The present investigation was done during 2021 and 2022 seasons on thirty vines uniform in vigor ‘Superior Seedless’ grapevines, grown under Matay district conditions El-Minia Governorate, Egypt, where the soil texture was loamy clay. The effect of three concentrations of algae extracts (0.25, 0.50 and 0.75 g/L) as well as its frequencies of application (once, twice and thrice) were examined. The obtained data shows that, spraying ‘Superior Seedless’ grapevines with algae extract at different concentrations and frequencies of application play an important and beneficial role in enhancing berries setting %, yield and berries physical and chemical properties. Meanwhile, spraying the vines three times with algae extract at 0.75 g/L present the best results in this concern. However, the most studied characters don’t varied significantly as a result of increasing the concentration (from 0.50 to 0.75 g/L) and the frequencies of application (from two to three times). Then, for improving ‘Superior Seedless’ productivity and berry physical and chemical properties in heavy soils under this experiment or resembling conditions it may be recommended to spraying Superior Seedless grapevines with algae extract at 0.50 g/L two times yearly.