DIY Electric Soil Finger

I've just made a small device I can use to get readouts on when to water plants. This works by measuring the conductivity of plant soil. The conductivity changes according to how wet the soil is. This information is read and mapped as servo positions to indicate on a gauge when it's time to water.

Intro at instructables:
Today I'm going to show you how to make your own electric soil finger!

What's an electric soil finger you say? Allow me to explain: This is a sensor for measuring the amount of water in plant soil. This will then in turn show you whether or not it's time to water your plants, or if they are very much happy with the amount of water they have right now!

The inspiration for this was that I was constantly sticking my fingers in my plants dirt to learn if I needed to water them. However, this only gave an idea of the water on the very top layer of soil, no good!

I wanted a deeper and more quantifiable measurement and thus the Electric Soil Finger was born.

Let's get started!


UPDATE:
I entered this project in the Automation Contest over at instructables and I was lucky enough to win one of their runner up prizes! This prize includes an instructables t-shirt and a Teensy 3.2 microcontroller! Perfect for future projects with a lot of input/output handling.
I'll update with a picture of the prize when everything arrives.