In this study, the effects of seaweed fertilizer treatments in the soil in different growth periods on some quality properties and the development of grafted and non-grafted tomatoes plants grown under greenhouse conditions was investigated. Trial was carried out according to randomized parcels experimental design and as two varieties (grafted, ungrafted), three different growth periods (seedling, flowering and fruit setting stages), three doses of liquid seaweed fertilizer [0, 1. dose (200 ml/100 L water), 2. dose (400 ml/100 L water)], a three replicates. Tomatoes plants were harvested when completed its growth (approximately 120 days) and was determined plant growth and some quality properties. The applied liquid seaweed fertilizer to the soil in different growth periods have supported plant growth and have increased nutrient contents in both two tomatoes varieties. The best growth and nutrient content were obtained in seedling stage applications in the grafted variety. 2. dose fertilizer application to the soil in the seedling stage was increased plant length (177.78 cm), yield (5919 g) and fruit number (105 number). The highest fruit weight were obtained with the ungrafted tomato variety, the applications provided an increase at the 62-83% ratio. Also investigated the quality characteristics has reached similar conclusions, especially 2. dose application in the seedling stage which is the start of the development can be recommended for reaching the best results.