Technological development in the agricultural sector will be able to reduce production costs, especially when fertilizing cultivated land. Watering and fertilizing is one aspect that needs special attention in the agricultural sector. It is important because it can affect plant growth and development. Watering is essential to maintain water availability in the soil and not to disrupt the plant’s metabolic processes. Fertilization must be carried out as needed and at the specified time to increase cultivated plants’ productivity. One technology that can be applied is a system for controlling fertilization automatically. Implementing this automatic fertigation system will make it easier for farmers to fertilize effectively and efficiently. Technological developments have an active role in the efficient use of fertilizer in cultivated plants. This Smart Fertigation System device can help farmers carry out watering and fertilizing cultivated plants. Fertigation itself comes from two words, namely fertilizer and irrigation. This method allows watering and fertilizing to be done simultaneously. Watering and fertilizing carried out simultaneously can be decisive in increasing the growth and productivity of cultivated plants. An important factor that must be considered in the fertilization process is a nutrient solution that is appropriate for the age and type of plant. If the controller detects the volume value is more than the set point, it will automatically turn off the valve and pump motor. From the test results, it was obtained that the output value data was more than the set point of 21.67 mL. This can be caused by the accuracy of the sensor. Delays between controller instructions and actuator responses can also result in differences in watering volume. However, the error value is negligible and tolerable. With a flowmeter sensor, different volumes can be watered according to the age of the plant. It can save more water and fertilizer use compared to using manual cultivation. Watering times can also be done precisely without worrying about forgetting.