Dahlia tubers should be planted outdoors in Spring, Once the frost has passed, at a depth of 10 cm in fertile, well-drained soil. They thrive in sunny locations and should be spaced about 45 cm apart. In regions with severe cold, it is advisable to lift the dahlias and store them in potting compost during the winter months. To promote growth, a high potash fertilizer should be applied every few weeks throughout the summer, and deadheading should be performed as needed.