DIY Plant Moisture Sensor W/ Arduino

See this project on my website!

This project will calculate the water content of soil around a plant by measuring the dielectric constant (the soil's ability to transmit electricity) and will alert you with a red LED when the plant needs more water or a blue one when it has too much.

Step 1: Materials

You will need to gather these things in order to build this project.

• Arduino UNO or equivalent (x1): https://amzn.to/2DLjxR2
• 220Ω* resistors (for LED) (x3): https://amzn.to/2S2sV5R
• 10kΩ resistor (x1) - brown black orange: https://amzn.to/2S2sV5R
• RGB LED (x1) or 3 different colored LEDs: https://amzn.to/2Fzbusx
• Long Jumper Cables (x2): https://amzn.to/2Q7kiKc
• Jumper Cables (x6): https://amzn.to/2Q7kiKc
• Breadboard (x1): https://amzn.to/2RYqiSK
• Bolts of any size (x2): https://amzn.to/2qWLYTF
• Nuts same diameter as bolts above (x2): https://amzn.to/2qWLYTF

Step 2: Create Sensor Prongs

You will need to repeat this step twice (once for each prong).

1. Begin to tighten the nut around the bolt
2. Slide the end of the long jumper cable between the nut and the head of the bolt.
3. Finish tightening the nut until you are unable to pull out the jumper cable

Step 3: Create the Circuit

Follow the schematic or the breadboard image - whichever one works better for you. The wires labeled "out" are the two prongs you just created.

Step 4: Upload This Code

Pretty self explanatory here. Just upload this code to your Arduino!

Step 5: Place Sensor Prongs

1. Insert the prongs you made about 1" to 1.5" apart in soil close to the plant you want to monitor.
2. Give the plant a healthy amount of water and open the serial monitor
3. It should give you readings around 25 - 30% if you gave it the right amount of water
4. If not, try moving the prongs around to get it right (or you just added too much water)

Step 6: Outdoor Protection

If this is going outside you will want to put your circuit inside of a Tupperware or other waterproof container to protect it from the elements. Then drill some holes for the sensor wires to come through and add a battery box to power it (see here for how to do that). Mine is not going outside though, and will be fine without a container.

Comments

[LarryF24]

I know you wrote this a few years ago but I am curious about the math here. When I create this project I get the green led to light and it is in air, I realize air has a humidity but just curious how I would check the math related to the percentages . In free air I get 1% reading on the monitor green led (pin2) lit.I would think that the blue led would be driven high but maybe I am not understand it correctly. Your math percent = 2.718282 * 2.718282 * (.008985 * moistVal + 0.207762);caculates the percentage of moisture, could you please step me through it, math is not a very strong subject for me. I assume that the first and second values are multiplied together and the second value would be the probe readings + a value divided into the first value to give you the result. Is this correct? I am trying to grow a peach tree in my office from a seed, I have a plant so far and wanted to monitor the value of the soil,worked hard at getting this to even grow, all others died. I read that the soil moisture should be between 21% to 40%,this circuit could help me with my plant ,thanks.

[starbase-01]

Hello. Do you know of any projects that team this sensor up with a wifi project so that the sensor data can be accessed remotely?

[kelly25]

Hi, can you please name those steps, please. I'm sorry to require you like this, but I can't name it step by step and it's only showing the chart for us. thanks

[FabrícioB3]

Hi. I would like to know where did you get the formula from. I noticed it starts with e^2, but what are the other values, and where did that come from? Thanks

[judithh33]

me podria ayudar yo quiero detectar la humedad de un pañal y que mande un aviso al celular del que el pañal esta mojada como podria hacer eso ?