Hydroponics is an agricultural cultivation system without using soil media. Hydroponics is an agricultural activity carried out using water as a medium to replace soil. Hydroponics emphasizes meeting the nutritional needs of plants through the flow of water. If nutrients are given through fertilizer in soil media, then in hydroponics, the nutrients are dissolved and flow through water. The concentration of nutrients that dissolve in water will affect the high and low pH of the water. The pH level in the water will affect the development and growth of plants. In addition, air humidity can also affect plant growth, especially for plants grown in a greenhouse. Therefore, special attention is needed to maintain the pH level in the water. The particular concern is when is the right time to replace the water or add nutrients to the water. However, the large land area and the limited number of workers owned by the partners make it difficult for them to monitor the development and growth of existing plants. Therefore, a sensor will be installed in the hydroponic system to monitor the plant's development and growth. Based on the results of the tests and evaluations, the three hydroponic monitoring sensors, which include the pH sensor, nutrient solution concentration sensor, and air humidity sensor, may be properly programmed on the Arduino. The measurements between sensors and manual measurements showed an error value of 0.36% for pH measurements, 0.56% for EC measurements, and 0.42% for humidity measurements.