Hi, Lemongrass is a wonderful plant to grow in containers in your region. When cold weather comes, you can move the plants indoors in a sunny windowsill and harvest leaves all winter long. However, it will not prevent mosquitoes from coming into your yard. In fact, no plant will really do this. There is a citronella-scented, scented geranium that is often sold as a mosquito repellent, but unless you stand there and rub the leaves constantly, it will not repel mosquitoes.