How to Measure Soil Moisture and Use It in Automatic Plant Watering Systems

Keeping plants healthy isn’t just about giving them water — it’s about giving them the right amount at the right time. Too little water can cause wilting, while too much can suffocate the roots. That’s where soil moisture measurement and automatic watering systems come to the rescue.

In this post, we’ll explore how to measure soil moisture accurately, what tools you can use, and how to automate your watering process using SPIKE prime

Why Soil Moisture Matters

Soil moisture refers to the amount of water contained within the soil pores. It’s a critical factor that affects:

• Plant growth: Determines how much water is available for uptake by roots.

• Nutrient absorption: Many nutrients dissolve in water, making them accessible to plants.

• Soil health: Prevents soil from drying out or becoming waterlogged, both of which harm beneficial microbes.

Monitoring soil moisture helps you maintain a healthy balance — ensuring plants get just what they need.

Methods to Measure Soil Moisture

        Capacitive Soil Moisture sensor  for Spike Prime are widely used in classroom and DIY gardening systems.

• They measure the dielectric permittivity of the soil — which changes with water content.

• The output is an percentage of  moisture level.

• it is Long-lasting harsh environment of plant soil. (unlike resistive sensors that corrode over time).

Components You’ll Need

• Capacitive Soil Moisture sensor for SPIKE Prime

• Water pump 

• SPIKE Prime

Basic Working Principle

1. The sensor measures the current soil moisture.

2. The SPIKE Prime compares this reading to a threshold value you set (e.g., 25%).

3. If the soil is too dry, it activates the pump to water the plant.

4. Once the moisture level rises above the threshold, the system turns off the pump.

This feedback loop ensures your plants get water only when they need it — no overwatering, no underwatering.

you can download program for SPIKE3 here

Benefits of Automatic Watering Systems

✅ Water efficiency: Saves up to 50% of water compared to manual watering.
✅ Consistency: Plants get the same care every day.
✅ Convenience: No need to worry when traveling.
✅ Scalability: Works for one pot or an entire garden.

Final Thoughts

By combining soil moisture measurement with SPIKE Prime, you can create a self-sustaining watering system that keeps your plants healthy and thriving — even when life gets busy.

Whether you’re a hobbyist gardener or an agriculture tech enthusiast, soil moisture sensors are your first step toward smarter, more sustainable plant care.