantro seeds.
Have a Question?
If you have any questions about the information in this post or microgreens, in general, please leave a comment below or reach out to me using the Ask a Question page.
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