I grow a lot of coriander. Or cilantro, as you may prefer to call it. But germinating coriander seeds can take time. And it can be challenging.
It is normal to wait 2-3 weeks or longer for the seeds to germinate and sprout seed leaves.
And before the seeds germinate, you 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 over-seeder. I use too many seeds per starter pot, but I prefer to increase my chances and will deal with the risk of overcrowding later.
I prefer over-seeding to pre-germinating coriander seeds as the new roots are very delicate and difficult to handle.
Transplanting coriander and dealing with overcrowding
Overcrowding means a more complicated process when it is 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, if needed, by harvesting young leaves for salads, dressings, and cooking.
I would stop over-sowing 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.
- Coriander seeds straight from the seed packet
- Soaking coriander seeds for 48 hours before planting
- 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 centimeters/ 3 inches).
Progress is checked and reported every week. I will pick the winner when the first set of seedlings is large enough to be transplanted into 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 three 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 it seems that crushing the seeds is the most effective way to germinate them faster.
Today, exactly one week after planting the crushed coriander seeds, I saw two sets of first leaves.
And the larger of the two germinated already after four 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 affect how quickly the seedling will grow.
And will the seedling grow 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.
Soaking and planting the seeds straight from the seed packet is lagging.
I see the 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 well. There are true leaves from 3 out of 8 seeds and the first leaves from 2 more.
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 will be ready to call a winner next week.
Time will tell. Stay tuned.
Week 3: (Day 15-21): Will crushed coriander seeds still be ahead
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 already saw true leaves from the crushed seeds last week (week 2). I am still not seeing true leaves from the soaked or natural coriander seeds.
And yes, I have grown several test pots to confirm the findings, which still hold.
On a side note, I can almost get soaked seeds to germinate as fast as crushed seeds. But not every time.
But 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.
