Thai Holy Basil needs light to germinate

That needs looking into, does it not?

Does Holy Basil Rama NEED light to germinate?

Shall we find out?

Needs light to germinate? Meaning the seeds do not need to be covered with soil to germinate them. It does kind of make sense with Basil seeds, I mean, have you seen the size of Holy Basil seeds? They are simply too small and lightweight to have any penetrative impact on the soil when they fall.

Basil is a plant that has adapted well to dry, sandy and arid locations, it is the reason their seeds produce a mucilage, once hydrated. Test have shown that the mucilage prevents moisture escaping from inside the seed. So, Basil seeds have a mechanism in place that allows their tiny little seeds to survive dry climates, once they have been moistened, clever stuff!

With this in mind, let's do an experiment...

To find out if Holy Basil germinates better when exposed to light, or is it simply the case Holy Basil is just capable of germinating if exposed to light, and perhaps a lightly buried seed, will in fact, germinate quicker (I already know covering them doesn't prevent them from germinating). We will see over the coming days / weeks.

So, here's a tray of Holy Basil Seeds (Rama). 14th Nov. 2023.

They are quite hard to make out aren't they. The plan is to cover one half of seed tray with a thin layer of soil over the seeds, the other half  the seeds will be left exposed to light.

Here's a closer view of the tiny little seeds. Their mucilage production is, in fact, quite a handy thing when planting them. When I scatter the seeds, it's very hard to see them against the background of soil, so, I spray them with water and wait ten minutes. When I return the seeds are quite a bright white and easier to see and thin out.

So here we go, a thin layer of soil added to the right half of the tray. The tray is now in the propagation chamber.

It is tempting to keep spraying the exposed seeds to keep them damp; not the best of ideas.

The mucilage is there to do that job, there is likely to be growth hormones and rooting compounds in the mucilage to kick start the seed, so the more you spray, the more the mucilage is diluted or even washed away, dehydrating the seed.

What next then?

We wait. 4 to 6 days usually. It will be hard to tell if the soil covered seeds are germinating at the same rate as the exposed seeds, because of the covering. I will choose an area to uncover regularly to check a small percentage of the covered seeds.

Ok Nature, do your thing, so I can update this post with some useful information.

UPDATE

17th November 2023 - We have results of the side by side test.

We have germination, on BOTH sides!

Here we have a seed just popped on the surface of the soil.

Here we have shoots from seeds buried under around 5mm of soil.

19th November 2023

Pretty close contest, but, the buried seeds have had to put more work in. My betting is they have a stronger tap root than the seeds that have not been buried.

24th November 2023

Pretty much exactly the same amount of seedlings a week on from 1st germination.

The buried seed side does have a slight lead, in as far as there are slightly bigger seedlings, with more leaf mass.

30th November 2023

Not a lot in it, is there. There are still seeds germinating on the side that the seeds where not buried.

The side that the seeds where buried, have grown quicker, even after having to work their way through the soil they were buried under.

Likely due to the fact that the buried seeds have had their tap roots forced deeper into the soil, accessing nutrient a little faster.

Quick side by side, same day ... terrible lighting, apologies. Buried seeds on the left, exposed seeds on the right. The center seedlings are thriving because the soil is more moist.

What does this mean?

Well, my conclusion is this; although holy basil seeds can germinate on top of soil, it is hard to keep them at the right moisture levels unless you can achieve close to 100% humidity. The buried seeds that have had constant 100% humidity in the soil, have managed to break through, the pressure of breaking the soil will of assisted in pushing a tap root down, further and quicker.

So, for healthier germination, and a stronger plant quicker, cover your Holy Basil seeds with 5mm of fine soil. Mist that layer, don't water it.

SIDE NOTE: I have a lot of pearlite in my mix. My future germinations will have a finer, non pearlite mix added on top of seeds.

I do hope this has been informative for someone.

As always, remain well.

Cheers n gone ...