Smart plant sensors with Home Assistant

Intro

I am quite fond of having different plants spread throughout the house. It takes a bit of forethought, as I always need to check if they are cat safe first. Despite how much effort I put into keeping them alive, sometimes they just die. This became incredibly frustrating, and I decided to take a smarter approach and use smart plant sensors to try and keep them alive and well.

Heads up

Even though I have been using the plant sensors for over two years, some plants will still randomly just die. This is by no means a foolproof way to keep plants alive!

I already run Home Assistant so it was only natural that I added the plant sensors into it.

Materials

• Plants
• Xiaomi MiFlora plant sensors (Bluetooth)¹ (between 15 and 20€)
• ESPHome Bluetooth proxies² (4 to 10€ each, but they are not required specifically for this, you can leverage existing ones)

Home Assistant components

• homeassistant-plant - the central component that creates the plant entities in Home Assistant.
• home-assistant-openplantbook - used to retrieve generic plant details, ie, how much to water them or how much light they need.
• lovelace-flower-card - used to display the plant information in a nice, easy to read card.

All of these are custom components, but they are really easy to install via HACS, the Home Assistant Community Store.

When creating the plant entity, you pick the species and the openplantbook component automatically retrieves the the recommended ranges for each.
Each plant entity gives you a binary state (ok/problem), and the attributes tell you how each of the different measured items are within the acceptable range. They are:

• soil moisture,
• temperature,
• soil conductivity (corresponding to quantity of minerals on the soil),
• illuminance (the current amount of light being received),
• dli, daily light integral (the accumulated amount of light received today),
• air humidity, which isn’t measured by the Xiaomi MiFlora sensors, but you can take them from a Temperature/Humidity sensor, if you have one.

The plant entity details within Home Assistant.

Each plant's information gets displayed in a neat card. I am using the compact version, but the symbols correspond to (top to bottom, left then right): air humidity, soil conductivity (ie, quantity of minerals on the soil), accumulated light received today, soil humidity, temperature, and light received.

Automating notifications

To make my life easier, rather than checking the cards each time, I have set up automations to let me know a plant needs watering, or plant food.

You can set up an automation with a trigger based on the problem status:

trigger: state
entity_id:
  - plant.butterfly_palm
  - plant.peperomia_santorini
  - plant.mistletoe_cactus
  - plant.*every other plant
from: ok
to: problem

and then a notification to your desired devices. I have my notifications set up in Node-RED, so the below isn’t your standard Home Assistant format.

I have them set up in a way that only generates a notification if any of the attributes below is low. The below message is used as the template:

The {{payload.attributes.friendly_name}} needs some attention!
Moisture: {{payload.attributes.moisture_status}}
Soil Conductivity: {{payload.attributes.conductivity_status}}
Temperature: {{payload.attributes.temperature_status}}

I then send out the notification via Home Assistant:

{
   "message": payload,
   "data": {
       "channel": "Plants",
       "timeout": "1800",
       "clickAction": "/lovelace/plants"
    }
}

The timeout automatically dismisses the message after 30 minutes, to avoid cluttering my phone. The “clickAction” means that if I click the notification on the phone I am taken to my plants dashboard, so that I can view the cards and check which plants need to be taken care of.

Conclusion

This is a very simple way to try and keep the plants alive. Considering the price of the sensors, one could argue that you might be better of buying a new plant each time one dies. I still feel better knowing I am doing all I can - and a reminder on the phone when it is time to water a plant really helps.
I have found that, overall, having the sensors does help in keeping plants alive longer. Yes, some of them still die randomly (maybe I am not good enough at this!), but even those seem to last longer than what they did when I had no sensors at all. And some of my other plants are really thriving! One in particular, the Fishbone Cactus (Epiphyllum anguliger) has been doing so well that I have managed to propagate small cuts from it into 2 new pots.

Footnotes

1. I’ve looked into different options, and found these to be by far the cheapest, especially if bought in bulk. They do go through something like a CR2032 battery per year. ↩

2. I have plants spread out throughout the house, with some even outside. ESPHome Bluetooth Proxy functionality allows any of my ESP32 devices to pick up the Bluetooth signal and relay it to Home Assistant. They are not needed specifically for this, they just help in ensuring you can cover a wider area. ↩