Hydroponics: Experimenting with how the duration of light exposure affects the growth of lettuce.

Using an entire wall indoors, we will try our hand at hydroponics using PVC pipes.

I used light bulbs to germinate leaf lettuce by continuously shining light on them in three patterns: 0h, 12h, and 24h, to see what kind of difference the light exposure time makes.
It seems to be a photophilic plant, so I guess I can understand the results to some extent without actually doing it, but I’ll give it a try.
The lettuce in the middle of the photo above has grown so well that it is now tall enough to hit the light in the shading device, so I moved it to the hydroponics unit.
If you want to watch the video, please click the link below.

Here you go.

Moisten the container with a sponge and sow lettuce seeds.

Prepare a suitable container (in this case, a cut plastic cup) and cut a sponge to fit the container.
Moisten the sponge with water and sow the lettuce seeds on it.
There is also a method of covering the sponge with toilet paper to prevent it from drying out, but it was too much trouble, so this time I sprayed water on it with a mist sprayer.

Shading with PVC pipes and controlling the lighting on/off with a smart plug

Shade the seeds.
The 0h seeds will not be exposed to any light, so we will cover them with aluminum foil and leave them there.
The 24-hour seeds will be exposed to light all the time, so I hung a light bulb

inside a PVC pipe and covered it with aluminum foil.

The 12h seed will be lighted for 12 hours, shaded for 12 hours, and then repeated.
You can turn the bulbs on and off manually, but since I had an extra smart plug, I automated the lighting on and off.
It was a smart plug from a company called Meross, so I installed a special app and the lights turn on at 16:00 and off at 4:00 in the morning, repeated daily.

Lettuce growth rate one week after sowing

It has been two days since seeding, and none of the 0h lettuce, 12h lettuce, or 24h lettuce has germinated.

I forgot to observe it on the third day, and now it’s the fourth day.
It’s a bit scrawny. Super scrawny.
This one might not make it.

This is a 12-hour light-irradiated lettuce, and it germinated without any signs of overgrowth.
I just put the seeds on it, but the germination rate is good and it looks a little small.

Here are the lettuce seeds that were left under the light for 24 hours.
They germinated, but they seem to be a little smaller than the 12-hour lettuce.
Considering the time it takes to germinate, 12 hours of light and 12 hours of shading seems to be a good idea.

It’s been six days. The lettuce, which is shaded all the time, is no longer good.

The lettuce has been shaded for 12 hours with a 12-hour light, but many leaves have come out.

This is the lettuce that has been exposed to the light for 24 hours.
Compared to the lettuce that was exposed to the light for 12 hours, each leaf is larger and the leaves seem to be more spread out.
I wonder if this is because they absorb more light.

One week has passed.
As for the 0h lettuce, there is nothing more I can do to save it, so I will end my observation.
As for the 12h lettuce, the leaves themselves are getting bigger, but the opening seems to be weak.
It looks like it is growing upwards.

This is the 24h lettuce a week later, and the leaves have opened up nicely, and the main leaf (or is it called that?) is growing out from the middle. It looks like it is growing the best.
It looks like it is growing the best.

How much lettuce has grown in the last 10 to 18 days

This is the 12h lettuce, which is now on its 10th day.

This is the 24h lettuce.
The leaves seem to be more vigorous than those of the 12h lettuce, and the main leaves (I wonder if they’re called that?) are bigger. I wonder if 24 hours of continuous light is the right way to go.
I wonder if it’s right to expose them to light for 24 hours straight…

This is the 24h lettuce.
The leaves seem to be more vigorous than those of the 12h lettuce, and the main leaves (I wonder if they’re called that?) are bigger. I wonder if 24 hours of continuous light is the right way to go.
I wonder if it’s right to expose them to light for 24 hours straight…

This is a 24-hour light-irradiated lettuce, and the color of the leaves is starting to look like sunny lettuce.

This is the 12h lettuce on day 18.
I thought, “Maybe this is the one that needs to be thinned out in the middle? But it was already too late.
The result might have been different if I had thinned it out when it was in the twin-leaf stage. Let’s go back in time.

This is a 24h lettuce.
The main leaves are growing in earnest and getting bigger, and I noticed that they were almost touching the hanging lights.
If I don’t think about thinning (which I should), it seems that the sunny lettuce will grow faster if it is exposed to light 24 hours a day.
I’d like to end the experiment on the 18th day, as it looks like it’s not good for the lettuce to be exposed to the light directly.

Replanting the grown lettuce plants into the hydroponic system

 

The grown lettuce plants were transferred to the hydroponics unit.
I took the lettuce and sponge out of the cup and gently loosened the roots growing from under the sponge so as not to cut them.
Inside the processed PVC pipe (gray pipe), water with liquid fertilizer and oxygen is circulating.
After loosening the roots until they are long enough to soak in the water, I set the lettuce in the PVC pipe.
We have installed LED lights near the lettuce plants, so they will continue to be exposed to light 24 hours a day, but will they ever be harvested?
In other words, if it harvests well, there will be a follow-up report, if it dies, there will be no follow-up report.