Automate Greenhouse Watering with HomeKit

Recently, I’ve been able to replace a pile of equipment to automate greenhouse watering with three small HomeKit devices from El Gato. Here’s the pile:

Obsolete Automation

Here’s the story. I’m responsible for ensuring that a 72 square foot greenhouse does not cook or dry out the plants within. There are two sets of misters in the greenhouse – the lower misters and the upper misters. The misters themselves are patio misters.

The lower misters are below the benches and can be left on for long periods to increase the humidity in the greenhouse. The upper misters are above the benches and must be limited to short stretches, as they get water on the plants, which tend to die if overwatered.

In an ideal world, the misters work like this:

  1. Active only from 10am to 5pm, maybe a bit later in the early summer
  2. Lowers on when the humidity drops below a certain point, and off back above that point
  3. Uppers on only when the temperature exceeds a certain value, and off once cooler

Until recently, I would approximate this using timed valve controllers at the faucet, followed by electrically activated solenoid valves attached to either a humidistat (for the lower misters) or a thermostat (for the upper misters). To limit time of day, I plugged all the electrical components into a mechanical timer. The picture above shows everything except the solenoid valves, which I still use.

Enter HomeKit

Enter the El Gato Eve Weather, two El Gato Eve Energy, Apple’s Home app, and the Eve app.

I plugged each solenoid valve into an Eve Energy, so now I can control upper and lower misters independently. I put an Eve Weather into the greenhouse, so I’ve got real-time temperature and humidity. I set a Timer in the Eve app to limit when the misters are active (#1), and I set Rules for the lower and upper misters (#2 and #3).

The icing on the cake was when I learned that I could set up my AppleTV as my HomeKit hub to monitor and manually control all of this when I’m away from home.

HomeKit and El Gato have greatly improved my greenhouse automation, eliminated a pile of fussy equipment, and offered me remote access. Needless to say, I’m thrilled.