Have you ever & ever thinking about growing plants that you can actually consume within your shortest distance possible? Well, I have made one for myself.
In Late November 2020, I have started my mini hydroponics installation on my rooftop! (Well, my parents rooftop actually). I have in total 2 different system with 3 installation and have harvesting one of them in 10 January 2021. The first plants came out is Lettuce!
As to why I choose lettuce, actually I didn't plan the type of plant to start but there are leftover in Lettuce seeds (which I have been used earlier in soil), so I decided to go with it without much thinking or preparing in prior.
To start with, the system I use for this plants is Wick System. The fact that this is the simplest installation, it is also the most affordable to create in my place! Basically in this type of system, we utilize the capillarity of the material used (such as fabric) to takes up the nutrition to the plant that resides in media bed (see the installation in "Wick Installation Setup").
Lettuce in my Wick System from Above
I was start planting from 27 November 2020 and it took me 2 weeks to transplanting the plant into the system. The thing I realize at the first pace is that in germination, this lettuce are grow faster compared to the soil as I have experience with it before, it even happen before I supplying the plant with nutrition which make me impressed by the first result!
After transplanting, I didn't aware of the specific needs of my plants and dozing the nutrition according to the recommended PPM only. I also didn't go with pH meter at first and finally realize the necessity after one week of transplanting, so you can say that I was rushing things at my first attempt.
As I push forward, many things come to mind such as the need for consistent light exposure, plant distance within installation, you named it! So in reality, it is really not a good consistent way of doing hydroponics and I strive to learn more in the future!
Lettuce in my Wick System Growing Environment
In this installation, I have tracked, monitored, and analyzing all of the measurement I can get over time. The variables I choose are separated within two aspect, it is controllable & uncontrollable. In controllable, I was monitoring Electrical Conductivity, pH, and Part Per Million. For the uncontrollable, I was monitoring environmental aspect such as water & ambient temperature, wind, humidity, dew point, pressure, precipitation, UV index, cloud covering, cloud height, and wind quality. I also realize that not all of those thing are significantly affected my plants growth, but the best thing comes into mind is to monitoring all of the available aspect possible in consistent manner.
The exciting part of my hydroponic is when I finish harvesting and able to analyze all of the data point in Python. So here's what I can tell about my lettuce growth cycle:
Upstart University Lettuce Reference Card
Before we start, I want to give some details for lettuce. The picture above was taken from Upstart University and has been my guidance in growing lettuce from 1 January 2021. I also believe that the information is relevant for lettuce. Unfortunately, it is to late for me to fixing things according to this card. So, keep in mind that this is the ideal condition for lettuce as we move forward.
Let's start here
The target with this analysis is to looking for:
Actual growing condition at my place
The best lettuce plant in my system
The worst lettuce plant in my system
The best situation to growing lettuce in my place
To begin with the analysis, I'd like to start from what kind of controllable variables in my crop cycle looks like.
Before Nutrition (Source Water)
Electrical Conductivity: 201-202.5 µS/cm2
pH: 6.95-7.2 (Neutral)
PPM: 100-101 PPM
After Nutrition (Solution)
Electrical Conductivity: 1297-1901 µS/cm2
pH: 6.2-7 (Neutral)
PPM: 649-954 PPM
*All of this numbers are produced from 25%-75% percentile of the data.
*The data collected via TDS meter and pH meter.
Later, the environmental factor (uncontrollable variables) I was in:
During the day
Wind Speed: 10-14 km/h
Water Temperature: 28.15-30.00 celsius
Humidity: 66-85 %
Wind Quality: 20.5-36.0 aqi
UV Index: 1-2
Cloud Coverage: 91.5-99 %
During the night
Wind Speed: 2-10 km/h
Water Temperature: 27.05-27.70 celsius
Humidity: 80.25-99.5 %
Wind Quality: 56.5-75.00 aqi
During the day and night
High Ambient Temperature: 29-32 celcius
Low Ambient Temperature: 22-25 celcius
Dew Point: 22.0-23.5 celsius
Pressure: 1006-1009 mb
Precipitation: 52.875-65.750 %
*All of this numbers are produced from 25%-75% percentile of the data.
*All of this number is captured from AccuWeather from my location.
After all of those controllable and uncontrollable value, you might grab the picture of my growing environment. Now let's focus on the controllable only because this is the aspect I can tweak.
Let's talk about Electrical Conductivity. When we talk about mineral fertilizer, usually we have potassium nitrate dissolved into water. Later, it split into two entities called ions. One become positive charge named cation (potassium ion K+), one become negative charge called anion (nitrate ion NO3-). Like potassium nitrate, other fertilizer dissolve in water and split into cations and anions
Electrical Conductivity (EC) is telling us how much your ionic concentration within your solution. The higher the concentration is, the higher the EC value are. So this can be used to indicating out solution strength
This graph is indicating the Electrical Conductivity (EC) contained from transplanting through harvesting. The orange line is the upper limit, the green line is lower limit, and the blue line is the actual EC
From this graph, we knew that most of the time, my EC is not adjusted properly and therefore, it contain a lot of waste in the nutrition. The reason I make this big mistake is because at first, I follow only the PPM value and haven't got the information about the EC. I also knew that there are variations in TDS meter that measure nutrition in PPM, I mean the value produced may vary because the different ratio applied to the conversion from EC to PPM based on your location, therefore I am not recommending using it for the measurement because we don't really know what ratio used in our TDS meter nor at which the PPM value we found on internet is shooting for.
I start to adjusting towards the appropriate EC from 2nd January 2021 but it was to late, even thou it's better than nothing! Maybe, tips from me is to adjusting the EC in the lower to middle range as my system tend to increase the EC value over time.
