, , ,

Last year, I started an auto irrigation project for my backyard.  This blog post documents this year’s one month focus (May 20th to June 20th) evolution of my backyard auto irrigation project.  Subsequent blog posts during this period will be build logs as the project evolves.  Hopefully by the end I will be gorging on fruits and vegetables. 🙂

Thanks To Those That Went Before

Hilary Dahl and Kellie Phelan for their excellent Encyclopedia Podcast.  They exuberantly share their knowledge about growing and are masters at creating a community spirit.  I learn a lot not only from the podcast but also from participating in the Slack Channel.

Backyard Growing Areas

Rather randomly and with only minor consideration of sun movement, I have three spots in my backyard that I plant vegetables that need to be watered.  I’ll start calling these:

  • strawberry swirl – here I am growing Seascape Strawberry Bndl of 25 [SPRING] strawberries from Rain Tree nurseries.  Why these? I learned from the Encyclopedia Botanica podcast Episode 37: Strawberries the difference between June-bearing and Everbearing.  I wanted Everbearing strawberries.  I chose Rain Tree nurseries because members of the Encyclopedia Botanica Slack Channel had bought strawberries from them and highly recommended.  I chose Seascape because the description made me drool and I think at the point I bought them other Everbearing varieties had been snatched up.

I snagged this image off of Google Earth.  It seems a bit old because the area identified as lower deck uses cold frames.




Strawberry Swirl Location 


Moisture Puck at Strawberry Swirl Location

  • Upper Deck – I have one area with snap peas, one area with cucumbers, and one area – I call the holding area because I put stuff there thinking I might transplant them somewhere else.  Currently there are tomatoes, rosemary, lavender.
  • Lower Deck – One cold frame contains potatoes spaced too close together, carrots, and a third cold frame that currently has succession lettuce I planted too late.  I think I’ll plant carrots here because I love carrots.  I love carrots so much my skin is orange.

The Goals

One goal that is core to everything is learning.  I am excited to evolve my knowledge of:

  • gardening.
  • hardware and software that I can put together to enhance my abilities.
  • building and putting together a complete solution to a challenge – in this case giving me time back as well as growing healthier plants.

From the Perspective of a Gardender

From my view as a gardener, my goals revolve around desperately trying to grow the most abundant and tastiest crops:

  • Save a significant amount of my time from having to drag out the hose and go around to the different spots within my backyard constantly watering.
  • Water the plants when needed, preventing overwatering and under watering.  Either of which can at the best lower the production and at the worst kill the plants.
  • Use only the amount of water needed.  
From the Perspective of a Hardware/Firmware/Mechanical Engineer:
  • Automatically water three different areas of my backyard when the soil is dry enough to cause plant stress.
  • Water only in the early AM or early PM.
  • Minimize the number of times the battery needs to be recharged (i.e.: maximize battery life).
  • Detect a malfunction.
  • Post analyze wet/dry soil behavior.
  • Stretch goal: inject the correct level/type of fertilizer into the irrigation.

The Equipment Setup

I used Google Draw to illustrate the setup:

Each planting area has a Moisture Puck (represented by the green dot).  The different colors – green, blue, and red – represent different communications going on:

  • green: communications between the Controller and a Moisture Puck.  The Controller has the same conversation with each Moisture Puck.  It’s a simple question from the Controller happening early AM or later PM asking the Moisture Puck to return it information on whether watering is needed.
  • blue: if the Controller decides the area being monitored by a Moisture Puck needs watering, it communicates with the spigot turning on/off the valve that is handling watering for that area.
  • red: the Controller sends me the moisture readings, inside temperature, and battery level of the moisture puck.  If the controller detects a problem – for example, the battery needs to be replaced, the temperature is too hot for the electronics within a Moisture Puck, or it hasn’t received readings for awhile… – it sends me an alert so I can follow up and fix the problem.

When To Water

The watering system starts watering when an analog value is read and interpreted by the code to mean the water is dry enough to water.  But what does “dry enough to water” mean?  I will be using the 1 to 5 plug tray moisture scale I learned about when I took a horticulture course from Dr. Fisher at the University of Florida.  Since watering only happens at most twice a day, I’m going to set “dry enough to water” to be within the 3 range of the tray moisture scale.  From my testing,


this will be when a moisture reading of 300 or less is read from the analog pin.

How Long To Water

As with when to water, how long to water is subjective.  My current plan is to water for 15 minutes.


…And off I go….