Growing Cilantro (Coriander) & how to germinate Coriander seeds

I grow a lot of coriander. Or cilantro as you may prefer to call it. But to germinate coriander seeds can take time. And it can be challenging.

It is quite normal to wait 2-3 weeks and sometimes longer for the seeds to germinate and sprout seed leaves.

And before the seeds germinate you simply do not know if you have a healthy and productive seed. And it does not help that the germination rate is far from a perfect 100%.

These are all reasons why I am a classic overseeder. I know I use too many seeds per starter pot but I prefer to increase my chances and will deal with the risk of overcrowding later.

Transplanting Coriander and Dealing with overcrowding

Overcrowding means a more complicated process when it becomes time to transplant the seedlings.

And coriander is known to be difficult to transplant due to its delicate taproot.

Yet, I continue to oversow coriander seeds. And I have my way of dealing with the challenge of transplanting coriander.

When I transplant the seedling I do not separate them to be replanted one by one.

Instead I transplant bunches of seedlings together and thin out the plants later when and if needed by harvesting young leaves for salads, dressings and cooking.

I make no promises but maybe I could stop oversowing if I could find a better and faster way to germinate coriander seeds .

Looking for a better way to germinate Coriander seeds

I have always planted coriander seeds straight from the seed packet. And it has overall worked well.

But could there be a better way to germinate coriander seeds to shorten the time it takes to identify bad seeds?

I decided to test three different methods of preparing the coriander seeds before planting. 

The plan is to see if germination time will differ between the three methods.

  1. Coriander seeds straight from the seed packet
  2. Soaking coriander seeds for 48 hours before planting
  3. Expose the coriander seeds by crushing the surrounding husk

I will use a 50/50 blend of cactus soil mix and regular potting soil and use plastic recyclable starter pots (7 centimeter/ 3 inches).

Progress is checked and reported on a weekly basis. I will pick the winner when the first set of seedlings are large enough to be transplanted to a larger pot.

Eight (8) seeds are planted in each pot and I need at least two healthy seedlings from any given pot to call a winner.

Testing 3 ways to germinate Coriander seeds

Start (Day 0): Planting 3 sets of Coriander seeds

Having prepared the pots I planted the 3 sets of 8 seeds in separate pots marked with labels.

I put a thin layer of vermiculite on top of the soil after the seeds were planted to help retain moisture.

I used the same number of seeds (8) for each pot. The soaked seeds and the seeds straight from the seed packet were placed in different holes around the pot.

The crushed seeds were sprinkled across the soil and then covered with a layer of potting soil and a thin layer of vermiculite.

Week 1 (Day 1-7): Crushed Coriander seeds taking the lead

I have to say I am surprised to have seed leaves (first leaves) within as little as one week of planting the seeds..

You may have your favorite but so far it seems that crushing the seeds is the most effective way to germinate the seeds faster.

Crushed coriander seeds germinating already week 1
Two sets of first leaves from crushed seeds already week 1.

Today, exactly one week after planting the crushed coriander seeds I can see two sets of first leaves.

And the larger of the two germinated already after 4 days!

It would however be premature to pick the winner already today. I need at least 2 strong seedlings with true leaves that will cope with being transplanted.

It will be interesting to see if crushing the seed will have an effect on how quick the seedling will grow.

And will the seedling grow as big from a crushed seed?

Could it be that the other methods catch up?

I am genuinely interested to find out. Stay tuned.

Week 2 (Day 8-14): Soaked & natural coriander seeds lagging Behind

The short answer is that the crushed coriander seeds still show the best result – by far.

Crushed coriander seeds with true leaves in less than 2 weeks.
Crushed coriander seeds sprouting true leaves in less than 2 weeks.

Soaking the seeds and planting the seeds straight from the seed packet is lagging behind. 

I do see first leaves from the coriander seeds that were soaked for 48 hours before planting. 

The seeds planted straight from the packet show no signs of sprouting first leaves.

Still – as you can see from the photo – the seedlings from the crushed seeds are doing really well. There are true leaves on 3 out of 8 seeds and first leaves from 2 more seeds.

This gives us 5 out of 8 seeds germinating within 14 days of planting.

As a side note I have planted new batches of coriander seeds using the same principle – soaked seeds, crushed seeds and seeds straight from the packet.

If I can replicate the result with this second batch I would be ready to call a winner already next week.

Time will tell. Stay tuned.

Week 3: (Day 15-21): Will Crushed coriander seeds still be ahead

Crushed coriander seeds outperforming soaked and natural seeds
Crushed coriander seeds outperforming the soaked seeds in second place.

I can honestly say that I expected this to be a closer race.

But already now I feel comfortable stating that crushed coriander seeds will germinate faster.

I saw true leaves from the crushed seeds already last week (week 2). I am still not seeing trues leaves from the soaked or natural coriander seeds.

And yes, I have grown several test pots to confirm the findings and they still hold true.

As a side note, I can almost get soaked seeds to germinate as fast as crushed seeds. But not every time. 

And soaking seeds is more work as we have to wait 48 hours before we can plant the seeds.

Not a big deal but still not as straightforward as gently crushing the seeds and planting them straight away.

Crushing soaked coriander seeds is my next project. Will they germinate even faster? I will get back to you when I have an update.

Meet the author: Mattias is an experienced gardener spending most of his free time on his knees among herbs, plants and garden vegetables. For the past two years he has been sharing gardening projects and how-to tutorials on the NordicLavender website and YouTube channel.