Next, let's talk about pH. pH itself is showing how acidic or basic the solution is and strongly impacting what type and how much nutrients element we can deliver towards our plants.
This graph is indicating the pH we have from transplanting through harvesting. The orange line is the upper limit, the green is the lower limit, and the blue is the actual pH.
To be honest, I start measuring pH after 1 week transplanting. I learn that pH could be one of the most important aspect we have to measured as it can cause nutrient deficiency for our plant.
But even after realizing that, I haven't adjusting it since I need things called pH up and pH down and have been suggested at first to stay away from it. After taking some time to understanding the situation, I learn that for inexperienced people like me, I might just adjusting it over time based on the value I shoot for and ignoring the bad possibilities especially if I dosing pH down repeatedly (which is constantly make my solution more acidic). This attempt, may cause a problem so to avoiding it, I have to change the water at least once per week before it hurting my plant.
For lettuce in particular, I constantly facing one big issue as from 1st January 2021, my pH is rapidly suffer from sudden pH spike. Usually the solution I used is having maroon color, but suddenly my solution is changing color to yellow as the pH rapidly up! I might assuming that this phenomenon caused by the drastically different amount of nutrition I apply at the beginning and the last. My plant may get shocked and therefore damaging it by up taking the acidity from the solution which caused rapid approach towards basic solution.
This graph in particular showing how much plant growth (in cm) I can get from transplanting through harvesting. It start with plant no 13 because the plant number 1-12 are filled with Pak Choi.
In this graph, I learn that there are lots of growth variation and actually some of them (no 14, 15, 18, 21, and 24) are having bad postures (tall postures). This problem is occur as in this plant positions, the plants is covered by Pak Choi leaf, therefore creating shade in the lettuce. My suggestion are to avoid any type of shading and distribute the light evenly.
Next, this graph in particular showing how much leaf harvested and the amount of leaf loss in each plants. Again, I have lots of variation in it. Some of the plants even having more leaf loss than the leaf harvested! Later, I will tell my assumption on this phenomenon below.
After all analysis about the plant growth and plant leaf, I find out that lettuce number 16 is the best and number 22 is the worst. To make this judgement, I look first on which plant has produce most leaf except for the plant that have tall postures. Second, I choose the plants which has the least leaf loss. Both of this criteria means that the plant I choose is the plant that able to producing maximum amount of leafs and have a great resistance towards sustaining the leafs, also not having tall posture. The worst plant itself chosen by the same criteria, but I take the worst version on it.
This graph showing the particular growth of both the best and worst plant. The blue line showing the best plant growth (no 16) from time to time and as you can see, at first pace, it is being overlapped by worst plant growth (no 22) and starting to catch up after 3 days transplanting. Later we also see some abnormality in plant growth after 6 January 2021, I assume this is because the pH swing.
This graph showing the amount of leaf produced (blue line) and the leaf loss (orange line) in the best plant. We can see that this lettuce hasn't lost its leaf before pH swing.
Same as above, this graph showing the leaf produced and leaf loss but for the worst plant. This plant has suffered badly from the pH swing and caused the leafs to yellowing. After normalizing the pH, it cannot regain all of the damage caused by nutrient deficiency, but I am grateful as it still work for some leaf thou.
This graph in particular showing us the time when my plant growth exceed 2 cm /2 days. Growth count means that how many plants has growth to more than 2 cm / 2 days. This graph finally become my criteria for choosing the best condition to grow lettuce within my environment.
From the bar, we can see that both 25 December 2020 and 3 January 2021 have most of the plant growth that exceed 2 cm/ 2 days. Later, to determine the best condition, I'm calculating the total height produced. I got 23.9 cm for 25 Dec and 24.9 cm for 3 Jan, so I choose 3rd January 2021 to become the starting point. The caveat is, I realize that at this time, the solution is suffering from the pH swing and therefore, even thou it is indicating that 3rd January is the best condition, I prefer to look back and choose 2nd January. Second reason, I measured the at 10:00 AM in 3rd January, so it means that my measurement is not the 3rd January final growth.
Here is the best condition:
After Nutrition (Solution)
Electrical Conductivity: 1187 µS/cm2
pH: 6.7 (Neutral)
PPM: 593 PPM
Later, the environmental factor (uncontrollable variables) I was in are:
During the day
Wind Speed: 11 km/h
Water Temperature: 29 celsius
Humidity: 75%
Wind Quality: 24 aqi
UV Index: 1
Cloud Coverage: 98 %
During the entire day
High Ambient Temperature: 30 celcius
Low Ambient Temperature: 24 celcius
Dew Point: 22 celsius
Pressure: 1007 mb
Precipitation: 61 %
Lettuce Before Harvesting
Lettuce After Harvesting
After I done with the analysis, I have realized that there is lots of mistake I made in the process, and here's the tips:
Instead of only allocating 2 weeks from seedling to transplanting, I might try with 4 weeks.
To prevent from yellowing, I will dose the water with pH up & pH down to shoot for the pH range and change the water once per week.
With wick system, I tent to dosing upper range amount of EC because I still have buffer and constantly reducing the EC as the roots reach the solution directly.
To prevent from nutrient overdosing, I will only cling into EC value and adjusting it towards appropriate EC range instead of using PPM.
I have created hydroponic installation that is to tight in terms of distance between plants. This condition are creating shade for the typical wide plants and make the leaf easily ripped (cause by the fraction between plants leaf), so next time I have to take consideration to only put tall posture plants in it (let's say coriander) or build another installation that has wider distance to avoiding plant shade and ripped leaf for lettuce!
I might wanted to measure the leaf width, so I could get a better picture of my plant growth.
Last thing, if you were curious about the data I used, you can download here
and download the python code here
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