Are the design files available?  Is there a git repo for this project?

thanks!

Ask and you shall receive: https://github.com/Cannonball2134/EasyPlanter

Note: There was a problem with version 1 of the boards. The Tx and Rx pins need to be swapped around.

Awesome, thanks!

Note: There was a problem with version 1 of the boards. The Tx and Rx pins need to be swapped around.

This looks a lot more expensive than a simple wiring mod to a £1 solar garden light from Poundland. Either will tell you if your soil is too dry, and the solar light needs no batteries.

However, of course your technology is more fun ;-)

Attach a BLE or Wifi chip to a poundland solar light, along with a simple moisture sensor..... sounds like a good hack :) Let me know when you release the instructable ;)

I dont think the solar cell and battery would have enough capacity for BLE or Wifi - maybe a low power radio. However just for the light to come on when the soil is dry, see this instructable at Sparkfun. The voltage sensing in the chip which turns on the LED at night is repurposed to measure soil resistance - works a treat. I have done it using some corrosion resistant wire around the spike at  the base of the LED garden light.  I found that the aluminium tube of the lamp as one electrode  tends to develop more resistance on exposure to water, so probably two corrosion resistant wires are best (stainless or other alloys).

https://learn.sparkfun.com/tutorials/soil-moisture-sensing-by-hacking-a-solar-light

Did you get some experiences with titanium wires like stated "Another possible solution i am looking into is using titanium wire for the sensing probes, as pure titanium is resistant to corrosion." ? Btw cool project, I wanna build a wireless moisture sensor with the esp8266 this summer. So I'am looking for right wires as well.

I did go ahead and order some titanium wire but sadly other projects and work popped up, so i have not had a chance to experiment with it. If you do use it l would love to know how well it works.

I've heard if you alternate DC polarity between resistive checks, you can minimize corrosion.

I've also heard that capacitive sensing uses less energy and doesn't corrode since the sensor is only capacitively coupled to the soil.  This guy sells them: https://www.tindie.com/products/miceuz/i2c-soil-moisture-sensor/

Once ESP86 comes out, it's supposed to include BLE; that may be the way to make it lower cost..

Thanks Pete, that's a great suggestion. Capacitive sensing looks very interesting, i might have to incorporate that into a future design. 

Great project, what method do you use to measure the soil mosture? I guess resistive?

Thank you, and you guessed right, it is resistive. However,  i haven't extensively tested the sensor's lifespan when exposed to a moist environment, and given the coating is copper, it might corrode quite quickly. Therefore I am still looking for better options. 

Great project--I could use a few of these too. 

Thanks. I am trying to make it cheaper so that everyone can have one.