Keeping plants healthy sounds simple until real life gets in the way. Busy schedules, changing seasons, indoor heating, and inconsistent lighting conditions all affect how plants grow. Most plant problems do not happen overnight. They build slowly through small environmental changes that are hard to notice without measurement. By the time leaves droop or turn yellow, the damage is often already done.

Plant Watcher is designed to solve that problem. It is a compact, battery powered monitoring system that continuously measures the conditions your plant experiences and reports them automatically. Instead of guessing when to water, move a plant closer to the window, or adjust humidity, you get clear data and timely warnings.

Built using Soldered hardware and reliable environmental sensors, Plant Watcher turns any plant into a connected system that quietly works in the background while you focus on enjoying your space.

What Is Plant Watcher

Plant Watcher is a low power IoT plant monitoring project based on the Soldered DeepSleep NULA board using the ESP32-S3 microcontroller. The system periodically wakes from deep sleep, reads multiple sensors, connects to WiFi, sends the data to a webhook endpoint, and then immediately returns to sleep.

This approach allows Plant Watcher to run for long periods on battery power while still providing regular updates. There is no screen that needs to stay on and no continuous wireless connection draining energy. The device exists only to collect accurate measurements and deliver them where they are useful.

The project is suitable for indoor plants, office greenery, greenhouses, seed trays, and any environment where long term monitoring provides insight that occasional manual checks cannot.

Why Environmental Monitoring Matters for Plants

Plants respond to their environment continuously. Light, temperature, humidity, and soil moisture all interact to determine growth rate, leaf structure, and overall health. Problems arise when one of these parameters drifts outside the ideal range for too long.

Overwatering is one of the most common reasons plants fail indoors. Without feedback, soil that appears dry on the surface can remain wet deeper down. Conversely, soil can dry out faster than expected in warm or well ventilated rooms. Measuring soil moisture removes uncertainty from watering decisions.

Light is another frequent issue. Many plants survive in low light but do not thrive. Gradual light deprivation often results in weak stems, pale leaves, and slow growth. Measuring ambient light levels makes it clear whether a plant is receiving enough usable light throughout the day.

Temperature and humidity influence transpiration and nutrient uptake. Dry air caused by heating systems can stress plants even when watering is correct. Temperature near roots can differ significantly from room temperature, especially in large pots or near windows.

Plant Watcher addresses all of these factors using dedicated sensors designed for accuracy and stability.

Hardware Overview

Plant Watcher uses a carefully selected set of components that balance measurement quality, power efficiency, and simplicity.

• Soldered DeepSleep NULA board with ESP32-S3
• LTR-507 light sensor breakout
• Capacitive soil moisture sensor
• SHTC3 temperature and humidity sensor
• DS18B20 waterproof temperature sensor

The DeepSleep NULA board is the foundation of the system. It is optimized for low power operation and makes full use of the ESP32-S3 deep sleep capabilities. This allows Plant Watcher to wake only when needed and remain powered down the rest of the time.

The LTR-507 sensor measures ambient light levels, giving insight into how much usable light reaches the plant. This data is essential for understanding growth limitations related to placement.

The capacitive soil moisture sensor measures soil water content without corrosion. Unlike resistive probes, capacitive sensors do not degrade over time and provide more consistent readings.

The SHTC3 sensor provides accurate air temperature and humidity measurements. It is well suited for battery powered applications and reacts quickly to environmental changes.

The DS18B20 waterproof temperature sensor allows direct measurement of soil or water temperature. This is especially useful for larger pots, hydroponic systems, or plants sensitive to root temperature.

Battery Powered by Design

Plant Watcher is designed to operate on battery power for extended periods. This is achieved by minimizing active time and eliminating unnecessary power usage.

During operation, the device follows a strict cycle. It wakes from deep sleep, initializes the sensors, takes measurements, connects to WiFi, sends the data, and immediately shuts down wireless functions. After that, it returns to deep sleep until the next scheduled wakeup.

Because WiFi is only enabled briefly, power consumption remains low. The wake interval can be adjusted depending on how frequently data is needed. Short intervals provide more granular tracking, while longer intervals extend battery life.

