Here is my automation for watering my balcony in a zone10 climate with a ton of sun.
I hope this helps someone - it’s been working flawlessly for months.
What started me thinking I could do this economically is the wireless soil sensor is only $12 and the valve I control is only $20!
Home Assistant Watering Automation
Features
- Inexpensive! Even if you have to buy everything, it’s less than one of those “smart” valves.
- Fail safe - water can only flow while there is power and running software
- Water as needed - only waters soil if humidity falls below configured level
- Water Only water within specific time window (user defined)
- Water at a controlled rate / frequency (user defined)
- Optional Logging and mobile alerts when run
Challenges that inspired me to automate
- Zone 10 garden on balcony - Full sun for weeks and then cloudy for a week.
- Could only water before sunrise
- Starting plants required above average attention and care
- Our particular plants do best when soil is allowed to dry
- Frequently away from home traveling
- Must water very slowly to minimize impact on neighbors and sidewalk below us
- Wanted to conserve as much water as possible
How it works
- The soil sensor reports soil humidity level (and air temp and battery power) approximately once every 10 minutes 24 hours a day, 365 days a year. This is done wirelessly @433.92mhz up to 100 meters.
- The RFXtrx controller decodes the message and sends it via USB to the rfxtrx software component running in Home Assistant
- The rfxtrx component reports humidity (and temperature…) state updates on sensors defined in configuration
- The new humidity state triggers the automation in Home Assistant
- The watering automation inspects the state of the soil, the time of day, the last time it watered, and decides if it’s ok to “push” the water button switch which starts water flowing.
- The zwave switch passes current to actuated pneumatic valve to “open” (spring otherwise holds close) allowing water to flow through to a long soaker hose.
- After 10 minutes, water flow to soaker hose is shut off.
Depending on soil absorption, hose type, water pressure, and so on - it might water for 10 minute increments for 2-3 hours. It’s all how you configure it. For my balcony, most of the time it waters for ~ 20 minutes over 2 hours. You could easily have it run once for an hour, or for 5 minutes, every hour… and so on.
If you don’t have a switch that automatically turns off (failsafe), you could easily have it turn the switch off after an arbitrary number of minutes by adding two more lines to the automation.