Micro climate is very influential factor for plant growth. One of the plant microclimates that greatly affects plants is soil moisture. Soil moisture determines the availability of water in the soil for plant growth. The amount of water needed is also different for each plant. The purpose of this study was to make a prototype of an irrigation system based on soil moisture in mosntrea adansonii. This system uses a soil moisture sensor to read soil moisture and a DHT22 sensor for temperature and humidity data in the plant space. Soil temperature and humidity data will be sent to the smartphone via the Blynk application. The value of soil moisture that will activate the irrigation system in this study is 57%. If the soil moisture value is at 57% then the relay will be active to turn on the pump to irrigate the plants. From observations for 40 days, it was found that the automatic irrigation system worked successfully through the reading of the soil moisture sensor. Monstrea adansonii plants will need water after 10 days from the first day of irrigation. The growth of new shoots was more and the stems grew longer in the plants that were given the intervention. Plant irrigation systems based on soil moisture are able to optimize the amount of water to treat plants with plants growing well. Another benefit obtained is the convenience of the crop irrigation system because it can be done remotely. The use of Internet of Things technology makes it easier for farmers to take care of their plants.