This design makes Plant Watcher practical for locations where running cables is inconvenient or undesirable.

How Data Is Collected and Sent

Each wake cycle begins by initializing all sensors. Light intensity is read from the LTR-507. Temperature and humidity are sampled using the SHTC3. Soil temperature is obtained from the DS18B20. Soil moisture is measured via the capacitive sensor and converted into a percentage.

Once all values are collected, the ESP32-S3 connects to a configured WiFi network. A JSON payload containing all sensor readings is then sent via HTTP POST to a webhook endpoint.

This webhook approach keeps the system flexible. The same firmware can be used with many different platforms without modification. The endpoint can forward data to dashboards, databases, automation systems, or notification services.

In addition to regular measurements, the firmware can send conditional alerts. For example, if soil moisture drops below a defined threshold, an additional warning message is transmitted. This allows rapid response without constantly checking logs.

Example Arduino Implementation

The following Arduino sketch demonstrates the complete Plant Watcher workflow. It initializes all sensors, sends data to a webhook, and enters deep sleep to conserve power.

#include <SHTC3-SOLDERED.h>
#include <OneWire.h>
#include <DallasTemperature.h>
#include <LTR-507-Light-And-Proximity-Sensor-SOLDERED.h>
#include <WiFi.h>
#include <HTTPClient.h>

LTR507 ltr;
SHTC3 sht;
OneWire ow(7);
DallasTemperature ds(&ow);

const int SOIL_PIN = 6;
const char* SSID = "your ssid";
const char* PASS = "your password";
const char* WEBHOOK = "your webhook id";
const int SLEEP_S = 300;

void setup() {
  Serial.begin(115200);

  ltr.init();
  ltr.setALSGain(LTR507_ALS_GAIN_RANGE1);
  ltr.setALSMeasRate(LTR507_ALS_MEASUREMENT_RATE_100MS);

  if (!sht.begin()) while (1) {}
  ds.begin();

  uint16_t light = ltr.getLightIntensity();
  sht.sample();
  float hum = sht.readHumidity();
  ds.requestTemperatures();
  float t18 = ds.getTempCByIndex(0);

  int soilADC = analogRead(SOIL_PIN);
  int soilPct = constrain(map(soilADC, 3200, 1200, 0, 100), 0, 100);

  WiFi.mode(WIFI_MODE_STA);
  WiFi.begin(SSID, PASS);
  while (WiFi.status() != WL_CONNECTED) delay(250);

  HTTPClient http;
  http.begin(WEBHOOK);
  http.addHeader("Content-Type", "application/json");

  String payload = "{";
  payload += "\"light\":" + String(light) + ",";
  payload += "\"hum\":" + String(hum,2) + ",";
  payload += "\"temp\":" + String(t18,2) + ",";
  payload += "\"soilPct\":" + String(soilPct);
  payload += "}";

  http.POST(payload);

  if (soilPct < 80) {
    http.POST(String("{\"warning\":\"soil_low\",\"soilPct\":") + soilPct + "}");
  }

  http.end();

  WiFi.disconnect(true);
  WiFi.mode(WIFI_OFF);

  esp_sleep_enable_timer_wakeup((uint64_t)SLEEP_S * 1000000ULL);
  esp_deep_sleep_start();
}

void loop() {}

Where Plant Watcher Fits Best

Plant Watcher is ideal for users who want long term insight rather than constant interaction. It works well as a background system that quietly collects data and only demands attention when something needs to change.

It fits naturally into smart homes, workspaces, classrooms, and growing environments where understanding conditions over time leads to better decisions. Because the system is open and extensible, it integrates easily into existing workflows.

Conclusion

Plant Watcher transforms plant care from intuition into informed action. By combining low power hardware with accurate sensors and simple data delivery, it provides visibility into conditions that usually go unnoticed.

Instead of reacting to visible stress, you can prevent it. Instead of guessing, you can measure. With Plant Watcher, your plants gain a quiet observer that works continuously so you do not have to.

For anyone serious about plant health, sustainability, or smart monitoring, Plant Watcher offers a practical and reliable foundation.