Thanks to the precision agriculture technologies developed in recent years, many processes such as irrigation,fertilization, spraying, weeding and harvesting of agricultural products can be done by autonomous systems. Especially in some plant species such as sunflower, when to apply these processes is largely decidedaccording to the developmental stage of the plant. In this study, deep learning methods were used to classifythe developmental stages of sunflower plants. Since the images taken with the drone are high resolution,each of them is divided into 6 equal parts, and then 8 classes are determined and the images belonging toeach class are extracted. A data set consisting of 12800 images in total, 1600 in each class, was created. Sixdifferent deep learning models, namely AlexNet, InceptionV3, ResNet101, DenseNet121, MobileNet andXception, were tested with Sgd, Adam and Rmsprop optimization methods and their performances werecompared. In order to evaluate the success of the models correctly, the trained models were also tested on asecond data set created with images taken from a different terrain and high success rates were obtained. Inaddition, a 7-class test set was created for images that could not be clearly determined at which stage theplant was in, and the success rates of the models were tested. It was observed that the success rate was verylow for the images in the 7-8 intermediate class, and the filters used in the image processing techniques thatwould increase the success rate for this class were applied to the images, and the models were retrained andthe results were evaluated.